ic19 oral abstracts wollongong, australia december 2019...23 12:10-12.30 next generation gold(iii)...
TRANSCRIPT
IC19 Oral Abstracts
Wollongong, Australia
15th-19th December
2019
Monday 16 December 2019
Room 67-107 Page
Chair: Ben Pages
11:00-11:20 First-in-class tumour-selective gadolinium theranostics Louis Rendina (University of Sydney)
10
11:20-11:35 Imaging prostate cancer with monomeric and dimeric inhibitors of membrane antigen labelled with Zr-89 or Ga-68
Asif Noor (University of Melbourne)
11
11:35-11:55 Developing radiometal ligands for PET imaging using multiple approaches Rachel Codd (University of Sydney)
12
11:55-12:10 Insights into biochemical targets and changes induced by Ru(II) arene anticancer complexes Thomas Stewart (University of Sydney)
13
12:10-12.30 Gadolinium-157 and boron-10 enriched agents for neutron capture enhance particle therapy
Ben Fraser (ANSTO)
14
Room 67-104 Page Chair: Shane Telfer
11:00-11:20 Coordination polymers as chiral discriminators in solid state NMR Carol Hua (University of Melbourne)
15
11:20-11:35 Covalent crosslinking of interpenetrated multivariate azido and propargyl-tagged metal- organic frameworks
Mitchell Fishburn (University of Wollongong)
16
11:35-11:55 Encapsulation of metallosupramolecular tetrahedral in halogen bonded networks? John McMurtrie (Queensland University of Technology)
17
11:55-12:10 Spin crossover frameworks containing benzothiadiazole and related heterocycles Hunter Windsor (University of Sydney)
18
12:10-12.30 Metal-organic framework nanocrystals from microemulsions Lyall Hanton (University of Otago)
19
Room 67-102 Page
Chair: Paul Low
11:00-11:20 Multi-photon absorption in metal alkynyl-containing dendrimers and metal alkynylnanoparticle hybrids
Mark Humphrey (Australian National University)
20
11:20-11:35 Low oxidation state group 14 ditetralynes and metal cyclophanes Palak Garg (University of Melbourne)
21
11:35-11:55 Illuminating molecular electronic rectification George Koutsantonis (University of Western Australia)
22
11:55-12:10 Novel organometal hybrid Mn(III) polymer of redox non-innocent Schiff base: study of electrochromic and memrisitive properties
Deepa Oberoi (IIT Roorkee)
23
12:10-12.30 Next generation gold(III) luminophores Koushik Venkatesan (Macquarie University)
24
Room 67-101 Page Chair: Chris Richardson
11:00-11:20 Boron-containing compounds in energy conversion and storage Zhenguo Huang (University of Technology Sydney)
25
11:20-11:35 Tuning the electrochemical properties of layered graphite fluorides by applying chemical and physical pressure
Vittoria Pischedda (UNSW)
26
11:35-11:55 Structural properties and potential applications of supramolecular template chiral mesoporous materials
Alfonso Garcia-Bennet (Macquarie)
27
11:55-12:10 Giving magnetic anisotropy a boost: magneto-structural correlations in a series of 3D mononuclear complexes
Moya Hay (University of Melbourne)
28
12:10-12.30 Good vibrations: dynamics in superionic Cu2Se measured with neutron spectroscopy David Cortie (University of Wollongong)
29
2
Monday 16 December 2019
Room 67-107 Page
Chair: Rachel Codd
15:30-15:50 Speciation of metallodrugs using X-ray absorption spectroscopy Peter Lay (University of Sydney)
31
15:50-16:05 A versatile fluorescent sensing array for platinum and its anti-cancer complexes Linda Mitchell (University of Sydney)
32
16:05-16:25 High-field pulse EPR: a toolbox for studying the chemistry of transition metal cofactors and catalysis
Nick Cox (Australian National University)
33
16:25-16:40 Luminescent iridium(III)-boronic acid complexes for sensing carbohydrates Tahmineh Hashemzadeh (La Trobe)
34
16:40-17.00 Designing arsenic drugs that selectively target leukemia Carolyn Dillon (University of Wollongong)
35
Room 67-104 Page
Chair: Witold Bloch
15:30-15:50 Chiral coordination networks, cages and oddities David Turner (Monash University)
36
15:50-16:05 Covalent post-assembly modification in metallosupramolecular chemistry Derrick Roberts (University of Sydney)
37
16:05-16:25 Discrete metallosupramolecular system: host-guest and magnetism Feng Li (Western Sydney University)
38
16:25-16:40 Construction of photoactive supramolecular coordination cages Michael Pfrunder (University of Queensland)
39
16:40-17.00 Ion mobility mass spectrometry as a probe for molecular self-assembly Nicole Rijs (UNSW)
40
Room 67-102 Page Chair: Erin Leitao
15:30-15:50 Adventures in gold fluorine chemistry Jason Dutton (La Trobe)
41
15:50-16:05 Extending alkali metal mediated magnesiation from nitrogen to phosphorus Michael Stevens (Monash)
42
16:05-16:25 Nucleophilic aluminium: synthesis, structural and reaction chemistry of the aluminyl anion Jamie Hicks (Australian National University)
43
16:25-16:40 Stabilisation and chiral sodium 1-aza allyl amine intermediates for applications in asymmetric synthesis
Jamie Greer (Monash)
44
16:40-17.00 Decorating the room at the bottom – designer nanomaterials for catalytic renewables conversions
Anthony Masters (University of Sydney)
45
Room 67-101 Page Chair: David Cortie
15:30-15:50 Development of potassium-ion batteries Alexey Glushenkov (Australian National University)
46
15:50-16:10 Characterisation of battery materials using X-rays Olga Narygina (Panalytical)
47
16:10-16:30 Calcium carbonate polymorphs – the role of impurity ions Franca Jones (Curtin University)
48
16:30-16:50 Battery electrodes and modulated structures: two worlds collide Siegbert Schmid (University of Sydney)
49
3
Tuesday 17 December 2019
Room 67-107 Page
Chair: Gilles Gasser
11:00-11:20 Targeted delivery of metal complexes for precision oncology Trevor Hambley (University of Sydney)
51
11:20-11:35 Ruthenium(II)-arene thiocarboxylates: identification of a stable dimer cytotoxic to invasive breast cancer cells
Liam Stephens (Monash University)
52
11:35-11:55 Antimicrobial coinage metal N-heterocyclic carbene complexes Peter Barnard (La Trobe)
53
11:55-12:10 Influence of lipophilicity on cellular accumulation and anticancer activity of platinum(IV) prodrugs
Krishant Deo (Western Sydney University)
54
12:10-12.30 Theranostic copper radiopharmaceuticals for neuroendocrine tumours and prostate cancer
Paul Donnelly (University of Melbourne)
55
Room 67-104 Page
Chair: Carol Hua
11:00-11:20 Room temperature spin crossover in ‘hybrid’ coordination polymers Suzanne Neville (UNSW)
56
11:20-11:35 Tunable porous coordination polymers for scavenging waste anaesthetic vapours Keith White (La Trobe University)
57
11:35-11:55 Hydrogen bonded frameworks prepared in water: synthesis, switching behaviour and enzyme encapsulation
Nick White (Australian National University)
58
11:55-12:10 Hydrocarbon adsorption within MOFs containing a contoured aliphatic pore environment Lauren Macreadie (Massey University)
59
12:10-12.30 Lanthanide-based metallosupramolecular materials Jon Kitchen (Massey University)
60
Room 67-102 Page Chair: Jamie Hicks
11:00-11:20 Electron rich PCcarbene iridium complexes for rapid catalytic H/D exchange Warren Piers (University of Calgary)
61
11:20-11:35 Catalysts for CO2 reduction-capture: from mechanistic study to heterogeneous catalysis Biswanath Das (UNSW)
62
11:35-11:55 NHC-iridium complexes for asymmetric hydroamination reactions Reto Dorta (University of Western Australia)
63
11:55-12:10 Developing new synthetic methodology: transition metal catalysis, photocatalysis and dual catalytic strategies
Sinead Keaveney (Macquarie University)
64
12:10-12.30 Synthesis and transition metal-catalysed reactivity of allenyloxazolidinones Chris Hyland (University of Wollongong)
65
Room 67-101 Page Chair: Chris Richardson
11:00-11:20 MLCT and ILCT states in rhenium(I) complexes Keith Gordon (University of Otago)
66
11:20-11:35 Exchange coupling in a Co(II)-radical complex Gemma Gransbury (University of Melbourne)
67
11:35-11:55 Transition metal-organic hydride donor conjugates for electrocatalysis of reduction of carbon dioxide
Stephen Colbran (UNSW)
68
11:55-12:10 Coordination chemistry of the dipyridylpyrrolide ligand James McPherson (UNSW)
69
12:10-12.30 Organic mixed valency across a five charge states of group 13 complexes Louise Berben (University of California Davis)
70
4
Tuesday 17 December 2019
Room 67-107 Page
Chair: Carolyn Dillon
15:30-15:50 X-ray metallomics examines manganese SOD mimeticsHugh Harris (University of Adelaide)
72
15:50-16:05 Towards imaging the pathology of Alzheimers disease with radioactive isotopes of copper Lachlan McInnes (University of Melbourne)
73
16:05-16:25 The transferring cycle: insights into iron metabolism and transport of medicinal and toxic metal ions
Aviva Levina (University of Sydney)
74
16:25-16:40 NMR Studies probing interaction of polynuclear platinum complexes with cell surface glycoamminoglycans
Anil Gorle (Griffith University)
75
16:40-17.00 Visualising biomaterial degradation with luminescent metals Sally Plush (University of South Australia)
76
Room 67-104 Page Chair: Mark MacLachlan
15:30-15:50 Anion binding in mixed ligand M2L4 quadruple helicates David McMorran (University of Otago)
77
15:50-16:05 Diastereoselective control of tetraphenylethene reactivity by metal template self-assembly Aaron Kennedy (UNSW)
78
16:05-16:25 Dectris eiger detectors at the ANSTO MX beamlines – dynamic coordination complexes Jason Price (AS)
79
16:25-16:40 Size-selective hydroformylation by a rhodium catalyst confined in a supramolecular cage Sandra Nurttila (UNSW)
80
16:40-17.00 Supramolecular.org – latest developments: 1:3 binding and a case study on a nickel morpholine photocatalytical complex
Pall Thordarson (UNSW)
81
Room 67-102 Page
Chair: Martyn Coles
15:30-15:50 Polysilanes: the unabridged version Erin Leitao (University of Auckland)
82
15:50-16:05 Developing carborane-supported frustrated Lewis pairs James Watson (UNSW)
83
16:05-16:25 Mixed-valence models of molecules that offer more than more Moore Paul Low (University of Western Australia)
84
16:25-16:40 Sodium magnesiate facilitated cyclisation of imines via C-F activation Samantha Orr (Monash)
85
16:40-17.00 Intramolecular exchange in rhenium alkane complexes: an NMR study Graeme Ball (UNSW)
86
Room 67-101 Page Chair: Franca Jones
15:30-15:50 Cryo atom probe – measuring hydrogen in steels via deuterium charging Julie Cairney (University of Sydney)
87
15:50-16:10 Understanding exchange interactions via organic ligands: an inelastic neutron scattering study of Ni3(OH)2(C4O4)·3H2O
Richard Mole (ANSTO)
88
16:10-16:30 Where the simple things in life seldom are: studies of some AMO4 scheelites Brendan Kennedy (University of Sydney)
89
16:30-16:50 Electromechanical coupling in dipolar molecular compounds Yun Liu (Australian National University)
90
5
Wednesday 18 December 2019
Room 67-107 Page
Don Stranks Awards session Chair: Philip Andrews
11:00-11:15 Exploring the biological activity and photoinduced CO-release of bismuth(III) flavonolate complexes
Kirralee Burke (Monash University)
92
11:15-11:30 Investigations of mixed valency and intervalence charge transfer in metal-organic frameworks
Patrick Doheny (University of Sydney)
93
11:30-11:45 Evaluation of oxorhenium(V) and oxotechnetium(V) complexes for the diagnosis of Alzheimer’s disease
Benjamin Spyrou (University of Melbourne)
94
11:45-12:00 Semiconductivity and spontaneous magnetisation in a mixed-valence iron(III)-chloranilate framework
Martin van Koeverden (University of Melbourne)
95
12:00-12.15 Bis-dithiocarbazate ligands and their non-innocent relationship with copper Jessica Bilyj (University of Queensland)
96
Investigating the chemistry of silver in biological systems Harley Betts (University of Adelaide)
97
Wednesday 18 December 2019
Room 67-107 Page
Chair: Phoebe Glazer
13:30-13:50 The therapeutic versatility of ruthenium(II) complexes Richard Keene (University of Adelaide)
99
13:50-14:05 Investigating the biological interactions of monofunctional platinum complexes Marcus Grazziotto (University of Sydney)
100
14:05-14:25 Semicarbazone and thiosemicarbazone macrocyclic chelators with potential radiopharmaceutical applications
Brett Paterson (Monash University)
101
14:25-14:40 Synthesis and G-quadruplex DNA binding properties of nickel Schiff base complexes Sean Pham (University of Wollongong)
102
14:40-15.00 Interactions of polypyridyl ruthenium complexes with non-canonical and flawed DNA Ben Pages (University of Reading)
103
Room 67-104 Page Chair: Chris Hyland
13:30-13:50 Isolation of molecular catalysts in crystalline frameworks Christian Doonan (University of Adelaide)
104
13:50-14:05 Bodipy-cobalamin complexes for photocatalytic hydrogen production Stephanie Boer (Australian National University)
105
14:05-14:25 The allure of silver: silver(I)amides as catalysts in hydrofunctionalisation reactions Victoria Blair (Monash University)
106
14:25-14:40 Development of tethered dual catalysts: synergy between photo- and transition metal catalysts for enhanced catalysis
Danfeng Wang (Macquarie University) 107
14:40-15.00 Rhodium catalysed dehydropolymerisation of amine-boranes Annie Colebatch (Australian National University)
108
6
Thursday 19 December 2019
Room 67-107 Page
Chair: Sally Plush
11:00-11:20 From antimony to gallium: new metal complexes for combating leishmaniasis Philip Andrews (Monash University)
110
11:20-11:35 Natural product drug discovery – a metal assisted-approach Lukas Roth (University of Sydney)
111
11:35-11:55 Mechanistic insight into steroid hormone biosynthesis: what we learn from comparing species
Lisandra Martin (Monash University)
112
11:55-12:10 Organic and Ir(III) lanthanide conjugates for applications in bio-imaging and sensor developments
Pria Ramkissoon (La Trobe)
113
Room 67-104 Page Chair: Derrick Roberts
11:00-11:20 Untangling the [M2L3]↔[M4L6] equilibrium: using sterics to control cage geometry Jack Clegg (University of Queensland)
114
11:20-11:35 Engineering metal-organic cage materials by solution processing Witold Bloch (University of Adelaide)
115
11:35-11:55 Strategies for assembling both discrete and framework metallo-supramolecular structures – from polyrotaxane generation to pressure induced molecular switching
Len Lindoy (University of Sydney)
116
11:55-12:10 Aromaticity and antiaromaticity in porphyrin nanorings Martin Peeks (UNSW)
117
Room 67-102 Page Chair: Sinead Keaveney
11:00-11:20 Carbon-halogen bond activation by group 9 metal NHC complexes Graham Saunders (University of Waikato)
118
11:20-11:40 Superphenylphosphines: nanographene-based ligands that direct coordination and bulk assembly
Nigel Lucas (University of Otago)
119
11:40-12:00 Polynuclear chemistry of CSe and CTe Anthony Hill (Australian National University)
120
Thursday 19 December 2019
Room 67-107
Chair: Nick Cox
14:05-14:25 Solar powered enzymes to drive the renewable hydrogen economy Trevor Rapson (CSIRO)
122
14:25-14:45 Site-specific incorporation of metal-radionuclides into antibodies for diagnostic imaging Stacy Rudd (University of Melbourne)
123
14:45-15:05 New reactions and new intermediates in cysteine dioxygenase Guy Jameson (University of Melbourne)
124
Room 67-104
Chair: Lauren Macreadie
14:05-14:25 Porous coordination polymers of alkylamine ligands Stuart Batten (Monash University)
125
14:25-14:45 Pressure-induced structural transformation in the metal guanidinium formates Anthony Phillips (QMUL)
126
14:45-15:05 The effect of pressure, guest uptake and structural flexibility on porous materials Stephen Moggach (University of Western Australia)
127
Room 67-102Chair: Jon Kitchen
14:05-14:25 Zapping and smashing light emitting lanthanoid complexes Mark Ogden (Curtin University)
128
14:25-14:45 New examples of lanthanide containing single molecule toroics (SMTs) and of D-F heterometallics
Keith Murray (Monash University)
129
14:45-15:05 Luminescent lanthanide-based complexes and their applications to the detection of biologically and environmentally relevant species
Kelly Tuck (Monash University)
130
7
Oral Session
Abstracts
8
Monday 16th
December
Session 1
9
FIRST-IN-CLASS TUMOUR-SELECTIVE GADOLINIUM THERANOSTICS
Andrew J. Hall1, Amy Robertson1, Eliash M. Hemzal1, F. Eryn Lara1, Nicholas E. Smith1,
Leila R. Hill1, Madleen Busse1, Mingyue Kardashinsky1, Daniel E. Morrison1, Madeline S. A. Windsor1, Zdenka Kuncic2, Hilary Byrne2, Kelly McKelvey3, Ryan J. Middleton4, Naomi A. Wyatt4,
Nicholas R. Howell4, Benjamin H. Fraser 4, Mitra Safavi-Naeini 4 and Louis M. Rendina1*
1School of Chemistry and Sydney Nano, The University of Sydney, NSW, Australia 2School of Physics and Sydney Nano, The University of Sydney, NSW, Australia
3Kolling Institute of Medical Research, The University of Sydney Northern Clinical School, NSW, Australia 4ANSTO, NSW, Australia
Email: [email protected]
R
R‘ E
R”
O
H N O N
N Gd
O
O N O
E = P, As O N
O
OH2
Over the past three decades, brain cancer survival rates in Australia have only barely increased (ca. 1%), a figure
that is twenty times lower than the increase in survival rate for all cancers combined.[1] The most common malignant primary brain tumour is glioblastoma multiforme (GBM), an aggressive, intractable and highly infiltrative tumour. The disease is almost always associated with a poor clinical outcome; almost all patients
succumb to this devastating disease within two years.[1] Accordingly, there is an urgent need to develop new and innovative therapies to treat GBM as all efforts to date have failed spectacularly. We have discovered first- in-class, tumour-selective theranostics based upon the f-block element Gd, the only element that has the potential
to transform three experimental cancer therapies,[2] viz: photon activation therapy (PAT), neutron capture
therapy (NCT), and the newly-described neutron capture enhanced particle therapy (NCEPT).[3] Furthermore, the use of the same Gd platform for diagnostic magnetic resonance imaging (MRI) of GBM greatly expands the utility of our new theranostics.
Gd agents such as Dotarem® have already found extensive non-therapeutic use in medicine to improve MRI
contrast.[4] In recent years, therapeutic application of Gd has been of increasing interest. The selective delivery of Gd to tumour sites and its subsequent accumulation near critical sub-cellular components is a key pre- requisite if Gd agents are to be exploited in cutting-edge cancer therapies. Our Gd theranostics possess a demonstrated capacity to selectively deliver large amounts of this metal ion to the mitochondria of human GBM
cells;[5] tumour cell selectivity is achieved by exploiting the well-established difference in mitochondrial
membrane potential between tumour and healthy cells.[6] To date we have obtained ground-breaking ‘proof-of- principle’ MRI, NCEPT, NCT and PAT data. The key results of this work will be presented.
[1] Australian Institute of Health and Welfare 2017. Cancer in Australia 2017. Cancer series no.101. Cat. no. CAN 100. Canberra: AIHW. Supplementary tables: Ch. 5.
[2] E. L. Crossley, H. Y. V. Ching, J. A. Ioppolo and L. M. Rendina, in Bioinorganic Medicinal Chemistry,
ed. E. Alessio, Wiley-VCH, Weinheim, 2011.
[3] M. Safavi-Naeini, A. Chacon, S. Guatelli, D. R. Franklin, K. B. Bambery and A. B. Rosenfeld, Sci. Rep.,
2018, 8, 16257. [4] J. Wahsner, E. M. Gale, A. Rodríguez-Rodríguez and P. Caravan, Chem. Rev., 2019, 119, 957.
[5] D. E. Morrison, J. B. Aitken, M. D. de Jonge, J. A. Ioppolo, H. H. Harris and L. M. Rendina, Chem.
Commun., 2014, 50, 2252; D. E. Morrison, J. B. Aitken, M. D. de Jonge, J. A. Ioppolo, F. Issa, H. H. Harris
and L. M. Rendina, Chem. Eur. J., 2014, 20, 16602; M. Busse, M. S. A. Windsor, A. Tefay, E.
Kardashinsky, J. M. Fenton, D. E. Morrison, H. H. Harris and L. M. Rendina, J. Inorg. Biochem., 2017,
177, 313.
[6] T. J. Lampidis, S. D. Bernal, I. C. Summerhayes and L. B. Chen, Cancer Res., 1983, 43, 716.
10
IMAGING PROSTATE CANCER WITH MONOMERIC AND DIMERIC INHIBITORS OF PROSTATE SPECIFIC
MEMBRANE ANTIGEN LABELLED WITH ZIRCONIUM-89 OR GALLIUM-68
Asif Noor,1 Jessica K. Van Zuylekom,2 Stacey E. Rudd,1 Kelly Waldeck,2 Peter D. Roselt,2
Mohammad B. Haskali,2 Michael Wheatcroft,3 Eddie Yan,3 Rodney J. Hicks,2,4 Carleen Cullinane,2,4
and Paul S. Donnelly*1
1School of Chemistry and Bio21 Molecular Science and Biotechnology Institute University of Melbourne, Parkville, Victoria 3010, Australia.
2Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia 3Telix Pharmaceuticals Limited, Suite 401, 55 Flemington Road, North Melbourne, VIC 3051, Australia.
4Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia Email: [email protected]
Positron emission tomography (PET) is a diagnostic tool for cancer imaging which utilizes positron emitting
radionuclides such as 68Ga and 89Zr. The aim of the research presented is to make a single ligand platform
suitable for imaging prostate cancer with either 68Ga which has a short half-life of only 68 min or 89Zr which
has a long half-life of 78 hours. Desferrioxamine-B (H3DFO) is a bacterial siderophore and is commonly used
chelator for 89Zr but it also shows affinity to radioisotopes of gallium. A more efficient squaramide derivative
of desferrioxamine-B (H3DFOSq) was used and attached to a glutamate-ureido-lysine based inhibitor of the
prostate-specific membrane antigen (PSMA) which is an enzyme that is over expressed in prostate cancer.1,2
The H3DFOSq and glutamate-ureido-lysine moieties were systemically modified to adjust the pharmacokinetics and tumour targeting properties of the final bifunctional constructs. The new mono-/dimeric PSMA targeting
molecules were radiolabelled with 89Zr and 68Ga to give radiotracers that produce high quality PET images in LNCaP xenograft tumour bearing mice. Modification of the linker molecule led to the molecules with superior binding to PSMA positive cells and the tumour targeting was improved by preparing dimeric ligands containing
two PSMA targeting glutamate-ureido-lysine units coupled to one H3DFOsq chelator. The new dimeric ligands
can be used for imaging PSMA positive tumour with either 68Ga or 89Zr radionuclides.
Figure 1. Chemical structure and whole-body micro-PET and CT images of mice bearing LNCaP xenograft tumours after post injection of [89ZrL4] and [68GaL4] tracers.
References,
1. S. E. Rudd, P. Roselt, C. Cullinane, R. J. Hicks, P. S. Donnelly, Chem. Commun. 2016, 52, 11889.
2. M. Eder, M. Schafer,U. Bauder-Wust, W. E. Hull, C. Wangler, W. Mier, U. Haberkorn, M. Eisenhut. .
Bioconjugate Chem. 2012, 23, 688.
11
DEVELOPING RADIOMETAL LIGANDS FOR POSITRON EMISSION TOMOGRAPHY IMAGING USING MULTIPLE
APPROACHES
Rachel Codd1*, Christopher J. M. Brown1, Tomas Richardson-Sanchez1, James L. Wood1, A. Sresutharsan1, Michael P. Gotsbacher1, and William Tieu1,2
1The University of Sydney, School of Medical Sciences, Camperdown, NSW 2006, Australia 2South Australian Health and Medical Research Institute, Molecular Imaging & Therapy Research Unit, North
Terrace, SA 5000, Australia Email: [email protected]
Expansions in The Radiometal Periodic Table call for the production and evaluation of chelates with properties well matched to a given radiometal. Recent work in our group has focused on the design of chelates that coordinate Zr(IV) to support the clinical development of the radiometal Zr-89 for use in positron emission tomography (PET) imaging. Foundational theoretical studies have established that Zr(IV) has a coordination
number preference > 6,1 which has led to the design of high-dentate ligands containing hard base donor atoms.
The hexadentate hydroxamic acid desferrioxamine B (DFOB) has been modified by others2,3 to improve
selectivity towards Zr(IV) above its natural metal ion target Fe(III). Our group has developed methods to access linear and macrocyclic tetrameric hydroxamic acid ligands tailored towards Zr(IV). We have used innovations
in microbiology, macrocycle assembly and improved synthetic protocols.4–7 Our methods development aims to provide access to structurally diverse ligands that allow us to build knowledge of the relationships between structure and properties, including metal ion selectivity, affinity, and solubility.
[1] J. P. Holland, N. Vasdev, Dalton Trans. 2014, 43, 9872.
[2] M. Patra, A. Bauman, C. Mari, C. A. Fischer, O. Blacque, D. Haussinger, G. Gasser, T. L. Mindt,
Chem. Commun. 2014, 50, 11523.
[3] S. E. Rudd, P. Roselt, C. Cullinane, R. J. Hicks, P. S. Donnelly, Chem. Commun. 2016, 52, 11889.
[4] W. Tieu, T. Lifa, A. Katsifis, R. Codd, Inorg. Chem. 2017, 56, 3719.
[5] T. Richardson-Sanchez, W. Tieu, M. P. Gotsbacher, T. J. Telfer, R. Codd, Org. Biomol. Chem. 2017,
15, 5719. [6] A. Sresutharsan, W. Tieu, T. Richardson-Sanchez, C. Z. Soe, R. Codd, J. Inorg. Biochem. 2017, 177,
344.
[7] C. J. M. Brown, M. P. Gotsbacher, J. P. Holland, R. Codd, Inorg. Chem. 2019,
https://doi.org/10.1021/acs.inorgchem.9b00878.
12
RuQI
INSIGHTS INTO BIOCHEMICAL TARGETS AND CHANGES INDUCED BY RU(II) ARENE ANTICANCER
COMPLEXES
Thomas J. Stewart1*, Aviva Levina,1 Nicholas P. Farrell2 and Peter A. Lay1
1School of Chemistry, University of Sydney, NSW, Australia 2Department of Chemistry, Virginia Commonwealth University, VA, USA
Email: [email protected]
0.0006 1094 cm-1
(nucleic acid)
0.0004
0.0002
966 cm-1
(nucleic acid)
0.0000
-0.0002
-0.0004
Control
1123 cm-1 oxaloRAPTA-C
-0.0006
(nucleic acid) UNICAM-1
iodoRAED-C
RAS-1H
-0.0008
1415 cm-1
(protein)
1080 cm-1 RAPTA-C
(nucleic acid) RuQCl
RAS-1T
1450 1400 1350 1300 1250 1200 1150 1100 1050 1000 950 900
Wavenumber / cm-1
Figure 1: The 1450 – 900 cm-1 region of the second-derivative infrared spectrum of microvesicles derived from
MDA-MB-231 cells treated with nine Ru complexes, showing considerable differences in biochemical profiles.
Ruthenium complexes have emerged as promising alternatives to existing platinum drugs as cancer
chemotherapeutics, with Ru(II) arene complexes being particularly attractive owing to the number of properties
and antitumour effects they can possess depending on ligand choice.[1] However in the case of Ru(II) arene complexes, these effects, along with mechanisms of action and biological targets, are not fully understood.
Extracellular vesicles (EVs) are membrane-enclosed particles excreted by all known cell types. Understanding of key roles they play in a number of biological processes including intercellular communication, disease
progression and drug action mechanisms is currently emerging.[2] They offer unique, multifaceted opportunities
to study both cancer as a disease, and Ru(II) arene complexes as potential treatments. Additionally, the role of interactions between proteoglycan species and metal-based drugs remains an underdeveloped, yet highly
exploitable, research direction in chemotherapy.[3]
In this project, a library of Ru(II) arene complexes covering a variety of ligands and modes of antitumour
activities has been prepared, and investigated in breast cancer cell lines and their secreted EVs through
spectroscopic techniques and biochemical assays. Distinct differences in the biochemical profiles of EVs
sourced from cells treated with the complexes were observed, with implications for impacts on cell signalling,
drug resistance and the development of disease mechanisms. Our recent metalloglycomics studies on the
interactions of the complexes with proteoglycans will also be discussed.
References
[1] A. Renfrew, Chimia 2009, 63, 217.
[2] P. Vader, E. A. Mol, G. Pasterkamp, R. M. Schiffelers. Adv. Drug Deliv. Rev. 2016, 106, 148. [3] N. P. Farrell, A. K. Gorle, E. J. Peterson, S. J. Berners-Price, in Metallo-Drugs: Development and Action of
Anticancer Agents (Eds. A. Sigel, H. Sigel, E. Freisinger, R. K. O. Sigel) 2018, Vol. 18, Ch. 4, pp 109–140 (De
Gruyter: Berlin/Boston).
Seco
nd
derivative
absorb
an
ce
/ a
. u.
13
GADOLINIUM-157 AND BORON-10 ENRICHED AGENTS FOR NEUTRON CAPTURE ENHANCED PARTICLE
THERAPY
Benjamin H. Fraser1*, Nicholas R. Howell1, Amy Robertson2, Naomi A. Wyatt1, Daniel E. Robertson2, Nicholas Smith2, Mitchell A. Klenner1, Ryan J. Middleton1, Louis M. Rendina2, Mitra
Safavi-Naeini1
1ANSTO, NSW, Australia
2School of Chemistry and Sydney Nano, The University of Sydney, NSW, Australia
Email: [email protected]
Neutron Capture Enhanced Particle Therapy (NCEPT)[1]
is a radical new approach to particle therapy treatment for cancer patients. NCEPT works by capturing the thermal neutrons (generated at the primary target volume) with gadolinium-157 or boron-10 enriched agents. This process has significant potential to boost radiation dose to the primary tumour, reduce adverse side effects, and kill radio-resistant cells on the primary tumour margins and beyond. Some of the most promising targets for NCEPT include paediatric brain tumours due to the conservative, or sometimes non-existent, treatment plans for paediatric patients with external beam radiotherapy. To date we have synthesised, characterised and evaluated several gadolinium-157 and boron-10 agents for “proof of principle” in vitro experiments with human glioblastoma cells. These agents
include [10
B]boronophenylalanine ([10
B]BPA) - which is currently used in humans for boron neutron capture
therapy[2]
- and [Gd157
]DOTA-TPP (Figure 1).[3]
Critical to producing large quantities of gadolinium-157 agents for in vitro and future in vivo experiments has been optimisation of preparative HPLC buffer conditions. These conditions afforded the ligand in a chemical form ready for use in large scale, high yielding syntheses of gadolinium-157 compounds. Initial in vitro results showed that incubation of glioblastoma cells
with either [157
Gd]DOTA-TPP or [10
B]BPA, and subsequent particle irradiation (helium or carbon ions), increases overall radiation sensitivity via the NCEPT effect. The observed effect is a 3-5 factor increase in radiation dose to the primary target volume, but importantly, we also observe an NCEPT effect for cancer cells outside of the primary target volume. These results have encouraged follow up in vivo studies which will be reported on in the near future. This has also spurred on-going development of a new generation of agents for NCEPT treatment of other cancer classes.
[1] M. Safavi-Naeini, A. Chacon, S. Guatelli, D. R. Franklin, K. B. Bambery, A. B. Rosenfeld. Sci Rep, 2018,
1:16257.
[2] E. L. Crossley, H. Y. V. Ching, J. A. Ioppolo and L. M. Rendina, in Bioinorganic Medicinal Chemistry,
ed. E. Alessio, Wiley-VCH, Weinheim, 2011.
[3] D. E. Morrison, J. B. Aitken, M. D. de Jonge, J. A. Ioppolo, H. H. Harris and L. M. Rendina, Chem.
Commun., 2014, 50, 2252; D. E. Morrison, J. B. Aitken, M. D. de Jonge, J. A. Ioppolo, F. Issa, H. H. Harris
and L. M. Rendina, Chem. Eur. J., 2014, 20, 16602;
14
COORDINATION POLYMERS AS CHIRAL DISCRIMINATORS IN SOLID STATE NMR
Carol Hua1*, Aditya Rawal,2 and Hui Min Tay1
1The University of Melbourne, Parkville, Victoria, 3010, Australia 2Mark Wainwright Analytical Centre, The University of New South Wales, 2052, Australia
Email: [email protected]
Chirality is an integral part of life with the key role chiral recognition plays in biological and physiological processes. The chirality of drug molecules is particularly important as each enantiomer may interact with
metabolic and regulatory processes in vastly different ways.1 This is vividly illustrated by the drug thalidomide which was administered to pregnant women to alleviate morning sickness and nausea in the 1950s. The development of new methods for determining the chiral purity of molecules is therefore of great importance to
not only the pharmaceutical industry, but also in agrochemicals and food additives2 with 56% of drugs currently
in use consisting of chiral molecules.3
Coordination polymers (CPs) are crystalline materials comprising of inorganic nodes bridged by multidentate
ligands to form extended structures including 1D chains, 2D sheets or 3D frameworks. The high porosity and
tunable three-dimensional structure of CPs allows for the systematic modification of pore chemistry and size.
This enables tailored chiral environments to be designed, making such materials potentially well-suited to act
as chiral selectors as they can encapsulate guest molecules in a manner similar to natural enzymes. This
presentation will detail our efforts to synthesise chiral CPs through the incorporation of amino-acid derived
ligands as well as their application as chiral discriminators as elucidated through x-ray crystallographic and
solid state NMR studies. The use of 113Cd as a highly sensitive probe in the presence of varied intermolecular
interactions and the framework dynamics of CPs determined through solid state NMR studies will be discussed.
References
1. M. Eichelbaum, A. S. Gross, in Advances in Drug Research, Vol. 28 (Eds.: B. Testa, U. A. Meyer), Academic
Press, 1996, pp. 1-64.
2. T. J. Ward, K. D. Ward, Anal. Chem., 2012, 84, 626-635.
3. L. A. Nguyen, H. He, C. Pham-Huy, Int. J. Biomed. Sci., 2006, 2, 85-100.
15
COVALENT CROSSLINKING OF MULTIVARIATE INTERPENETRATED AZIDO- AND PROPARGYL- TAGGED
METAL-ORGANIC FRAMEWORKS
M. Fishburn1*, C. Richardson1 and P. Wagner2
1School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia
2ARC Centre of Excellence for Electromaterials Science and the Intelligent Polymer Research Institute,
Australian Institute for Innovative Materials, University of Wollongong, Wollongong, NSW 2522, Australia
Email: [email protected]
Metal-organic Frameworks (MOFs) are porous materials with high functional group density within their solvent accessible pores. Post-synthetic Modification (PSM) is the predominant method of tethering new or
otherwise difficult-to-access functionality to the MOF backbone.1
Crosslinking of frameworks in
interpenetrated MOFs has been shown to improve the thermal and solvent tolerance of MOFs.2
In this presentation, I will explore my research into the covalent crosslinking of an interpenetrated MOF via PSM. The aim of this study was to develop post-synthetic chemistry to covalently crosslink adjacent linkers
within IRMOF-9 frameworks. The “click” chemistry of azides and alkynes is widely utilised for PSM.3
In a study by Sada, a bis-azide functionalised MOF was reacted with a tetra-alkyne reagent to crosslink across the
pores and generate a polymer template.4 In this study, a multivariate MOF containing a mixture of azide and
alkyne functionalities was crosslinked under copper catalysed and thermally promoted conditions and the results were compared.
1. Z. Wang, S. M. Cohen. Chem Soc Rev. 2009, 38, 1315.
2. Y.-H. Kiang, G. B. Gardner, S. Lee, Z. Xu. J Am Chem Soc. 2000, 122, 6871-83.
3. Y. Goto, H. Sato, S. Shinkai, K. Sada. J Am Chem Soc. 2008, 130, 14354-5.
4. T. Ishiwata, Y. Furukawa, K. Sugikawa, K. Kokado, K. Sada. J Am Chem Soc. 2013, 135, 5427-32.
16
ENCAPSULATION OF METALLOSUPRAMOLECULAR TETRAHEDRA IN HALOGEN BONDED NETWORKS?
Marco Pandullo1, Aidan J. Brock1, Michael C. Pfrunder1, Aaron S. Micallef1, Jack K. Clegg2, Kathleen M. Mullen1 and John C. McMurtrie1*
1 Queensland University of Technology (QUT), QLD, Australia 2 University of Queensland, QLD, Australia
Email: [email protected]
Mononuclear transition metal complexes readily co-crystallise with perfluoroiodobenzenes to form crystals in which the metal complexes are encapsulated in anionic halogen bonded networks. These networks comprise the
halide counteranions and perfluoroiodofluorobenzenes.1,2 This can be exploited to manipulate the crystal
packing arrangement of metal complexes that can in turn cause significant changes to the physical properties of the metal complexes and their crystals (e.g. modulation of spin crossover profile and/or manipulation of excited state lifetimes and photoluminescence quantum yields). Co-crystals of this type are almost always, large, well- formed and strongly diffracting allowing relatively easy structural characterisation.
Large metallosupramolecular entities are almost always difficult to crystallise. Even when crystals are obtained
they are often highly unstable to loss of solvate - complicating characterisation and limiting opportunities for
applications. These limitations may be overcome by encapsulation of the metallosupramolecular species in
crystalline halogen bonded networks. This would also facilitate the modulation of their electronic properties
(SCO and photoluminescence) in a similar way to that already demonstrated for mononuclear species. This
presentation will focus on the synthesis of some new tetranuclear metallosupramolecular tetrahedra (example
pictured) and our progress towards encapsulating them in halogen bonded networks.
1. M. C. Pfrunder, A. S. Micallef, L. Rintoul, D. P. Arnold, J. C. McMurtrie. Cryst. Growth Des. 2016, 16, 681.
2. M. C. Pfrunder, A. J. Brock, A. S. Micallef, J. K. Clegg, J. C. McMurtrie. Cryst. Growth Des. 2019, 19, 5374.
17
SPIN CROSSOVER FRAMEWORKS CONTAINING BENZOTHIADIAZOLE AND RELATED HETEROCYCLES
Hunter J. Windsor1*, Deanna M. D’Alessandro1 and Cameron J. Kepert1* 1School of Chemistry, The University of Sydney, NSW, Australia
Email: [email protected]
Figure 1 Spin crossover of [Fe(L)(Au(CN)2)2]·MeCN, showing a reversible one-step spin transition, with the
transition temperatures 200 and 230 K on cooling and heating, respectively.
Spin crossover (SCO) Fe(II) complexes are a class of compounds that can be reversibly controlled to exist in
either their low or high spin electronic states.1 Applying different external stimuli such as temperature, pressure,
light irradiation, or guest modulation, allows these materials to exhibit a wide range of switching behaviours
manifested through changes in their magnetic state, colour, or structure.1 The transition between the two spin states therefore provides a route towards engineered functional devices that can act as, for example, responsive
thermal, light, or pressure modulated chemical and magnetic switches.2 In rarer instances, multi-step transitions
can occur where a complex can exist in multiple fractional electronic states,3 with the order of the transition
typically being highly dependent on solvent molecules present in the material. We present the first SCO material exhibiting 1- to 4-step transitions depending on the included guest molecules, and the first known example of a SCO material constructed from a chalcogenadiazole ligand. Additionally, we have explored the effect of single heteroatom substitution on the incorporated chalcogenadiazole ligand and tracked the resulting change in SCO behaviours through variable temperature magnetic susceptibility measurements. This work highlights the remarkable host–guest sensitivity of a SCO framework with different guest molecules and provides a platform
for additional applications that extend towards ternary, quarternary, and even quinary-based molecular sensors.4
References
1. O. Sato, J. Tao, Y. Z. Zhang. Angew. Chem. Int. Ed. 2007, 46, 2152-2187.
2. J.-F. Létard, P. Guionneau, L. Goux-Capes. Top. Curr. Chem. 2004, 235, 221-249.
3. M. J. Murphy, K. A. Zenere, F. Ragon, P. D. Southon, C. J. Kepert, S. M. Neville. J. Am. Chem. Soc. 2017,
139, 1330-1335.
4. E. Milin, V. Patinec, S. Triki, E. E. Bendeif, S. Pillet, M. Marchivie, G. Chastanet, K. Boukheddaden. Inorg
Chem. 2016, 55, 11652-11661.
18
METAL-ORGANIC FRAMEWORK NANOCRYSTALS FROM MICROEMULSIONS
Lyall R. Hanton*1, Alice M. T. Craig1,Natalie R. Lagesse1,2, Jonathan L. Falconer1,2, Aaron C. Y.
Tay1,2, , Carla J. Meledandri1,2 and Shane G. Telfer2,3
1Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand 2The MacDiarmid Institute for Advanced Materials and Nanotechnology
3Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand Email: [email protected]
Illustration of the preparation of MOFs at the nanoscale using a microemulsion approach,
Metal organic frameworks (MOFs) represent a promising class of highly porous materials which have
demonstrated exceptional potential for industrial and technological applications such as gas storage, sensing,
and catalysis. On the macroscopic scale, however, slow mass transfer rates of guest molecules can inhibit the
application of MOFs for these (and other) applications. Furthermore, in their as-synthesised form as porous
powders, MOFs have limited processability, which can also impede their practical use.
As a result, recent work in our group has focused on fabricating nanostructured forms of metal-organic
frameworks (nMOFs) by using microemulsion-based synthetic methods. Using a colloidal approach has
provided valuable insight into the nucleation and growth of these nanocrystals and enabled understanding of
how various synthetic parameters affect the physicochemical properties of the resulting nMOFs. This has
afforded the ability to concurrently control the composition, size, morphology, crystallinity and porosity of
nMOFs, which influences their gas adsorption behaviour. Additionally, the ability to tune the surface chemistry
of the crystals through the microemulsion-based synthesis has enabled their solvent dispersibility, and
subsequent incorporation into a secondary matrix to form hybrid materials, thereby improving their
processability.
In this presentation, the versatile fabrication method used to access nMOFs will be discussed. A selection of
interesting dispersible nanocrystalline MOFs prepared in our group will be presented, along with a discussion
of their unique physical and chemical properties.
19
MULTI-PHOTON ABSORPTION IN METAL ALKYNYL-CONTAINING DENDRIMERS AND METAL ALKYNYL- NANOPARTICLE HYBRIDS
Mark G. Humphrey,*,1 Cristóbal Quintana,1 Linda Zhang,1 Mahbod Morshedi,1 Marie P. Cifuentes1
1 Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
Email: [email protected]
We have been studying the nonlinear optical (NLO) properties of metal alkynyl complexes, in studies ranging from small complexes to dendrimers. While our early focus was on molecular quadratic and cubic NLO coefficients, materials with multi-photon absorption (MPA) properties have become of increasing interest for applications such as microfabrication, bioimaging, photodynamic therapy, and frequency upconversion lasing. We have recently been exploring the MPA behaviour of rod-like, star, and dendritic OPVs and
oligo(phenylenethynylene)s (OPEs) bearing bis(diphosphine)ruthenium moieties,1 and have very recently
extended our research to include metal alkynyl-nanoparticle hybrids;2 the results of these studies and our ongoing research will be presented.
1. P. V. Simpson, L. A. Watson, A. Barlow, G. Wang, M. P. Cifuentes, M. G. Humphrey, Angew. Chem. Int. Ed. 2016, 55,
2387.
2. C. Quintana, M. Morshedi, H. Wang, J. Du, M. P. Cifuentes, M. G. Humphrey, Nano Lett., 2019, 19, 756-760.
20
Low Oxidation State Group 14 metal Heavier Ditetrelynes and Metallo Cyclophanes
Palak Garg1 and Prof. Cameron Jones2* 1,2Monash University, VIC, Australia
Email: [email protected]
Figure. Multiply bonded digermynes 1 and 2; Metallo cyclophanes 3, 4 and 5.
The last two decades have seen a search of main-group metal complexes as a cheaper and the less toxic alternative catalyst of the transition metal complexes. These complexes can be kinetically stabilised by using sterically demanding bulky ligands which prevent the disproportionation and the oligomerisation of these complexes. [1] In this context, in past bulky amide [RNR’] and amidiante [RC{NR’}2]
- ligand has been extensively exploited for the stabilisation of low oxidation state group 14 element (Ge, Sn, Pb) complexes as their electronic and steric environment can be easily modified by varying the substituent on the nitrogen atom. [1] These complexes show catalytic activity in hydroboration, hydrosilylation and hydrogenation of alkenes and alkynes. [2] Herein, we report the multiply bonded amido-substituted digermynes [CyLGeGeCyL], which have been synthesised from bulky monomeric amido-germenium(II) chloride LGeCl precursors (L = N(SiCy3)(Ar*), N(SiCy3)(Ar†); Ar* = C6H2Me{C-(H)Ph2}2-4,2,6), Ar† = C6H2Me{C-(H)Ph2}2-4,2,6). In addition, the first 1,4- and 1,3-phenyl bridged based bidentate amide and amidinate Metallo cyclophanes [{μ2-p-(iPr3SiN)2C6H4}M]2
(M= Ge, Sn) and [{μ2-m-(Ar†NC(tBu)NC6H4NC(tBu)NAr†}Ge]2 were successfully isolated in high yield, respectively. X-ray crystallography structural studies and solution-state NMR studies will be presented.
References [1] J. Li, C. Schenk, C. Goedecke, G. Frenking, C. Jones. J. Am. Chem. Soc. 2011, 133, 18622.[2] T.J. Hadlington, M. Driess, C. Jones, C. Chem. Soc. Rev. 2018, 47, 4176.
Ar SiR3''
iPr iPr iPr iPr
N
Ge
iPr
N R3''Si Ar
Ar= Ar*, R''= Cy; CyL*GeGeCyL* 1
Ar= Ar , R''= Cy; CyL GeGeCyL 2
iPr
Si
N
M
N
Si iPr iPr
Si iPr
N
M
N
Si iPr iPr iPr
Ar
tBu
N Ge
N N
tBu
N Ar
Ge
Ge
N Ar
N N N
tBu tBu Ar
M = Ge 3, Sn 4 5
21
ILLUMINATING MOLECULAR ELECTRONIC RECTIFICATION
Max Roemer,a Mark C. Walkey,1 Angus Gillespie,1 David Jago,1 Sven Kampmann,1 David Costa- Milan,2 Inco J. Planje,3 Hong Zhang,4 Jehan Alqahtani,4 Sara Sangtarash,4 Hatef Sadeghi,4
Alexandre N. Sobolev,1 Brian W. Skelton,1 Arnaud Grosjean,1 Christian A. Nihuis,3 Colin Lambert,4
Simon J. Higgins,2 Richard J Nicols,2 Matthew J. Piggott,1 George A. Koutsantonis1,*
1School of Molecular Sciences, University of Western Australia. 2Department of Chemistry, University of Liverpool
3Department of Chemistry, National university of Singapore -4Department of Physics, Lancaster University
Email: [email protected]
spiropyran
N O
merocyanine
SP MC
dihydropyrene cyclophanediene
DHP CPD
The semiconductor industry has acknowledged that it will abandon the pursuit of Moore’s law,1 ie. the doubling
of electronic chip component density per year. Efforts to maintain pace with Moore’s Law2 have driven decades
of technological achievement and new materials science in the semiconductor industry.3 However, despite
IBM’s demonstration of 5 nm transistors, and Samsung’s 10 nm FinFET technology, the International Roadmap
for Devices and Systems predicts the end of CMOS technology by 2024.4 Furthermore, top-down scaling is
becoming breathtakingly complex, and increasingly giving way to more complex and challenging 3-D designs
using extreme ultraviolet (EUV) lithography (e.g. IBM’s GAAFET Samsung’s 3nm FinFET5). The use of
molecules is seen as a way overcoming the challenges of top-down nanofabrication. Molecular electronics has
the potential of alleviating the challenges confronting the conventional solid-state semiconductor.
We consider alternative switching elements, and hence current rectification, based on dihydropyrene (DHP),
and spiropyran, (SP) as precursors to switchable molecular electronics components in this work.
This talk describes the synthesis and properties of SP and DHP based molecular switches, some containing
metals. We have synthesised new 2,7-bisalkyne DHPs with internal alkyl groups (methyl, ethyl, butyl) by
multistep syntheses starting from 5-triisopropylsilyl acetylene-dimethylisophthalate. Our synthetic approaches
to new SP molecules will also be discussed. Preliminary molecular conductance results will also be presented.
Here we demonstrate that the conductance of both DHP and SP molecules can be measured using STM-BJ
method, providing some surprising results. Additionally, the conductance, and indeed rectification, of current
has been demonstrated in SAM based large area ensembles measured by the EGaIn methods.
References
1. Waldrop, M. M. Nature 2016, 530, 144-147.
2. Mack, C. A. IEEE Trans. Semiconduct. Manuf. 2011, 24, 202-207.
3. Thompson, S. E.; Parthasarathy, S. Mater. Today. 2006, 9, 20-25.
4. International Roadmap for Devices and Systems, https://irds.ieee.org/roadmap-2017, 2017.
5. EE Times, https://www.eetimes.com/document.asp?doc_id=1333318# 2018.
R
R
R
R
N O
22
NOVEL ORGANIC METALLIC HYBRID MN(III)-POLYMER OF REDOX NON-INNOCENT TRIDENTATE SCHIFF’S
BASE ORGANIC LIGAND: STUDY OF ELECTROCHROMIC AND NON-VOLATILE MEMRISTIVE PROPERTIES
Deepa Oberoi1* and Anasuya Bandyopadhyay1
1Department of Polymer & Process Engineering, IIT Roorkee- Saharanpur campus, India Email: [email protected]
The present investigation is a continuation of our initiative to synthesize simple and efficient hybrid polymers
for studying their applications in electrochromism1,2 and non-volatile memristive devices3.. Herein, we probe
the multifunctional properties of Mn(III) polymer of redox non-innocent Schiff’s base ligand. Literature shows
that study of terpyridines and PVDF, PMMA based polymers have been exploited mainly for this purpose, and
examples electrochromic and memristive study of Schiff’s base hybrid polymers4 are scarce in the literature.
Therefore, in the present report, we have investigated these Schiff's base hybrid polymers, synthesized through
a very simple and cost-efficient route. This adopted design and synthesis strategy for this polymer will open a
path for the new domain of the group of materials with efficient multifunctional properties. The complete
synthesis of the polymer and its elemental characterizations by FTIR, 1H NMR has been presented in this work.
UV-titration experiments have established for determination of 1:1 organic ligand and metal ion complexation.
Furthermore, the growth of the polymer has been monitored by AFM, and FESEM techniques. Mn(III)-hybrid
polymer have been found to be redox active and showed reversible electrochromism upon applied potential
switching between 0 V to -1.4 V. Upon application of this small amount of potential causes the initial red colour
of the polymer to switch to bleached state with the corresponding change in the UV absorption spectrum of
solution of polymer. The i-V characterization of this device shows resistive bistable memory behavior with
charge retention up to 10,000 seconds and good repeatability has been exhibited by write-read-erase-read
(WRER) cycles test. Therefore, we have been successful in establishing and exploring this new field other than
terpyridines and PVDF like polymers for multifunctional properties.
Graphical Abstract
[1] C. W. Hu, T. Sato, J. Zhang, S. Moriyama and M. Higuchi, J. Mater. Chem. C, 2013, 1, 3408–3413.
[2] A. Bandyopadhyay, S. Sahu and M. Higuchi, J. Am. Chem. Soc., 2011, 133, 1168–1171.
[3] L. O. Chua and S. M. Kang, Proc. IEEE, 1976, 64, 209–223.
[4] D. Oberoi, P. Dagar, U. Shankar, G. Vyas, A. Kumar, S. Sahu and A. Bandyopadhyay, New J. Chem., 2018, 42, 19090–19100
23
1
d*
T1 N
N Au
S1
T1N
Au
excita
tio
n
em
issio
n
no
n-r
ad
iative d
eca
y
no
n-r
ad
iative d
eca
y
NEXT GENERATION GOLD(III) LUMINOPHORES
Robert Malmberg1, Tobias von Arx1,2, Olivier Blacque2 and Koushik Venkatesan1* 1 Department of Molecular Sciences, Macquarie University, North Ryde, NSW, Australia
2 Department of Chemistry, University of Zurich, Zurich, Switzerland. Email: [email protected]
d*
S
R R
R R
S0
Gold(III) complexes
S0
Gold(III) complexes with strong -donor
Figure: Modified Jablonski diagram
Transition metal complexes have been intensively investigated for applications in phosphorescent OLEDs
(PhOLEDs) due to their interesting luminescent properties.[1] N-Heterocyclic Carbene (NHC) bearing
platinum(II) and iridium(III) cyclometalated complexes have been previously synthesized and their luminescent
properties have been investigated.[2,3] In stark contrast to these investigations, NHC cyclometalated gold(III)
complexes has been only rarely explored. Different synthetic strategies have been effectively pursued to develop
novel classes of Au(III) complexes with significantly varied ligand environment giving rise to complexes with
exceptional thermal stability and phosphorescence properties.[4,5] The judicious choice of the ligands allows a
facile way to tune the emission properties to wavelengths and their efficiencies previously not possible. The
highly emissive nature of the compounds coupled with their stability could make NHC cyclometalated gold(III)
complexes as suitable candidates for applications in PhOLEDs as the next generation triplet phosphors.
[1] H. Yersin, W. J. Finkenzeller, Highly Efficient OLEDs with Phosphorescent Materials, (Ed: H. Yersin),
Wiley-VCH, Weinheim, 2007.
[2] T. Fleetham, G. Li, L. Wen, J. Li, Adv. Mater., 2014, 26, 7116.
[3] H.-F. Chen, T. Batagoda, C. Coburn, P. I. Djurovich, M. E. Thompson, S. R. Forrest, Nat. Mater., 2015, 15,
92.
[4] T. von Arx, A. Szentkuti, T. N. Zehnder, O. Blacque, K. Venkatesan, J. Mater. Chem. C., 2017, 15, 3765.
[5] R. Malmberg, T. von Arx, O. Blacque, K. Venkatesan, To be Submitted, 2019.
excita
tio
n
em
issio
n
no
n-r
ad
iative d
eca
y
no
n-r
ad
iative d
eca
y
24
BORON-CONTAINING COMPOUNDS IN ENERGY CONVERSION AND STORAGE
Zhenguo Huang1
1School of Civil & Environmental Engineering, University of Technology Sydney, NSW, Australia Email: [email protected]
Boron, hydrogen, and nitrogen form many compounds together (denoted as BHN) that have high hydrogen
capacity (weight percent). These compounds typically feature extensive intra- and/or intermolecular N−Hδ+---
Hδ-−B dihydrogen interactions, which enable facile dehydrogenation.1 We have been developing novel synthesis
methods and exploring new BHN compounds for hydrogen storage, which has been one of the bottlenecks for
wide deployment of hydrogen fuel cell cars. Boron is also a key element of the electrolyte salt for the emerging
Na-ion and Mg batteries. Its ability to form large and electrochemically stable ions enables good tuning of the
interactions between anions and cations, and the conductivity and electrochemical windows of the
corresponding electrolytes. For example, sodium-difluoro(oxalato)borate (NaDFOB) outperforms the most
widely used commercial salts for Na-ion batteries in terms of rate capability and cycling performance.2 This
breakthrough in hydrogen storage and Na-ion batteries has been successfully commercialized in partnership
with Boron Molecular, a specialist chemical manufacturer. Boron and nitrogen together form a layered
compound, hexagonal boron nitride (h-BN), which is isostructural to graphene. By guiding the dehydrogenation,
BHN compounds can be made to form few-atomic-layered h-BN.3 We have been able to grow large few-atomic-
layer h-BN nanosheets on Cu substrates. h-BN nanosheets could be an excellent atomically thin protective layer
over Cu substrate if it is made with high quality.4 Our recent findings have seen boron nitride nanosheets
dramatically improve the thermal response of temperature-sensitive hydrogels.5 h-BN nanosheets have recently
been found to show interesting catalytic properties such as selective oxidative dehydrogenation of alkane to
alkene. The impressive recent advances in the synthesis and understanding of the properties of the boron-based
materials provides a powerful toolkit for the further exploration of boron as a key element in the field of energy
research.6
References
1. Z. Huang, T. Autrey, Energy & Environ. Sci., 2012, 5, 9257.
2. J. Chen, Z. Huang, C. Wang, S. Porter, B. Wang, W. Lie, H. Liu, Chem. Comm., 2015, 51, 9809.
3. M. H. Khan, H. Liu, X. Sun, Y. Yamauchi, Y. Bando, D. Golberg, Z. Huang, Mat. Today, 2017, 20, 611. 4. M. H. Khan, S. S. Jamali, A. Lyalin, P. J. Molino, L. Jiang, H. K. Liu, T. Taketsugu, Z. Huang, Adv.
Mater., 2017, 29, 1603937.
5. F. Xiao, S. Naficy, G. Casillas, M. H. Khan, T. Katkus, L. Jiang, H. Liu, H. Li, Z. Huang, Adv. Mater.,
2015, 27, 7196.
6. Z. Huang, S. Wang, R.D. Dewhurst, N. V. Ignat’ev, M. Finze, H. Braunschweig, Angew. Chem. Int. Ed,
2019, accepted.
25
Tuning the electrochemical properties of layered graphite fluorides by applying chemical and physical pressure
V. Pischedda1,2*, L. Djuandhi1, J. Wo1, C. Cavallari3, S. Radescu4, M. Dubois5, N. Batisse5 and N. Sharma1
1School of Chemistry, UNSW, NSW, Australia
2Institut Lumière Matière, UMR-CNRS5306, Université Lyon1, Villeurbanne, France
3ESRF- The European Synchrotron Radiation Facility, Grenoble, France
4 Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Tenerife, Spain
5 ICCF, Université Clermont Auvergne, UMR-CNRS6296, Aubière, France
Email: [email protected]
a) b) c) d)
Figure: Crystal structures of graphite fluorides for different fluorination percentages:
a) 25%; b) and c) 50%; d) 100%. From1
Layered graphitic materials are extremely important as they are used as electrodes in primary Li batteries2. In
particular, fluorinated graphites (FG), CyFx, are regarded as the most promising compounds to achieve the
highest theoretical specific capacity of Li/CF batteries3. Furthemore, the high reversible capacity of Na/CFx
battery, recently reported4, made them promising cathode materials for future rechargeable sodium batteries.
FGs exhibit various types of C-F bonds (covalent, semi-covalent or semi-ionic bonds), tunable F/C ratios, and different structures controlled by direct fluorination and exfoliation methods. The type and amount of C-F bonds control properties such as bandgap opening, surface chemical activity, hydrophobic/hydrophilic
character, mechanical properties and thermal conductivity5.
Our recent theoretical and experimental studies, have shown, that by varying internal chemical pressure, C hybridization and the band structure of (C2F)n can be modified resulting in valence and conduction bands touching at the K point like in graphene, thus turning the wide band gap fluorinated graphite into a semi-
metal4. Furthermore, the application of external static pressure of few GPa provokes an irreversible stacking-
sequence-change phase transformation providing a new pathway to further improve their electrochemical properties and maximize the energy and power density.
At UNSW, we are testing the electrochemical potentials of these fluorinated graphites with different C-F bonding and fluorination rate (i.e. x in CFx) for secondary sodium ion batteries uses focusing on the understanding of the mechanism involved during discharge-charge cycles. Preliminary results will be presented.
1
C. Cavallari et al. Carbon, 2019, 147, 1. 2 M. Fukuda, T. Iijima. In Collins, D.H., Ed. Power Sources 5. Academic Press:New York, 1975, p.713.
3 W. Liu et al. ACS Appl. Mater. Interfaces, 2014, 6, 2209.
4 F. Withers, S. Russo, M. Dubois and M. F. Craciun. Nanoscale Research Letters. 2011, 6, 526.
5 V. Pischedda, S. Radescu, M. Dubois et al. Carbon, 2017, 6, 690.
26
(a) (b)
(c) (d)
Structural properties and potential applications of supramolecular templated chiral
mesoporous materials.
Alfonso Garcia-Bennett,1,* Yanan Huang1
1Molecular Sciences, ARC Center for Nanoscale Biophotonics, Macquarie University, Sydney,
Australia
Over the last decade we have developed the synthesis of a range of supramolecular template
mesoporous materials based on the use of folic acid and guanosine monophosphate as pore
templates, NFM-1 and NGM-1 respectively.1, 2 These materials show some unique properties in
comparison to other hexagonal 2d-mesostructures such as MCM-41. The self-assembly of NGM-
1 and NFM-1 are synthesized relies on Hoogsteen-type hydrogen bonding to form tetramers,
subsequent π-stacking interactions between adjacent tetramers promote the formation of columnar
phases.3 The structure of the supramolecular template is imprinted on to the surface of the resulting
mesopores. This can be ascertained from X-ray diffraction (XRD), transmission electron
microscopy and circular dichroism
studies.
In this report we will present the
synthesis mechanism and how the
material characteristic features can be
controlled. Additionally, we will
present a series of carbon replica
materials prepared using the
supramolecular template as carbon
source as well as their properties.
Our recent work shows that these
materials have potential applications
for the detection of biomolecules,4 in
drug delivery,5 in chiral separation
and as potential enantiomeric
catalyst supports. These application
areas will be reviewed.
Figure 1: (a) Representative scheme of supramolecular assembly within the mesopores
of NGM-1 showing the guanosine template. (b) Scanning Electron Microscopy image of
NFM-1 chiral particles. (c) XRD patterns of changes to supramolecular stacking of as-
synthesized NGM-1 as a function of guanosine concentration. (d) Raman spectra of
carbon replica of NFM-1 showing the presence of graphitic sp3 carbon.
1. R. Atluri, N. Hedin and A. E. Garcia-Bennett, J Am Chem Soc, 2009, 131, 3189-3191. 2. C. J. Bueno-Alejo, L. A. Villaescusa and A. E. Garcia-Bennett, Angew Chem Int Ed Engl, 2014, 53, 12106-12110. 3. R. Atluri, M. N. Iqbal, Z. Bacsik, N. Hedin, L. A. Villaescusa and A. E. Garcia-Bennett, Langmuir, 2013, 29, 12003-12012. 4. T. L. Church, D. Bernin, A. E. Garcia-Bennett and N. Hedin, Langmuir, 2018, 34, 2274-2281. 5. C. Zhou and A. E. Garcia-Bennett, Journal of Nanoscience and Nanotechnology, 2010, 10, 7398-7401.
27
GIVING MAGNETIC ANISOTROPY A BOOST: MAGNETO-STRUCTURAL CORRELATIONS IN A SERIES OF 3D
MONONUCLEAR COMPLEXES
Moya A. Hay1§, Mark Murrie1*
1School of Chemistry, University of Glasgow, Glasgow, UK. §Current address: School of Chemistry, University of Melbourne, Melbourne, Australia.
Email: [email protected]
Single-molecule magnets, which show magnetic memory from a purely molecular origin with an associated
thermal energy barrier, show great promise for applications such as high density data storage.1 To improve their economic viability in modern technologies, significant research has focused on increasing the height of the energy barrier to magnetic relaxation. Maximising the magnetic anisotropy of these systems, which arises
through spin-orbit coupling effects, is one way this could be achieved.2 Mononuclear 3d transition metal systems
are good candidates to study magneto-structural correlations which govern magnetic anisotropy, with their
coordination environment easily perturbed and tuned to induce dramatic observable effects.3 Of particular interest for achieving large magnetic anisotropies and a barrier to spin reversal in 3d complexes are those with
trigonal bipyramidal (TBP) geometry.5,6 Herein we report a series of TBP 3d complexes adhering to a strict
axial D3h symmetry leading to the enhancement of the magnetic anisotropy and resulting in slow relaxation of
magnetisation. Several methods have been used to investigate the enhanced magnetic anisotropy (HF-EPR, FDMR, CTM, ab initio) with the results guiding the design and study of future molecular magnetic materials.
1 Y.-S. Ding, K.-X. Yu, D. Reta, F. Ortu, R. E. P. Winpenny, Y.-Z. Zheng and N. F. Chilton, Nat.
Commun., 2018, 9, 3134.
2 F.-S. Guo, B. M. Day, Y.-C. Chen, M.-L. Tong, A. Mansikkamäki and R. A. Layfield, Science (80-. ).,
2018, 362, 1400–1403.
3 S. Gómez-Coca, D. Aravena, R. Morales and E. Ruiz, Coord. Chem. Rev., 2015, 289–290, 379–392.
4 P. C. Bunting, M. Atanasov, E. Damgaard-Møller, M. Perfetti, I. Crassee, M. Orlita, J. Overgaard, J.
van Slageren, F. Neese and J. R. Long, Science (80-. )., 2018, 362, eaat7319.
5 G. A. Craig, A. Sarkar, C. H. Woodall, M. A. Hay, K. E. R. Marriott, K. V Kamenev, S. A. Moggach,
E. K. Brechin, S. Parsons, G. Rajaraman and M. Murrie, Chem. Sci., 2018, 9, 1551–1559. 6 M. A. Hay, A. Sarkar, G. A. Craig, L. Bhaskaran, J. Nehrkorn, M. Ozerov, K. E. R. Marriott, C.
Wilson, G. Rajaraman, S. Hill and M. Murrie, Chem. Sci., 2019, 10, 6354–6361.
28
GOOD VIBRATIONS: DYNAMICS IN SUPERIONIC CU2SE MEASURED WITH NEUTRON SPECTROSCOPY
D. L. Cortie1*, N. Islam1, D. Yu2, R. Mole2, X. L. Wang2
1Institute for Superconducting and Electronic Materials, University of Wollongong, NSW, Australia 2The Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
Email: [email protected]
In recent years, a new generation of superionic thermoelectric materials has gained popularity.1 These materials,
such as Cu2Se, offer superb performance for harvesting waste-heat and this is enhanced by their low thermal
conductivity. The central mechanism for the low thermal conductivity, however, is still under intense debate.
Here we present neutron spectroscopy measurements on Cu2Se which reveal the unique atomic motions present
in the time-disordered crystal structure. In tandem with the experiments, molecular dynamics calculations were
performed based on density functional theory. A numerical method based on Fourier transforms was deployed
to enable direct comparison of the molecular dynamics together with the neutron spectroscopy data. Excellent
agreement between the theoretical and experimental vibrational density-of-states is demonstrated.2 Animations
of the molecular dynamics highlight that the instantaneous crystal structure deviates from the average symmetry
owing to low-energy vibrational modes of distortion. The spectral analysis shows that terahertz acoustic modes
survive into the superionic state, where they coexist with long-range copper diffusion. The different time-scales
of the two types of motions ensure that they are not strongly coupled. Finally, by analysing the free-energy
surfaces, we show that a critical factor for the low thermal conductivity is the anharmonic character of the
chemical Cu-Se bonding interactions.
[1] H. Liu et al. Nature Materials 2012, 11, 422. [2] M. Li, D.L. Cortie et al. Nanoenergy 2018, 53, 993.
29
Monday 16th
December
Session 2
30
SPECIATION OF METALLODRUGS USING X-RAY ABSORPTION SPECTROSCOPY
Peter A. Lay,1* Aviva Levina1
1. School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia Email: [email protected]
Most metal containing drugs are pro-drugs in which the metal-containing active species differ from the
administered drug. Therefore, in order to understand the efficacy and potential toxicity of metal containing
drugs, it is necessary to establish analytical methods that can provide speciation information in all media to
which the drugs are exposed; from the point of administration to the target cells or organ. It is also important
to understand metal speciation in diseases. X-ray absorption spectroscopy (XAS) is an ideal tool that enables
element-specific speciation with a relatively high sensitivity in biological samples.
The application of XAS speciation to the biotransformation of metal-containing drugs will be discussed with
references to the reactions that occur in the gastrointestinal tract (for orally administered drugs), the blood and
in cells. In addition, since much of the research in lead drug design involves in-vitro studies with cell culture
media, the reactions that occur in this media also have to be considered.
The advantages and disadvantages of various XAS approaches to speciation will be discussed with reference to
anti-diabetic drugs and supplements (Cr, Mo, and V) and anti-cancer drugs (Ga, Rh, Ru and V) [1,2]. These
will include the combination of native protein gels with microprobe X-ray techniques [3]; microprobe X-ray
techniques for single cells and tissues [4]; 3D speciation approaches for bulk cells and tissues; [5] and linear
least-squares regressions; and multi-modal imaging (vibrational and X-ray microprobes) [6].
REFERENCES
1. A. Levina, P A. Lay Chem. Asian J., 2017, 12, 1692-1699.
2. A. Levina, D. C. Crans, P. A., Lay Coord. Chem. Rev. 2017, 352, 473-498. 3. L. Finney Y. Chishti T. Khare, C. Giometti, A. Levina, P. A. Lay, S. Vogt, ACS Chem. Biol., 2010, 5,
577-587.
4. L. E. Wu, A. Levina H. H. Harris Z. Cai B. Lai, S. Vogt, D. E. James, P. A, Lay, Angew. Chem., Int.
Ed., 2016, 55, 1742–1745.
5. A. Levina, A. I. McLeod, P A. Lay Chem. Eur. J., 2014, 20, 12056-12060. 6. M. J. Hackett, J. B. Aitken, F. El-Assad, J. A., McQuillan, E. A. Carter, H. J. Ball, M. J. Tobin, D.
Paterson, M. D. de Jonge, R. Siegele, D. D. Cohen S. Vogt, G. E. Grau, N. H. Hunt P. A. Lay, Sci. Adv. 2015,
1, e1500911.
31
A VERSATILE FLUORESCENT SENSING ARRAY FOR PLATINUM AND ITS ANTI-CANCER COMPLEXES
Linda Mitchell1, Clara Shen1 and Elizabeth J. New1
1School of Chemistry, University of Sydney, NSW, Australia Email: [email protected]
Fig. 1 The fluorescent array technique
Platinum-based drugs are currently one of the most widely-used classes of cancer chemotherapeutics. Whilst
effective at treating cancer, the side-effects accompanying platinum-based chemotherapy are severe and create
challenges during treatment.1 In particular, major side-effects such as nephrotoxicity, myelosuppression and
neurotoxicity are often severe enough to necessitate dose-reduction, reducing their efficacy. Directly
monitoring platinum levels in patients during treatment, rather than monitoring the resulting toxicity, could
enable more effective modification of dosages and overall treatment plans. The ability to detect and monitor
platinum complexes in fluids via a facile and readily available technique will therefore be highly beneficial.
There are a large number of small molecule fluorescent sensors that exist to study heavy metals in biology.2
Whilst these types of probes are very sensitive, complex mixtures such as plasma and other biological fluids
contain a variety of other interfering analytes. It therefore becomes a great challenge to create a sensor that
selectively responds to a chosen analyte without interference from competing species.
A fluorescent array (Fig. 1) is a technique that has the potential to overcome this difficulty.3 In such studies,
we are not aiming to use a single, highly selective probe, but to gain specificity by having a number of cross-
reactive probes, which we run in an array, and then subject to statistical analysis (PCA and LDA). Using these
methods, we have developed the first fluorescent array for selective detection of platinum complexes in serum
and monitoring of platinum levels in patients following chemotherapy.
(1) S. Dilruba, and G. V. Kalayda, Cancer Chemother. Pharmacol. 2016, 77, 1103–1124.
(2) D. J. Hare, E. J. New, M. D. De Jonge, and G. McColl, Chem. Soc. Rev. 2015, 44, 5941–5958.
(3) Y. Geng, W. J. Peveler, and V. M. Rotello, Angew. Chemie - Int. Ed. 2019, 5190–5200.
32
HIGH-FIELD PULSE EPR: A TOOLBOX FOR STUDYING THE CHEMISTRY OF TRANSITION METAL
COFACTORS AND CATALYSIS
Nick Cox Research School of Chemistry, Australian National University, Acton ACT, Australia
Email: [email protected]
High-field Pulse Electron Paramagnetic Resonance (EPR) has recently emerged as a powerful technique in the
study of biological systems.1 It represents a sensitive, non-invasive, site-selective spectroscopy for the analysis
of both molecular and macroscopic properties. With the support of the Australian Research Council and the
Max Planck Institute for Chemical Energy Conversion in Mulheim (Germany), we are establishing Australia’s
first high-field (3 T, W-band) pulse EPR facility in Canberra as part of a cross-university EPR platform
involving ANU, USyd, UNSW, UoW and UQ. This facility is designed to serve EPR spectroscopists across
Australia and will be unique in the Asia-Pacific region. Performing EPR at higher magnetic fields enhances
sensitivity, due to the increased spin polarization and spectral resolution, as seen in nuclear magnetic resonance.1
The high-field regime also extends the range of systems amenable for study, such as high spin or integer-spin
systems which are often considered EPR silent and allows implementation of new cutting-edge
multidimensional pulse EPR methods.2
Heterobimetallic Mn/Fe complexes represent a new class of biological cofactors. They are found in the R2
subunit of class Ic ribonucleotide reductases (R2c) and R2-like ligand-binding oxidases (R2lox).3 Although the
protein-derived metal ligands are the same in both groups of proteins, the connectivity of the two metal ions
and the chemistry each cofactor performs are different: in R2c, a one-electron oxidant, the Mn/Fe dimer is linked
by two oxygen bridges (μ-oxo/μ-hydroxo), whereas in R2lox, a two-electron oxidant, it is linked by a single
oxygen bridge (μ-hydroxo) and a fatty acid ligand. EPR spectroscopy rationalizes this inherent chemical flexibly
is in terms of tuning of the local site geometry and electronic state of the Mn ion.4 Coupled with mutagenesis it
identifies a second coordination sphere residue which directs the divergent reactivity of the protein scaffold.5
Mechanisms via which heterometicallic metal loading is favored over homometallic loading are also briefly
discussed.6
1. Cox N, Nalepa A, Pandelia ME, Lubitz W, Savitsky A. Methods in Enzymology 2015 563, 211-249
2. Cox N, Retegan M, Neese F, Pantazis DA, Boussac A, Lubitz W. Science 2014, 345, 804-808
3. Griese JJ et al. Proc. Natl. Acad. Sci. U.S.A 2013 110:17189-17194
4. Shafaat HSS et al. J. Am. Chem. Soc. 2014 136:13399–13409
5. Kutin Y et al. J. Biol. Chem. 2019 pp.jbc-RA119.
6. Kutin Y et al. J. Inorg. Biol. Chem. 2016 162:164-177
33
LUMINESCENT IRIDIUM(III)-BORONIC ACID COMPLEXES FOR SENSING CARBOHYDRATES
Conor F. Hogan, Peter J. Barnard and Tahmineh Hashemzadeh* Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Victoria,
3086, Australia Email: [email protected]
The synthesis and photophysical properties of a family of cyclometalated iridium(III) complexes Ir(ppy)2(L) where (ppy=2-phenyl-pyridine) and (L= pyridyl-1,2,4-triazole ligand or pyridyl-1,2,4-oxidazole ligand substituted with a boronic acid group) are reported. Luminescence molecules functionalised with boronic acid
groups have shown great potential for sensing and imaging carbohydrates and the capacity of these Ir(III)
complexes described here to bind to sugars has been evaluated.1 Mass spectrometric studies show promising binding of these complexes to the simple sugar fructose. The complexes showed emission at λmax=590, and quasi-reversible oxidation and a reversible reduction. In addition, the electrochemiluminescence (ECL) properties of one of these complexes has also been investigated and the results showed the same emission spectra as that observed in the photoluminescence studies.
References
1. Swanick, K. N.; Ladouceur, S.; Zysman-Colman, E.; Ding, Z., Bright electrochemiluminescence of
iridium (III) complexes. Chem.Commun. 2012, 48 (26), 3179-3181.
34
DESIGNING ARSENIC DRUGS THAT SELECTIVELY TARGET LEUKEMIA
Carolyn T. Dillon1,2*, Judith A. Carrall1,2, Jacob M. Lambert1,2, Katja de Roo1,2, Hugh H. Harris3
and Barry Lai4
1School of Chemistry and Molecular Bioscience, University of Wollongong, NSW, Australia 2Molecular Horizons Institute, University of Wollongong, NSW, Australia
3Department of Chemistry, University of Adelaide, SA, Australia 4X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Illinois, USA
Email: [email protected]
Arsenic trioxide (ATO), marketed in Australia as Phenasen®, is administered for the treatment of acute
promyelocytic leukemia (APL).1,2 If left untreated, this disease can cause death within three months; however,
ATO treatment can result in the cure of approximately 80% of patients.1,2 In recognition of the dual therapeutic and toxic properties of arsenic, significant attention has focussed on the design and development of arsenic complexes that selectively target leukemia cells.
Leukemia homing peptides have been coordinated to arsenic derivatives to produce complexes that target
leukemia cells to reduce their potential adverse side effects.3 Work has focussed on optimising the stability of
this class of complexes, as monitored by X-ray absorption spectroscopy. Graphite furnace atomic absorption
spectroscopy has shown that the complexes, do indeed, target leukemia cells but are excluded from healthy
blood cells, while MTT assays indicate that these effects translate to selective toxicity towards the leukemia
cells. A number of other in vitro biological assays have been performed to determine the mechanism(s) of
action of these complexes including microprobe synchrotron radiation X-ray fluorescence imaging and tubulin
polymerisation assays. The results of these investigations will be presented.
References
1. J.-X.. Liu, G.-B. Zhou, S.-J. Chen, Z. Chen. Curr. Opin. Chem. Biol. 2012, 16, 92.
2. M. T. Rojewski, S. Korper, H. Schrezenmeier. Leuk. Lymphoma 2004, 45, 2387.
3. P. Laakkonen, M.E. Akerman, H. Biliran, M. Yang, R. Ferrer, T. Karpanen, R. M. Hoffman, E.
Ruoslahti. PNAS 2005, 101, 9381.
35
CHIRAL COORDINATION NETWORKS, CAGES AND ODDITIES
David R. Turner
School of Chemistry, Monash University, Clayton, VIC 3800, Australia
Email: [email protected]
The prevalence of chirality in natural systems means that the synthesis, purification and detection of chiral
molecules are important areas of research. To achieve these goals it is important that materials are developed
that have a high degree of selectivity towards the desired substrates.
Recent work in our group has focused on the design and synthesis of chiral coordination compounds, both
discrete cage-like species and porous coordination polymers. Studies involving several families of diimide
ligands, containing amino acid terminal groups, give insights to the geometric and steric influences on the
structure and activity of the resulting complexes.
The structures of coordination polymers containing naphthalene- or perylene-diimide ligands are highly dependent on the amino acid that is used. A robust metallomacrocyclic synthon has been identified and its applications, and limitations, from both crystal engineering and supramolecular perspectives have been
explored.1 A subset of these materials separate racemic analytes in a liquid-chromatographic application.2
The use of copper-acetate paddlewheels as structural components has led to discrete helical cages. Handedness can be controlled by the ligands used and can be templated in systems containing achiral analogues. A growing
family of lantern-type M4L4 species allow alteration of the size and nature of the cage, and far larger octahedral
M12L12 cages show enantioselective guest sorption.3 Various other metallosupramolecular species can also be
accessed, including discrete catenanes and M8L8 ‘squares’.4 More recently, fluorescent core groups have been
incorporated with changes in solid-state emission brought about by structural changes in the presence of guest species.
1. (a) L.J. McCormick, D.R. Turner. CrystEngComm 2013, 15, 8234; (b) S.A. Boer, C.S. Hawes, D.R. Turner.
Chem. Commun. 2014, 50, 1125; (c) N. Kyratzis, W. Cao, E.I. Izgorodina, D.R. Turner. CrystEngComm,
2018, 20, 4115.
2. S.A. Boer, Y. Nolvachai, C. Kulsing, C.S. Hawes, P.J. Marriott, D.R. Turner. Chem. Eur. J. 2014, 20,
11308.
3. (a) S.A. Boer, D.R. Turner. Chem. Commun. 2015, 51, 17375; (b) S.A. Boer, K.F. White, B. Slater, A.J.
Emerson, G.P. Knowles, W.A. Donald, A.W. Thornton, B.P. Ladewig, T.D.M. Bell, M.R. Hill, A.L.
Chaffee, B.R. Abrahams, D.R. Turner. Chem. Eur. J. 2019, 8489.
4. (a) S.A. Boer, R.P. Cox, M.J. Beards, H. Wang, W.A. Donald, T.D.M. Bell, D.R. Turner. Chem. Commun.
2019, 55, 663; (b) S.A. Boer, D.R. Turner. Chem. Asian J. 2019, 2853.
36
COVALENT POST-ASSEMBLY MODIFICATION IN METALLOSUPRAMOLECULAR CHEMISTRY
Derrick A. Roberts1*, Ben S. Pilgrim
1 and Jonathan R. Nitschke
3
1School of Chemistry and Sydney Nano Institute, The University of Sydney, NSW 2006
2School of Chemistry, The University of Nottingham, NG7 2RD, UK
3Department of Chemistry, The University of Cambridge, CB2 1EW, UK
Email: [email protected]
The field of metallosupramolecular chemistry has witnessed a recent surge in the use of covalent post-assembly
modification (PAM) reactions to directly alter self-assembled structures.1
Early examples of PAM focused on the late-stage introduction of functional groups to avoid chemical incompatibilities that might occur between
building blocks during self-assembly, and to provide access to structures inaccessible through self-assembly alone (e.g., molecular knots). However, recent work has drastically extended the scope of PAM, venturing beyond its traditional role as a late-stage derivatization method. This presentation summarises our contributions
to these new developments, including the use of covalent reactions to ‘lock-down’ dynamic supramolecules,2
triggering controlled supramolecular structural transformations using covalent stimuli,3
and achieving signal
transduction through a covalent PAM cascade sequence.4 We hope that our work highlights the emerging utility
of covalent PAM strategies for expanding the synthetic toolbox available to supramolecular chemists.
References
1. D.A. Roberts, B. S. Pilgrim, J. R. Nitschke. Chem. Soc. Rev., 2018, 47, 626.
2. D.A. Roberts, A. M. Castilla, T. K. Ronson, J. R. Nitschke, J. Am. Chem. Soc. 2014, 136, 8201.
3. D.A. Roberts, B. S. Pilgrim, J. D. Cooper, T. K. Ronson, S. Zarra, J. R. Nitschke, J. Am. Chem.
Soc. 2015, 137, 10068.
4. B. S. Pilgrim, D. A. Roberts, T. G. Lohr, T. K. Ronson, J. R. Nitschke, Nat. Chem. 2017, 9, 1276.
37
DISCRETE METALLO-SUPRAMOLECULAR SYSTEM: HOST-GUEST AND MAGNETISM
Feng Li*
School of Science, Western Sydney University, Penrith NSW 2751, Australia
Email: [email protected]
In the realm of supramolecular chemistry, finite nano-scale metallo-supramolecular ensembles with interesting
and beautiful molecular structures have received very considerable attention over recent years.1-3 The resulting metallo-architectures range from simple molecular ellipses, through higher polygons and large polyhedrons, to
a small number of intricately interwoven structures that bridge the boundaries between Art and Science. These ensembles, which typically form on the nanometer scale, display both considerable beauty and applications,
particularly between host-guest and magnetism.4,5 A condition for the rational strategies of such metal organic structures is that the metal ion(s), organic component(s), solvent(s) and anion(s) display the required steric and
electronic complementarity to promote formation of the molecular architecture of interest.4,5
1. L. Li, D. J. Fanna, N. D. Shepherd, L. F. Lindoy and F. Li, J. Incl. Phenom. Macrocycl. Chem.,
2015, 3-12
2. F. Li and L.F. Lindoy, Aust. J. Chem. 2019, 72, 731-741
3. F. Li, J. K. Clegg, R. B. Macquart, G. V. Meehan and L. F. Lindoy, Nature Commun., 2011, 2: 205.
4. A. R. Craze, M. M. Bhadbhade, C. J. Kepert, L. F. Lindoy, C. E. Marjo, F. Li, Crystals, 2018, 8,
376
5. A. R. Craze, M. M. Bhadbhade, Y. Komatsumaru, C. E. Marjo, S. Hayami and F. Li, Inorg. Chem.
Under review
38
CONSTRUCTION OF PHOTOACTIVE SUPRAMOLECULAR COORDINATION CAGES
Michael Pfrunder1,2*, Gina Quach1, Jonathon E. Beves3 and Evan G. Moore1
1School of Chemistry & Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia 2Current address: School of Chemistry, Physics and Mechanical Engineering, Queensland University of
Technology, Brisbane, QLD, Australia 3School of Chemistry, University of New South Wales, Sydney, NSW, Australia
Email: [email protected]
Figure 1 (above) Construction of different supramolecular assemblies using functionalised metalloligands
(blue) with preorganised C2, C3 or C4 symmetric linkers, resulting in edge-capped (a) or face-capped tetrahedra
(b), and edge-capped (c) or face-capped cubes (b).
Figure 2 (right) X-ray crystal structure of coordination cage that emulates the structure
from Figure 1a, containing Ru(2,2′-bipyridine)3 subunits at the vertices (inert
metalloligand) and a Cd(2,2′:6′,2″-terpyridine)2 subunit along each edge (labile C2
symmetric linker).
The construction of metallosupramolecular coordination cages has traditionally relied on rigid organic ligands
and kinetically labile coordination chemistry involving metals such as Fe, Cu, Zn, and Co to drive formation of
a thermodynamically favoured product.1 However, the nature of this approach is somewhat restrictive on the
incorporation of kinetically inert metal ions which often have important physical and chemical properties. For
this reason, the construction of cages incorporating photoactive components derived from inert metals such as
Ru(II) and Ir(III) remains a significant scientific challenge. Instead, the use of functionalised metalloligands (as
shown in Fig. 1) can facilitate the preparation of a variety of supramolecular assemblies that incorporate
kinetically inert metals, including edge-capped and/or face-capped tetrahedra and/or cubes.2,3 Our most recent
results will be presented using this approach for the construction of supramolecular cages incorporating
photoactive Ru(II) and Ir(III) complexes, which may have a variety of applications including catalysts for
organic photoredox reactions.
1. A. J. Brock, H. Al-Fayaad, M. C. Pfrunder, J. K. Clegg. Functional metallo-supramolecular
polyhedral capsules and cages, 2017, United Kingdom: RSC Books, 325.
2. M. B. Duriska, S. M. Neville, B. Moubaraki, J. D. Cashion, G. J. Halder, K. W. Chapman, C. Balde, J.
F. Létard, K. S. Murray, C. J. Kepert, S. R. Batten. Angew. Chemie Int. Ed., 2009, 48, 2549.
3. L. Li, D. J. Fanna, N. D. Shepherd, L. F. Lindoy, F. Li. J. Incl. Phenom. Macrocycl. Chem., 2015, 82,
3.
Metalloligand containing kinetically
inert metal ion
39
ION MOBILITY MASS SPECTROMETRY AS A PROBE FOR MOLECULAR SELF-ASSEMBLY
Nicole J. Rijs1* 1UNSW Sydney, Sydney, NSW, Australia
Email: [email protected]
“[In regards to supramolecular complexes] …mass spectrometry goes far beyond the analytical characterisation
of the complexes with respect to their exact masses, elemental compositions, isotope patterns, charge states,
and their stoichiometries or the analysis of impurities.” [1]
Understanding the intrinsic properties of molecules, molecular building blocks and aggregates is key to realizing
the bottom-up design of functional molecules and materials, and especially catalysts. The Rijs group explores
such molecular units in isolation, for example, via the pristine gas phase environment of specially modified
mass spectrometers, and by carefully controlled sampling of dynamic structures from solution using highly
reproducible ion-sources. The end goal of this research is the rational design of efficient catalyst and enzyme-
like molecules.
Electrospray ionization-mass spectrometry (ESI-MS) is an effective technique for characterising reaction
intermediates in synthetic and catalytic transformations. Additionally, ion-mobility spectrometry (IMS) has
emerged as a very powerful technique for monitoring self-assembly because IMS is ideal for examining the size
and shape of non-covalent complexes. It offers the advantage of isomer separation on the millisecond timescale,
and measurement of the assembly’s topology, and as such, enables the study of conformational dynamics within
that time frame. Together ESI-MS and IMS represent two complementary analytical methods of monitoring
self-assembling molecules on a millisecond timescale.
In this presentation, recent examples revealing the structural complexity of metallo complexes of (i) bis-β-
diketonates and (ii) cyclotricatechylenes in solution will be highlighted. In order to systematically investigate
their structures, complexes were formed by dissolving synthesised ligand and appropriate salt and introduced
to the gas phase via nanoESI or ESI. Travelling wave ion mobility, along with other mass spectrometry
approaches, were used to examine the structure of the resulting cationic and anionic complexes. The measured
collisional cross sections of the complexes are thus compared with computed cross sections and reveal the role
of the various bonding effects for the first time.
1. B. Baytekin, H. T. Baytekina C.A. Schalley Org. Biomol. Chem., 2006,4, 2825-2841
40
ADVENTURES IN GOLD FLUORINE CHEMISTRY
Jason L. Dutton1* 1Department of Chemistry and Physics, La Trobe University, Melbourne, Victoria
Email: [email protected]
N
F Au F
N
The chemistry of organometallic and coordination compounds containing an Au-F bond is underdeveloped, with only about a dozen examples comprehensively characterized to date. In most compounds the Au-F bond
is highly reactive (and therefore interesting!),1 but this high reactivity renders systematic investigation of the bond difficult. We have discovered a cationic bis Au(III)-F complex supported by pyridine ligands featuring
the shortest Au-F bond yet recorded.2 The complexes are also far more stable than most Au-F containing compounds, which is allowing for detailed examination of what is possible for the Au-F bond. In this presentation work to date conducted in our group on the reactivity of the Au(III)-F bond will be discussed.
These include direct C-H activation reactions, as well as an unexpected nucleophilic character to the bond.3
1. J. Miro, C. del Pozo, Chem. Rev. 2016, 116, 11924.
2. M. Albayer, R. Corbo, J. L. Dutton, Chem. Commun. 2018, 54, 6832
3. M. Albayer, N. Withanage, J. L. Dutton, Chemrxiv 2019,
41
EXTENDING ALKALI METAL MEDIATED MAGNESIATION FROM NITROGEN TO PHOSPHORUS
Michael A. Stevens1*, Phil C. Andrews1 and Victoria L. Blair1
1School of Chemistry, Monash University, Victoria, Australia Email: [email protected]
Metalation chemistry has been dominated by the alkyl lithiums and lithium secondary amides. Recently, there has been an emergence of bi-metallic superbases, combining the reactivity of an alkali metal with a metal of
higher electronegativity, such as magnesium, manganese or zinc, coined Alkali Metal Mediated Metalation.1 In
comparison to the wealth of knowledge on nitrogen based metalation chemistry, there has been comparatively
few studies on their heavier group 15 phosphorus analogues.2,3 The electronic properties conferred on compounds by the heavier elements can differ dramatically from the lighter ones.
Herein we report a comparative reactivity study of homologous nitrogen and phosphorus based compounds with
the sodium magnesiate complex [(TMEDA)Na(TMP)2Mg(CH2SiMe3)] 1. The magnesiated structures have been fully characterised by both single-crystal X-ray diffraction and NMR spectroscopy. The sodium magnesiate 1
has been found to offer rapid ‘atom efficient magnesiation’ of N-substituted indoles at ambient temperatures.4
The reactivity of the sodium magnesiate 1 towards phosphindoles was also explored, and found to be uniquely oxidation state dependent. Utilising these newly formed Mg-C bonds, we have examined their potential in in
situ iodolysis and Pd-catalysed cross-coupling reactions.
Figure 1: Contrasting molecular structures of phosphorus (III) and phosphorus (V) phenyl-phosphindoles to
the sodium magnesium base [(TMEDA)Na(TMP)(CH2SiMe3)Mg(TMP)]
(1) Mulvey, R. E. Acc. Chem. Res. 2009, 42 (6), 743–755.
(2) Blair, V. L.; Stevens, M. A.; Thompson, C. D. Chem. Commun. 2016, 52 (52), 8111–8114.
(3) Stevens, M. A.; Hashim, F. H.; Gwee, E. S. H.; Izgorodina, E. I.; Mulvey, R. E.; Blair, V. L. Chem. - A
Eur. J. 2018, 24 (58), 15669–15677.
(4) Stevens, M. A.; Blair, V. L. Eur. J. Inorg. Chem. 2018, 2018 (1), 74–79.
42
NUCLEOPHILIC ALUMINIUM: SYNTHESIS, STRUCTURAL AND REACTION CHEMISTRY OF THE ALUMINYL
ANION
Jamie Hicks1,2*, Petra Vasko2, Jose M. Goicoechea2 and Simon Aldridge2
1 Research School of Chemistry, Australian National University, 2601 2Chemistry Research Laboratory, 12 Mansfield Road, University of Oxford, OX1 3TA
Email: [email protected]
Aluminium is the most abundant metal in the Earth’s crust and is widely exploited in a number of key industrial processes. Being located in group 13 of the Periodic Table, it possesses four valence orbitals but only three valence electrons. Its reactivity is therefore dominated by its electron deficiency and electropositivity: Al(III) compounds are archetypal electrophiles. Last year, we reported that anionic Al(I) compounds can act as
nucleophiles, with the dimethylxanthene-stabilized potassium aluminyl compound [K{(NON)Al}]2.[1] The
complex has been shown to react in an unprecedented ‘umpolung’ fashion as an aluminium-centred nucleophile in the formation of a range of Al-E covalent bonds (E = H, C or metals), including in the synthesis of the first
nucleophilic gold compound [(NON)AlAuPtBu3].[2]
More recently, it has been found the potassium aluminyl and the related monormeric complex [K(2.2.2- crypt)][(NON)Al] show fascinating reactivity towards a range of small molecules, including simple arenes. Once such example is that the monomeric species was found to insert into the C-C bond of benzene to give the
7-membered heterocycle [K(2.2.2-crypt)][(NON)AlC6H6] (Figure 1).[3] This C-C bond activation of benzene was found to be reversible; mechanistic details and functionalisation of the C-C bond activation will be discussed.
tBu
Dipp
N
tBu Dipp
N
tBu
O Al O
25 °C, 48 hrs N
Dipp tBu
Al
N
Dipp
[(NON)Al]– [(NON)AlC6H6]–
Figure 1. C-C bond activation of benzene by a monomeric aluminyl complex.
References
[1] J. Hicks, P. Vasko, J. M. Goicoechea, S. Aldridge, Nature, 2018, 557, 92–95.
[2] J. Hicks, Akseli Mansikkamäki, P. Vasko, J. M. Goicoechea, S. Aldridge, Nature Chemistry, 2019, 11,
237–241.
[3] J. Hicks, P. Vasko, J. M. Goicoechea, S. Aldridge, J. Am. Chem. Soc. 2019, 141, 11000–11003.
43
STABILISATION OF CHIRAL SODIUM 1-AZA ALLYL AMIDE INTERMEDIATES FOR APPLICATION IN
ASYMMETRIC SYNTHESIS
J.A. Greer1, S.D. Bull2, V.L. Blair1 and P.C. Andrews1* 1Monash University, Victoria, Australia
2Bath University, Bath, UK Email: [email protected]
For many decades, synthetic chemistry has heavily relied on the use of organolithium reagents, particularly in
the form lithium amides. In recent years, work by the Andrews group has sought to uncover novel effects
occurring from the use of heavier alkali metals and/or higher denticity donors (such as TMEDA and PMDETA)
on the organic backbone of commonly used amides; chiral α-methylbenzylamine derivatives being of particular
interest. Results have ranged from anionic rearrangements leading to the formation of aza-allyl and aza-enolate
species,1 to more recent examples that have identified complete C-C cleavage.2 These effects commonly deviate
toward more highly conjugated systems and often lead to loss of chirality.
Our recent work has uncovered a variety of conditions that can better stabilize these intermediates allowing
them to be utilized in a variety of highly stereospecific reactions, which will be reported.3 This work
demonstrates not only that highly reactive Na species can potentially supplant Li, but also show unique
applications and reactivity, unachievable by classical organolithium based compounds.
References
1. P. C. Andrews, V. L. Blair, M. Koutsaplis and C. D. Thompson, Organometallics, 2012, 31, 8135-
8144.
2. P. C. Andrews, V. L. Blair, E. C. Border, A. C. Peatt, J. G. MacLellan and C. D. Thompson, Organometallics, 2013, 32, 7509-7519.
3. M. Koutsaplis, P. C. Andrews, S. D. Bull, P. J. Duggan, B. H. Fraser and P. Jensen, Chem. Commun., 2007, 3580-3582.
Li 6.94
K 39.098
Na 22.990
{[(PhCH)(2-PyrCH)N]Na•PMDETA}
44
DECORATING THE ROOM AT THE BOTTOM - DESIGNER NANOMATERIALS FOR CATALYTIC RENEWABLES
CONVERSIONS. Tony Masters
1*
1Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney,
NSW, Australia
Email: [email protected]
*“There’s plenty of room at the bottom”
*Richard Feynman, American Physical Society, Caltech, 29 December 1959
Feynman famously presaged the exploitation of the nanodomain in his 1959 lecture. His dreams from that era
are fast becoming reality as we learn to reproducibly control the synthesis of nanoarchitectures and exploit
their unique properties in fields as varied as medicine, physics, biology, optics, electronics and environmental
science.
This lecture describes several applications of nanomaterials as catalysts in the transformations of renewables.
The first example is the use of nanoparticulate Mo2C- and MoS2-based catalysts in the depolymerization and
deoxygenation of Kraft lignin in supercritical ethanol. A second example is our development of a novel form
of catalyst – porous liquid catalysts, exemplified by hydrogenation and Heck reactions. Another example is
the plasmonic enhancement of the photochemical hydrogen evolution reaction catalysed by silver
nanoparticles deposited on TiO2 grain boundaries. We have also been examining single MoS2 nanosheets as
catalysts and electrode materials, and the incorporation of nanoscience into the undergraduate laboratory.
Finally, we answer the question on everyone’s lips is “what does a nanoparticle actually look like? We use
atom-probe tomography (APT) to quantitatively determine the three-dimensional distribution of atoms within
a multimetallic core-shell nanoparticle with near-atomic resolution is described. In many of these examples,
the synthetic chemistry is manipulated and controlled by the use of ionic liquids to “lightly complex” growing
nanostructures, with the final example being the use of these properties to establish a world record
nanostructure in the development of high energy density batteries from abundant materials.
45
DEVELOPMENT OF POTASSIUM-ION BATTERIES
A.M. Glushenkov1,2* 1Research School of Chemistry, The Australian National University, Canberra,
ACT 2601, Australia 2 Research School of Electrical, Energy and Materials Engineering, The Australian
National University, Canberra, ACT 2601, Australia Email: [email protected]
Potassium-ion batteries represent one of the sustainable alternatives to the currently dominant lithium-ion
battery technology. This type of batteries offers high voltage cells based on naturally abundant ionic shuttle,
and the field develops very fast since 2015. The presentation will present the current status of the potassium-
ion battery development, with the focus on available electrode materials.
Graphite has emerged as a promising anode material in potassium-ion batteries.1-3 Similarly to its behaviour with lithium, it can reversibly intercalate potassium ions at low potentials. Other possible anode materials
(based on anticipated alloying4 and conversion-alloying reaction mechanisms5) are identified. It is revealed that the mechanisms of electrochemical reactivity with potassium are different from those established in lithium cells.
Metalorganic frameworks, layered and polyanionic inorganic compounds are currently investigated as cathode
materials by the community.6,7,8 In the later part of the talk, an overview of known cathode materials will be
presented and the openly available information on full cell battery prototypes will be discussed.
References
1. Z. Jian, W. Luo, X. Ji, J. Am. Chem. Soc. 2015, 137, 11566.
2. S. Komaba, T. Hasegawa, M. Dahbi, K. Kubota, Electrochem. Comm. 2015, 60, 172.
3. W. Luo, J. Wan, B. Ozdemir, W. Bao, Y. Chen, J. Dai, H Lin, Y. Xu, F. Gu, V. Barone, L. Hu, Nano Lett.
2015, 15, 7671.
4. I. Sultana, M.M. Rahman, Y. Chen, A.M. Glushenkov, Adv. Funct. Mater. 2018, 28, 1703857.
5. V. Lakshmi, Y. Chen, A.A. Mikhaylov, A.G. Medvedev, I. Sultana, M.M. Rahman, O. Lev, P.V.
Prikhodchenko, A.M. Glushenkov, Chem. Comm. 2017, 53, 8272.
6. A. Eftekhari, J. Power Sources 2004, 126, 221.
7. H. Kim, D.H. Seo, A. Urban, J. Lee, D.H. Kwon, S.H. Bo, T. Shi, J.K. Papp, B.D. McCloskey, G. Ceder,
Chem. Mater. 2018, 30, 6532.
8. T. Hosaka, T. Shimamura, K. Kubota, S. Komaba, Chem. Rec. 2019, 19, 735.
46
CHARACTERIZATION OF BATTERY MATERIALS USING X-RAYS
Milen Gateshki1, Marco Sommariva1, Gwilherm Nénert1, Thomas Degen1 and Olga Narygina2*
1Malvern Panalytical B.V., Almelo, The Netherlands 2Malvern Panalytical, a division of Spectris Pty, Sydney, NSW, Australia
Email: [email protected]
In operando cycling of P2-NaxFe1/2Mn1/2O2 battery cell. Data are courtesy of V. Duffort, E. Talaie and L.F.
Nazar, University of Waterloo, Canada.
X-ray diffraction and scattering techniques are powerful tools for the study of battery materials1, 2. In this work
we describe several X-ray methods, which can provide a wealth of information about new materials used in battery applications. By using X-ray diffraction (XRD) it is possible to identify the different crystallographic
phases, and with the Rietveld method3 it is possible to refine the crystallographic structures of the different materials and quantify the amount of each phase in the bulk material. It is also possible to perform in situ and
operando XRD measurements of the complete battery cells either in reflection or transmission geometry4-6. Study of complete battery cell in transmission geometry requires high energy radiation, e.g. Mo or Ag X-ray
anodes, and detector with high efficiency for corresponding photon. A newly developed Malvern Panalytical
X-ray detector (GaliPIX3D) allows for shorter measurement time and/or better data quality thanks to the higher
efficiency of the CdTe sensor material7. In addition, the short-range structure of crystalline, nano-crystalline and amorphous materials can be studied with the Pair Distribution Function method (PDF), based on a total scattering approach. All listed X-ray scattering and diffraction experiments can be performed on a single X-ray instrument, such as a Malvern Panalytical Empyrean multipurpose diffractometer.
1 E. Talaie V. Duffort, H. L. Smith, B. Fultz, L. F. Nazar. Energy Environ. Sci. 2015, 8, 2512. 2 Z. Liu, Y.-Y. Hu, M. T. Dunstan, H. Huo, X. Hao, H. Zou, G. Zhong, Y. Yang, C. P. Grey. Chem. Mat. 2014, 26(8), 2513. 3 H. M. Rietveld. J. Appl. Cryst. 1969, 2, 65. 4 I. Buchberger, S. Seidlmayer, A. Pokharel, M. Piana, J. Hattendorff, P. Kudejova, R. Gilles, H. A. Gasteiger. J. Electrochem. Soc. 2015, 162(14), A2737. 5 N. Sharma, W. K. Pang, Z. Guo, V. K. Peterson. ChemSusChem 2015, 8, 2826. 6 E. Talaie, P. Bonnick, X. Sun, Q. Pang, X. Liang, L. F. Nazar. Chem. Mat. 2016, DOI:
10.1021/acs.chemmater.6b02726. 7 G. Confalonieri, M. Dapiaggi, M. Sommariva, M. Gateshki, A. N. Fitch, A. Bernasconi. Powder Diff. J. 2015, 30(2), S65.
47
CALCIUM CARBONATE POLYMORPHS – THE ROLE OF IMPURITY IONS
F. Jones*1
1Curtin University, School of Molecular and Life Sciences, WA, Australia
Calcium carbonate is a mineral that is of interest for many reasons; it is a common biomineral1,2
, it is a scale
product and it is a mineral investigated for carbon sequestration purposes3,4
.
Biomineralisation is an important mechanism for many organisms to increase their survival. Biomineralisation
relies on the fact that the properties of the combined structure (mineral + organic components) are far superior
to the sum of the individual components. Calcium carbonate is a common biomineral for many sea creatures
and has been of much interest in terms of ocean acidification impacts. In addition, a situation can arise
whereby a calcium rich water may mix with a carbonate rich water leading to the formation of calcium
carbonate. This can lead to unwanted crystallisation and what is referred to as scale formation5. Controlling
scale formation is of interest in a wide variety of industries, especially where water is recycled. Finally,
calcium carbonate, as a solid, is a potential means by which CO2 can be sequestered out of the atmosphere and
stored geologically. Clearly, calcium carbonate and its formation needs to be fully understood.
Calcium carbonate has three anhydrous polymorphs; calcite, aragonite and vaterite with calcite being the
thermodynamically stable form. In pure systems it crystallises via a two-step process whereby an amorphous
solid forms first. This then goes through Ostwald rule of stages to eventually form calcite. However, both
aragonite (the metastable form) and calcite are often observed in seawater. There is much debate as to why
aragonite is stabilised in seawater but a comprehensive understanding is still lacking.
In this work, we explore the role of impurity ions and their impacts on the crystallization processes of
nucleation and/or growth, determine whether these impurity ions impact on the polymorph observed and
explore some of the possible mechanisms of aragonite stabilisation in seawater.
Figure 1. (a) SEM image and (b) overlaid phases detected from EBSD analysis for solids formed in synthetic
seawater
References
1. H. A. Lowenstam, S. Weiner. On Biomineralization. Oxford University Press; 1989. 75–76 p.
2. W. E. G. Müller, H. C. Schröder, X. Wang, Mar Drugs Rev. 2017, 15, 172.
3. R. Chang, S. Kim, S. Lee, S. Choi, M. Kim, Y. Park. Front Energy Res. 2017, 5, 1.
4. S. Lin , T. Kiga, Y. Wang, K. Nakayama. Energy Procedia. 2011, 4, 356.
5. S. Muryanto, A. P. Bayuseno, H. Ma’mun, M. Usamah, Jotho Procedia Chemistry 2014, 9, 69.
a b
48
<Figure>
BATTERY ELECTRODES AND MODULATED STRUCTURES: TWO WORLDS COLLIDE.
S. Schmid*,1
1School of Chemistry, The University of Sydney, NSW, Australia Email: [email protected]
Many electrode materials in rechargeable Li-ion (or other) batteries, follow a solid-solution mechanism during
the charge and discharge processes. The composition often changes over very large ranges while some phases essentially maintain their average structure type. This is strongly reminiscent of compositionally and
displacively flexible systems that form incommensurate composite structures1. The schematic above represents an electrode, with changing lithium concentration, whose structure is best described using a modulation function. Lithium ions are located where the modulation function (vertical centre) has maxima, with the wavelength changing continuously with lithium content (x).
Phases with such incommensurate structures are fascinating materials, which lack lattice periodicity but are still perfectly long-range ordered. Such systems exist across the whole range of chemical disciplines from organic
conductors to high-Tc superconductors and minerals2. The importance of modulated structures has been recognised, but there have been few systematic studies across composition ranges of wide-range solid solutions that form composite modulated structures.
Composite modulated crystals consist of two (or more) independent substructures that are mutually incommsurable in at least one dimension. Examples include urea inclusion compounds, columnar structures and
some layered structures with variable compositions3. For battery electrodes both the negative electrode, e.g. in the case of graphite, and the positive electrode, e.g. in the case of LiCoO2, can be considered as layered hosts (Cx layers and Co-O octahedral layers, respectively) in which Li ions are intercalated. In a composite structure regime, the Li arrangements can be considered one sub-structure and the host layers the other. This presentation
will explore evidence for modulated structures for a range of electrode materials and discuss the influence on their electrochemical performance.
1) R. L. Withers, S. Schmid and J. G. Thompson. Prog. Solid State Chem. 1998, 26, 1.
2) S. Schmid, R. L. Withers, R. Lifshitz (Eds., 2013), Aperiodic Crystals. Dordrecht: Springer.
3) S. Schmid, V. Fung. Aust. J. Chem. 2012, 65, 851.
49
Tuesday 17th
December
Session 1
50
TARGETED DELIVERY OF METAL COMPLEXES FOR PRECISION ONCOLOGY
Trevor W. Hambley1* 1School of Chemistry, University of Sydney, NSW 2006, Australia
Email: [email protected]
Precision oncology is a focus of most emerging approaches to cancer treatment. In this presentation, we will
argue that for metal-based cytotoxic agents to contribute fully to precision medicine-based approaches to cancer
treatment, strategies are required to focus their action, both to tumours themselves and to the various
microenvironments that exist within a solid tumour. Such approaches have the potential to reduce the side effects
that limit the application and effectiveness of cytotoxic anticancer agents and to generate more durable
outcomes.
Precision based approaches to cancer treatment can in principle be based on any features that characterise a
tumour and there have been a significant number of studies of using nutrient transporters to selectively deliver
platinum complexes to tumour cells that overexpress these transporters.1 However, there has been little
consideration given to using the profile of transporter expression or of protease activity in the tumour
environment for developing individualised treatment strategies.
We will report on our work aimed at developing low toxicity pro-drugs which exploit the biological features of
different tumour cell properties and the tumour environment with a particular focus on using transporter and
protease over-expression to selectively deliver platinum complexes to tumour cells (see Figure). The features
required in a complex and the effect of the coordination sphere on the stability and activation of platinum(IV)
prodrugs and cobalt(III) based drug delivery vehicles will be described as will examples of strategies for
achieving selective uptake of these complexes by cancer cells. We will also discuss the challenges to developing
biological systems that are able to replicate the effects of such complexes and establish their potential for use in
precision oncology.
Financial support by the Australian Research Council is gratefully acknowledged.
1. T.W. Hambley, J. Biol. Inorg. Chem. 2019, 24, 457.
51
RUTHENIUM(II)-ARENE THIOCARBOXYLATES: IDENTIFICATION OF A STABLE DIMER SELECTIVELY
CYTOTOXIC TO INVASIVE BREAST CANCER CELLS
L.J. Stephens1*, A. Levina2, M. Werrett1, V.L. Blair1, P.A. Lay2, and P.C. Andrews1
1Monash University, Vic, Australia 2University of Sydney, NSW, Australia Email: [email protected]
Ruthenium based complexes, which often exhibit lower toxicity in-vivo, are of high interest and hence offer an
attractive option to the existing Pt based anti-cancer drugs.1 NAMI-A and KP1019 are two Ru-based complexes
currently undergoing clinical trials to treat various forms of cancer, further demonstrating the potential use of
Ru-based compounds as anti-cancer agents (Figure 1).2 A more contemporary approach to Ru centered anti-
cancer agents has exploited ‘piano-stool’ complexes, often containing a para-cymene motif which helps to
stabilize the Ru (II) oxidation state.3 With this in mind we have developed a novel class of Ru (II) bifunctional
organometallic drugs for which subtle structural changes induce marked changes in activities against a variety
of cancer cell lines.
In vitro assays conducted on the 12 novel complexes have revealed that small structural changes in the complex
significantly impact their biological activity. Interestingly, one of the Ru complexes synthesised exhibits high
selectivity for in vitro models of aggressive breast cancers compared to other cultured cancerous and non-
cancerous cell lines. A number of other biological assays have revealed the high stability and selective
cytotoxicity of this Ru complex, further suggesting the novel compounds may possess good in vivo
pharmacokinetics with reduced side effects.
Figure 1. The two Ru (II) complexes; NAMI-A (left) and KP1019 (right) currently undergoing clinical trials.
1W. Ang, P. Dyson, Inorg Chem, 2006, 45, 9006-9013.
2I. Bratsos, E. Alessio, Metals in Medicine, 2007, 67, 692-696.
3A. Mondal, P. Paira, Curr. Org. Chem., 2018, 15, 179-207.
52
ANTIMICROBIAL COINAGE METAL N-HETEROCYCLIC CARBENE COMPLEXES
Zili Li,1 Joel C. Mather,1 Thomas P. Pell,1 David J. D. Wilson,1 Conor F. Hogan,1
Tatiana P. Soares da Costa2 and Peter J. Barnard1*
1Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University,
Bundoora, 3086, Australia.
2Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, 3086, Australia.
Email: [email protected]
We are interested in the synthesis, photophysical and bioinorganic properties of mono- and bi-metallic
coinage metal (Cu, Ag and Au) complexes of N-heterocyclic carbene (NHC) ligands. A series of homobimetallic complexes (Cu, Ag and Au) have been prepared from bridging NHC ligands and a versatile step-wise synthetic procedure has been developed for the preparation of heterobimetallic (Au-Ag, Au-Cu and
Au-Hg) complexes from symmetrical and also asymmetric bridging NHC ligands.1, 2 The bridging NHC
ligands support short metallophilic MM interactions and some of the complexes are luminescent.
The antimicrobial properties of Au(I)- and Ag(I)-1,2,4-Triazolylidene complexes were evaluated and the
Au(I) complexes showed good antimicrobial activity against two medically important strains of gram-positive
bacteria (Enterococcus faecium and Staphylococcus aureus), with the minimum inhibitory concentrations of
the active compounds being in the range 2 – 8 g/mL. Moderate antimicrobial activity was observed for the
Au(I) complexes against gram-negative bacterial strains, whilst the Ag(I) complexes displayed very low
antimicrobial properties against all strains tested.
References
1. T. P. Pell, D. J. D. Wilson, B. W. Skelton, J. L. Dutton and P. J. Barnard, Inorg. Chem., 2016, 55,
6882-6891.
2. T. P. Pell, B. D. Stringer, C. Tubaro, C. F. Hogan, D. J. D. Wilson and P. J. Barnard, Eur. J. Inorg.
Chem., 2017, 2017, 3661-3674.
53
INFLUENCE OF LIPOPHILICITY ON CELLULAR ACCUMULATION AND ANTICANCER ACTIVITY OF
UNCONVENTIONAL PLATINUM(IV) PRODRUGS
Krishant M. Deo1*, Jennette Sakoff2, Jayne Gilbert2, Yingjie Zhang3 and Janice Aldrich-Wright1
1Nanoscale Organisation and Dynamics Group, School of Science and Health, Western Sydney University,
Campbelltown, Australia 2Calvary Mater Newcastle, Waratah, Australia
3Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
Email: [email protected]
Figure 1: Cellular uptake of lipophilic and hydrophilic platinum(IV) derivatives.
Clinically used platinum(II)-based anticancer agents exhibit similar structural characteristics and as such, they are hindered by similar limitations (toxicity and intrinsic/acquired resistance to therapy), attributed to their
covalent binding mechanism of action (MoA).1
Efforts to circumvent these limitations has prompted the development of structurally diverse compounds that exhibit different MoA(s). A potent class of platinum(II)
anticancer complexes have been developed of the type, [Pt(HL)(AL)]2+
(HL = 1,10-phenanthroline or 5,6- dimethyl-1,10-phenanthroline; AL = 1S,2S-diaminocyclohexane), where a multimodal MoA was ascribed to their potent activity including a reduction in mitochondrial membrane potential; induction of epigenetic
processes and changes to the cytoskeletal architecture.2 In vivo studies revealed reduced efficacy due to poor
pharmacokinetics, however, this was improved with the development of di-hydroxo platinum(IV) complexes,
via oxidation of the platinum(II) species.3
To further enhance the pharmacokinetics, a series of increasingly
lipophilic platinum(IV) complexes were synthesised, [Pt(HL)(AL)(OH)(R)]2+
and [Pt(HL)(AL)(R)2]2+
(R = increasingly lipophilic carboxylate axial ligands), with the explicit intent to improve cellular accumulation. Although nanomolar in vitro cytotoxicity (3.4 nM against Du145 prostate cancer) and an increase in cellular accumulation were observed, there was no clear correlation between increasing lipophilicity, cellular
accumulation and cytotoxicity.4
1. L. Galluzzi, L. Senovilla, I. Vitale, J. Michels, I. Martins, O. Kepp, M. Castedo and G. Kroemer,
Oncogene, 2012, 31, 1869-1883.
2. H. Kostrhunova, J. Zajac, V. Novohradsky, J. Kasparkova, J. Malina, J. R. Aldrich-Wright, E.
Petruzzella, R. Sirota, D. Gibson and V. Brabec, J. Med. Chem., 2019, 62, 5176-5190.
3. B. W. J. Harper, E. Petruzzella, R. Sirota, F. F. Faccioli, J. R. Aldrich-Wright, V. Gandin and D.
Gibson, Dalton Trans., 2017, 46, 7005-7019.
4. K. M. Deo, J. Sakoff, J. Gilbert, Y. Zhang and J. R. Aldrich-Wright, Dalton Trans., 2019, DOI:
10.1039/C9DT03339D.
54
H H N N
H Cu H N N
N N H H
T
K
THERANOSTIC COPPER RADIOPHARMACEUTCALS: DIAGNOSTIC IMAGING AND TARGETED THERAPY OF
NEUROENDOCRINE TUMOURS AND PROSTATE CANCER
Paul S. Donnelly*
1School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, 3010, Australia
Email: [email protected]
The principle of using the same molecule for both diagnosis and therapy is called ‘theranostics’. The
use of a ‘matched pair’ of copper radionuclides to develop new theranostic agents will be presented. Copper-64
is a positron-emitting radionuclide that can be used for diagnostic imaging while copper-67 is a beta-emitting
radionuclide that can be used for targeted radiotherapy. The use a copper-binding chelator that forms
exceptionally stable complexes with copper that is tethered to peptides that bind to receptors over-expressed on
tumour tissue will be presented. These new agents can be used for diagnostic imaging with copper-64 and
targeted therapy with copper-67.
Specific examples will include the use of peptides that selectively bind to somatostatin receptors that
are over-expressed in certain neuroendocrine tumours and prostate specific membrane antigen that is over-
expressed in metastatic prostate cancer (Figure 1). The synthesis of the new agents. their pre-clinical evaluation
in cancer models and first in human clinical trials will be presented.
Labelling antibodies with radioactive isotopes can combine the diagnostic and therapeutic possibilities
of nuclear medicine with the selectivity of antibody targeting. Antibodies labelled with positron-emitting
radioactive isotopes can be used as tracers for PET imaging and are of interest as companion diagnostics to
therapeutic antibodies. Strategies to radiolabel antibodies and antibody fragments with copper radionuclides
using site-specific enzyme mediated bioconjugation will be presented as will the in vivo evaluation of the new
constructs in cancer models.
a)
O H
N
HN
O OH O
O
H H N N
N H
O O
O
H H H
N N N
N
O O H
O
O
NH
HO O
O
HO OH N N
Cu(SarbisPSMA)
O
HO OH N N
O H H O
b) O
H H O
1 hr 4 hr 24 hr
Figure 1. a) The chemical structure of Cu(SarbisPSMA). b) PET/CT images of LNCap-tumor-bearing NSG mice following injection of [64Cu]CuSarbisPSMA (2– 3 MBq) (T = Tumour; K = Kidney).
55
ROOM TEMPERATURE SPIN CROSSOVER IN ‘HYBRID’ COORDINATION POLYMERS
Lida Ezzedinloo1, Katrina A. Zenere,2 Helen Brand,3 Jack K. Clegg4 and Suzanne M. Neville1* 1School of Chemistry, UNSW Sydney, NSW, Australia
2School of Chemistry, The University of Sydney, NSW, Australia 3The Australian Synchrotron, ANSTO, VIC, Australia.
4School of Chemistry and Molecular Biosciences, UQ, QLD, Australia. Email: [email protected]
Driven by the applicability of molecular switching materials towards diverse applications such as chemical
switching, molecular sensing, and information storage, our understanding of coordination materials has progressed substantially over the past few decades. Externally addressable spin-state switching materials are a prime example of molecular switching. There are two families which have been the subject of extensive studies as they show characteristics beneficial for applications, such as ambient switching and high cooperativity (i.e.,
hysteresis). The first is 1-D chain species formed by the linkage of FeII sites by 1,2-1,2,4-triazole ligands (Figure (a)) which show cooperative spin transitions, often occurring at room temperature. The second family are
Hofmann-type frameworks, which are layered 2- or 3-D networks - the layers are formed by the bridging of FeII
sites by linear or square planar metallocyanide ligands (Figure (b)) and are stacked (2-D) or joined (3-D) by choice of axial aromatic ligands. We present a new family of spin crossover (SCO) active materials which can be considered as ‘hybrid’ between these highly acclaimed spin-state switchable families (Figure (c)).
Importantly, cooperative and room temperature switching is maintained in these hybrid species as per the parent families alongside ambient guest-sensing properties.
Figure. Components of (a) 1-D 1,2,4-triazole chains and (b) 2-D Hofmann frameworks used to form (c) a
novel spin crossover coordination polymer.
56
TUNABLE POROUS COORDINATION POLYMERS FOR SCAVENGING WASTE ANAESTHETIC VAPOURS
Keith F. White1,2*, Brendan F. Abrahams2, Ravichandar Babarao3, A. David Dharma2, Helen. E.
Maynard Casely4, Forbes. McGain5 and Richard Robson2
1School of Molecular Science, La Trobe University, Wodonga, VIC, Australia 2School of Chemistry, University of Melbourne, Parkville, VIC, Australia
3School of Science, RMIT University, Melbourne, VIC, Australia 4Australian Centre for Neutron Scattering, ANSTO, Menai, NSW, Australia
5Western Health Sunshine Hospital, St Albans, VIC, Australia Email: [email protected]
Figure 1. A subset of the structurally related family Zn(L) coordination polymers along with the Zn2+
bridging phenolic acids (LH2) incorporated in its synthesis Patients undergoing general anaesthesia metabolise less than 5 % of volatile anaesthetic (VA) agents delivered
during their procedure, unmetabolized vapours are exhaled and extracted to the atmosphere. Widely used VA’s:
nitrous oxide and fluorinated ethers: isoflurane, sevoflurane and desflurane are hundreds to thousands of times
more potent greenhouse gases than carbon dioxide.1 The impact of VA emissions from medical procedures in
the United States alone is measured to have a global warming potential comparable to approximately one million
passenger cars.2 In the pursuit of more sustainable practices, the medical community is interested in technologies
that provide ‘in theatre’ scavenging of VA vapours and their subsequent release for reuse. Coordination
polymers, a class of crystalline material containing metal centres bridged by multi-dentate ligands in infinite
network structures, appear well suited to the role of capture and recovery of waste VA’s owing to (a) the
potential to generate porous networks with high surface areas onto which gases can be sorbed and (b) the
possibility to adapt coordination a polymer network during its synthesis to provide channel structures that meet
the demands of a target guest molecule.
In this work we describe the synthesis of a family of structurally related porous, Zn(L), coordination polymers
where L = the dianion of phenolic acids like those seen in 1, 2 and 3. The channel structure of the Zn(L)
compounds is predetermined by the choice of phenolic acid employed in its synthesis. We have prepared a
catalogue of porous Zn(L) compounds with different channel structures that provide a suite of guest uptake
properties including remarkably high affinity for fluorinated ethers or the exclusion of some gases into the
compounds intraframework voids. ‘In theatre’ trials of a waste VA scavenging device that incorporates a Zn(L)
compound show that the device can capture and isolate outgoing VA’s.
1. Y. Ishizawa, Anesthesia & Analgesia, 2011, 112, 213-217. 2. M. Sulbaek Andersen, S. Sander, O. Nielsen, D. Wagner, T. Sanford Jr and T. Wallington, British
journal of anaesthesia, 2010, 105, 760-766.
57
HYDROGEN BONDED FRAMEWORKS PREPARED IN WATER: SYNTHESIS, SWITCHING BEHAVIOUR AND
ENZYME ENCAPSULATION
Nicholas G. White Research School of Chemistry, The Australian National University, Canberra, ACT, Australia
We have developed a predictable and modular synthesis of a family of supramolecular frameworks,
which are assembled through charge-assisted hydrogen bonds between amidinium cations and
carboxylate anions.1 These frameworks are prepared in water, and are stable to water, polar organic
solvents and heating.2
The frameworks show interesting switching behaviour where several polymorphs of a given
framework can be accessed by addition of various stimuli. Additionally, with collaborators at the
University of Adelaide and TU Graz, we have recently shown that these frameworks can be used to
encapsulate enzymes. The resulting framework-enzyme composites show enhanced stability to
temperature, organic solvents, proteolytic and denaturing agents while retaining their catalytic
activity.3
1 M. Morshedi, M. Thomas, A. Tarzia, C. J. Doonan and N. G. White, Chem. Sci. 2017, 8, 3019. 2 S. A. Boer, M. Morshedi, A. Tarzia, C. J. Doonan and N. G. White, Chem. Eur. J. 2019, 25, 10006. 3 W. Liang, F. Carraro, M. B. Solomon, S. G. Bell, H. Amenitsch, C. J. Sumby, N. G. White, P. Falcaro and N.
G. White, J. Am. Chem. Soc. 2019, 141, 14298.
58
HYDROCARBON ADSORPTION WITHIN MOFS CONTAINING A CONTOURED, ALIPHATIC PORE
ENVIRONMENT
Lauren K. Macreadie1*, Matthew R. Hill.2 and Shane G. Telfer1
1Massey University, Palmerston North, New Zealand 2CSIRO, Australia, Clayton, VIC 3168
Email: [email protected]
Aromatic ligands, with polycarboxylate or multitopic functionalities, govern the synthetic chemists’ toolbox when forming metal-organic frameworks (MOFs) due to their rigid nature, commercial availability and the numerous variable coordination modes exhibited by these functionalities. Conversely, despite their extensive
success in creating a rich foundation for the development of new and archetypal MOFs, restriction to solely phenyl interactions within adsorbates represents a possible limitation and reduced variation in the pore chemical
environment of the materials.1 Separation of hydrocarbons using low energy processes is a key area from an industrial standpoint where the strategic design of the MOF pore chemical environment can avoid energy
expensive separations based on changes of phase.2
Cubane-1,4-dicarboxylic acid (1,4-H2cdc) is a rigid, aliphatic dicarboxylate linker that contains eight carbon atoms arranged in a near-perfect cubic arrangement. Of notable interest is the structural similarity between 1,4-
H2cdc and benzene-1,4-dicarboxylic acid (1,4-H2bdc) – providing significant scope for the employment of the
cubane molecule in MOF synthesis.3 Through the incorporation of 1,4-H2cdc into prominent MOF architectures,
we demonstrate the striking effects a contoured, aliphatic pore environment has on gas and hydrocarbon adsorption, compared with its aromatic counterpart, and explore the potential separation capacities these
frameworks may pose.1 Here we present a single-component ([Zn4O(1,4-cdc)3]n, CUB-5) and a multi-
component (Zn4O(hmtt)4/3(bpdc)1/2(cdc)1/2]n, CUB-30) MOF material which contain 1,4-H2cdc as an aliphatic linker. The stark difference in vapour adsorption between the topologically analogous frameworks highlights
the importance of pore shape during the adsorption process.1 Interestingly, both MOFs show promise for
tuneable, selective hydrocarbon adsorption at low pressures, where CUB-5 shows a propensity for benzene adsorption at low partial pressures, providing a promising landscape for future investigations into benzene separations from an industrial standpoint.
References
[1] L.K. Macreadie, E.J. Mensforth, R. Babaao, K. Konstas, S.G. Telfer, C.M. Doherty, J. Tsanaktsidis,
S.R. Batten, M.R. Hill, J. Am. Chem. Soc. 141, 3828, 2019.
[2] A. Karmakar, P. Samanta, A.V. Desai, S.K. Ghosh, Acc. Chem. Res. 50, 2457, 2017. [3] M. Eddaoudi, J. Kim, D. Vodak, A. Sudik, J. Wachter, M. O’Keeffe, O.M. Yaghi, Proc. Natl. Acad.
Sci. U. S. A. 99, 4900, 2002.
59
N
N
LANTHANIDE-BASED METALLOSUPRAMOLECULAR MATERIALS
Alex T. O’Neil, and Jonathan A. Kitchen* 1Chemistry, School of Natural and Computational Science, Massey University Albany, Auckland, New Zealand
Email: [email protected]
R R
N N
N N
N N
HN HN
O 0.33 eq O
Ln(CF3SO3)3!H2O
N Ln3+
O O
HN HN
N N
N N N
R R 3
Developing functional supramolecular materials from simple building blocks is an active area of research. To this end, the use of f-metal ions to direct the synthesis of such complex self-assembly supramolecular systems using organic ligands has become a popular method whereby the interesting magnetic and photophysical
properties of the lanthanides can also be exploited.1,2 Application for such systems include molecular sensors, solar cell enhancers, bio-probes, security inks, drug delivery systems, smart materials for healthcare and advanced materials for next generation electronics/spintronics.3 This presentation will focus on our recent
efforts to develop novel 2,6-pyridinedicarboxamide4 based ligands that can be readily functionalized using click chemistry. Using this approach, we can develop systems that assemble around lanthanide ions (typically we
use the luminescent Tb3+ and Eu3+ ions) and then further assemble into more complex systems including large
multi-metallic architectures, mixed d-block/f-block assemblies, mono-/multi- layered thin films prepared using Langmuir-based techniques, dual emissive assemblies and other luminescent soft materials (gels, polymers
etc.).5,6
1. J.-C. G. Bünzli, Acc. Chem. Res. 2006, 39, 53.
2. J.-C. G. Bünzli, C. Piguet, Chem. Soc. Rev. 2005, 34, 1048
3. D. B. Amabilino, D. K. Smith and J. W. Steed, Chem. Soc. Rev., 2017, 46, 2404
4. J. A. Kitchen, Coord. Chem. Rev. 2017, 340, 232
5. A. B. Carter, R. J. Laverick, D. J. Wales, S. O. Akponasa, A. J. Scott, T. D. Keene, J. A. Kitchen, Cryst.
Growth Des., 2017, 17, 5129 6. D.J. Wales, J.A. Kitchen, Chem. Cent. J. 2016, 10, 72
60
PR2
Ir
PR2
PR2
Ir
PR2
ELECTRON RICH PCCARBENEP IRIDIUM COMPLEXES FOR RAPID CATALYTIC H/D EXCHANGE
Joel D. Smith1
and Warren E. Piers1*
1University of Calgary, Calgary, Alberta, Canada
Email: [email protected]
Me2N
OH OH OH
Me2N
H/D Exchange Catalyst
Facile, selective deuteration (and by extension, tritiation) of organic molecules is important for establishing
adsorption, distribution, metabolic and excretion (ADME) pathways for drug discovery and registration. In
2012 we introduced the PCcarbeneP ligand with aryl linkers and electron rich alkyl groups on phosphorus and
have explored its chemistry for a variety of late transition metals. The parent iridium complexes were
observed to undergo ligand deuteration in C6D6 at the aryl C-H bonds under certain conditions. In efforts to
increase the donor strength of the ligands, we introduced a linker for the two aryl groups to rigidify the ligand
and incorporated donating NMe2 groups para to the carbene donor. This ligand is extremely electron rich and
stabilizes Ir(V) intermediates. The polyhydride and hydroxide iridium complexes of this ligand are extremely
effective H/D exchange catalysts using benzene or D2O as a deuterium source. The characterization of the
active polyhydride will be described and the mechanism of H/D exchange will be discussed, as well as a brief
overview of the substrate scope of the process.
PR2
Ir
PR2
61
CATALYSTS FOR CO2 REDUCTION – CAPTURE: FROM MECHANISTIC STUDY TO HETEROGENEOUS CATALYSIS
Biswanath Das1*, Lida Ezzedinloo1, Mohan Bhadbhade2, Stephen B. Colbran1 and Graham E. Ball1
1 School of Chemistry, University of New South Wales, Sydney 2052, Australia, 2 Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia
Email: [email protected]
The carbon dioxide concentration in Earth's atmosphere has reached an alarming level.1,2 As non-fossil and renewable energy sources are yet to fulfil the energy demand of the 21st century, one of the most efficient ways
to regulate the amount of CO2 in the atmosphere would be to capture emitted CO2 and transform it into fuel and
commodity materials.3,4 Understanding structural features of molecular catalysts for carbon dioxide reduction –
capture is essential for mitigating CO2 emission, as well as for developing next generation catalytic systems renewable energy purpose. We have developed a series of active molecular catalysts containing first and second row transition metal elements and our recent findings are as follows:
i) atmospheric carbon dioxide (low concentration) can be utilized to develop new
chemicals/catalysts/compounds using first row transition metals, provided a proper reaction condition.5
ii) certain molecular design can bring in high product selectivity of carbon dioxide electroreduction
iii) smart changes in the first coordination sphere of the molecular catalysts can impact in drastic drop in over
potential
iv) we can corelate homogeneous and heterogeneous (on reduced graphene oxide) CO2 reduction activity to a
good extent
To become practical, the renewable energy research field demands interdisciplinary research, more precisely an
environment where chemist, physicist and material engineers will work together to realize the next generation
of high performance, cutting-edge catalytic systems. A good understanding at the molecular level and a proper
knowledge in materials engineering will help us to reach our goal.
1 D. Schimel, B. B. Stephens and J. B. Fisher, Proc. Natl. Acad. Sci. U. S. A., 2015, 112, 436. 2. K. Zickfeld, S. Solomon and D. M. Gilford, Proc. Natl. Acad. Sci. U. S. A., 2017, 114, 657.
3. E. Alper and O. Yuksel Orhan, Petroleum, 2017, 3, 109.
4. P. Kang, Z. Chen, A. Nayak, S. Zhang and T. J. Meyer, Energy Environ. Sci., 2014, 7, 4007.
5. B. Das, M. Bhadbhade, A. Thapper, C. D. Ling, S. B. Colbran Dalton Trans 2019, 48, 3576.
62
N R
NHC-IRIDIUM COMPLEXES FOR ASYMMETRIC HYDROAMINATION REACTIONS
D. Foster1, P. Gao
1, G. Sipos
1, and Reto Dorta
1*
1School of Molecular Sciences, The University of Western Australia, WA, Australia
Email: [email protected]
Catalysts
or
Products
R R
N N FG FG
FG
R
N
FG
Optically active N-heterocyclic compounds are of prime importance in commodity and specialty chemicals
and are often present in natural products and medicines. One of the most elegant, perfectly atom-economical
ways of producing such compounds is through the use of an enantioselective olefin hydroamination reaction
starting from the appropriate aminoolefin precursor molecules.1
Herein, we provide a brief account of our studies using [Ir(NHC*)(COD)] catalysts in the asymmetric
intramolecular hydroamination of unactivated aminoolefins. Scope, limitations and likely processes at play for
formation and enantioselection of the products will be discussed.
Reference:
1) L. Huang, M. Arndt, K. Gooßen, H. Heydt, L. J. Gooßen Chem. Rev. 2015, 115, 2596.
Ph Ph [X]
N N
Cy
Ir Cy
Cy
Cy
[X]
N N
Cy
Ir Cy
Cy
Cy
FG N
R
63
DEVELOPING NEW SYNTHETIC METHODLOGY: TRANSITION METAL CATALYSIS, PHOTOCATALYSIS AND
DUAL CATALYTIC STRATEGIES
Sinead T. Keaveney Department of Molecular Sciences, Macquarie University, North Ryde, NSW 2109, Australia
Email: [email protected]
Complex organic compounds are ubiquitous in the pharmaceutical, agrochemical and materials chemistry
industries, with these compounds often featuring a diverse range of functional groups. To meet the continuing
demand for efficient, sustainable and selective strategies to access complex organic compounds, our toolbox
of synthetic methods needs to continually expand.1
To address this challenge, my research focuses on developing new, or more efficient, chemical transformations.
Recent work has focused on applied organometallic catalysis, where catalyst design and mechanistic investigations can allow new synthetic methods to be developed. In particular, I am interested in rationally designing catalysts to facilitate challenging and high-value chemical transformations, such as the
incorporation of the trifluoromethyl group using palladium catalysis2
and the development of chemoselective
cross-coupling protocols using an air-stable palladium(I) dimer.3
Ongoing work is focused on designing
catalysts for efficient C-F activation, so that a mild and generally applicable C-F functionalisation protocol can be developed. Another important area of catalysis is the development of synthetic protocols that utilise
visible light to fuel chemical transformations.4,5
We are particularly interested in combining photocatalysts
with typical heat activated transition metal catalysts, to allow unique chemical reactivity to be developed
using these ‘tethered dual catalysts’. 6,7
Designing new synthe,c methodology
Developing tethered dual photo – transi,on metal catalysts
[1] Zhou, Q.-L., Angew. Chem. Int. Ed. 2016, 55, 5352
[2] Keaveney, S. T.; Schoenebeck, F., Angew. Chem. Int. Ed. 2018, 57, 4073
[3] Keaveney, S. T.; Kundu, G.; Schoenebeck, F., Angew. Chem. Int. Ed. 2018, 57, 12573
[4] Marzo, L.; Pagire, S. K.; Reiser, O.; König, B., Angew. Chem. Int. Ed. 2018, 57, 10034
[5] Michelin, C.; Hoffmann, N., ACS Catal. 2018, 8, 12046
[6] Wang, D.; Pernik, I.; Malmberg, R.; Venkatesan, K.; Prasad, S.; Schmidt, T.; Keaveney, S. T.; Messerle,
B. A., manuscript under review.
[7] Wang, D.; Solomon, N. S.; Pernik, I.; Messerle, B. A.; Keaveney, S. T. manuscript under review.
BArF4
B
PPh3
Pd I
PPh3
BArF4
N N F B
N
N N N B
N N F
N N Ir
Cp*
Cl
Ir N N N N
F F F F OC CO
O
R
Pd/XantPhos F
Et3Si-CF3
CF3
R Cl
OTf Pd(I) dimer
R-ZnCl
R
Cl
F Ni catalyst
MeO3Si-R
or B(OH)2-R
R
R R
64
SYNTHESIS AND TRANSITION METAL-CATALYSED REACTIVITY OF ALLENYLOXAZOLIDINONES
Farzad Zamani1, Ronald Brown1, Rasool Babaahmadi2, Alireza Ariafard2, Brian Yates2, Michael
Gardiner2, Stephen G. Pyne1, and Christopher Hyland1* 1University of Wollongong, Wollongong, NSW, Australia
2University of Tasmania, Hobart, TAS, Australia
Email: [email protected]
Leading on from our work on Pd-catalysed dearomative [3 + 2] cycloaddition reactions of vinylaziridines1 we
have designed and prepared the homologous allenyloxazolidinones.2 In this presentation, our previous work on the development of dearomative cycloaddition reactions involving vinylaziridines will be discussed as a background to the newly-developed divergent reactivity of these allenyl oxazolidinones with boronic acids
under palladium(0) catalysis.3 These reactions give rise to either substituted 1,3-dienes or vinyl oxazolidinones
by virtue of a simple switch in additive. Critically, the products are obtained in good to excellent yields and in a highly regioselective and enantioretentive manner. Both of the resulting products are perfectly suited to undergo further reactions to form more complex, medicinally-relevant heterocycles. The addition of an alkene tether to the diene results in Type I intramolecular Diels–Alder reactions to give novel, steroid-like polycycles.
The discovery and optimisation of the Pd(0)-catalysed reactions will be presented, as well as the reaction scope
and applications of these products in the synthesis of more complex scaffolds. The underlying reaction
mechanisms will also be discussed, revealing how the divergent reactivity of the allenyloxazolidinones could
be harnessed to fashion the synthetic tools required for the construction of complex, pharmaceutically-relevant
heterocycles. The transformation of allenyloxazolidinones into chiral enynes and their subsequent gold-
catalyzed aromatisation chemistry will also be presented.
References
1. D. J. Rivinoja, Y. S. Gee, M. G. Gardiner, J. H. Ryan, C. J. T. Hyland. ACS Catalysis, 2017, 7, 1053–
1056.
2. a. F. Zamani, F.; S. G. Pyne, C. J. T. Hyland. J. Org. Chem., 2017, 82, 6819-683. b. F. Zamani, F. R.
Babaahmadi, B. F. Yates, M. G. Gardiner, A. Ariafard, S. G. Pyne, C. J. T. Hyland. Angew. Chemie. Int. Ed.
2019, 58, 2114-2119.
3. R. B. Brown, F. Zamani, M. G. Gardiner, S. G. Pyne, C. J. T. Hyland. Chemical Science, 2019, DOI:
10.1039/C9SC03215K
65
MLCT AND ILCT STATES IN RHENIUM(I) COMPLEXES
Keith C. Gordon*1
1University of Otago, Chemistry Department, Dunedin, New Zealand 2Name of organisation of the second author, Palmerston North, New Zealand
Email: [email protected]
Metal complexes with ligands that have charge-transfer electronic structure can lead to interesting interplay between metal-to-ligand and intra-ligand charge transfer excited states (MLCT and ILCT respectively). In a systematic study of [ReCl(CO)3(dppz-(linker)-TPA)] complexes (ligand shown above), we find a long-lived excited state that is 3ILCT in nature. This is characterized through transient absorption and emission, transient resonance Raman (TR2), time-resolved infrared (TRIR) spectroscopy and TDDFT calculations. Modulation of the donor and acceptor energies results in changes of the 3ILCT lifetime by one order of magnitude, ranging from 6.1 (± 1) µs when a diphenylamine donor is used to 0.6 (± 0.2) µs when a triazole linker and triphenylamine
donor is used. The excited state lifetime may be rationalized by consideration of the driving force within the
framework of Marcus theory, and appears insensitive to the nature of the linker.1,2
However we show in studies of ILCT systems with 1,10-phanthroline ligands the interactions between the MLCT and ILCT states is stronger leading to unpredictable behaviour. For example simple donor tuning using electron withdrawing and donating groups results in emission spectra that appear unchanged with substituent
yet actually arise from different states.3
[1] C. B. Larsen, H. van der Salin, G. E. Shillito, N. T. Lucas, K. C. Gordon,. Inorg. Chem. 2016, 55, 8446.
doi: 10.1021/acs.inorgchem.6b01039
[2] B. S. Adams, G. E. Shillito, H. van der Salm, R. Horvath, C. B. Larsen, X. Z. Sun, N. T. Lucas, M. W.
George and K. C. Gordon, Inorg. Chem. 2017, 56, 12967. doi: 10.1021/acs.inorgchem.7b01710 [3] G. E. Shillito, T. B. J. Hall, D. Preston, P. Traber, L. J. Wu, K. E. A. Reynolds, R. Horvath, X. Z. Sun, N.
T. Lucas, J. D. Crowley, M. W. George, S. Kupfer K. C. Gordon J. Am. Chem. Soc. 2018, 140, 4534. doi:
10.1021/jacs.7b12868
66
EXCHANGE COUPLING IN A CO(II)-RADICAL COMPLEX
Gemma K. Gransbury1*, Marie-Emmanuelle Boulon2, Richard A. Mole3, Robert W. Gable1, Boujemaa Moubaraki4, Keith Murray4, Lorenzo Sorace2, Alessandro Soncini1 and Colette Boskovic1
1University of Melbourne, VIC, Australia 2University of Florence, FI, Italy
3Australian Nuclear Science and Technology Organisation, NSW, Australia 4Monash University, VIC, Australia
Email: [email protected]
High spin (HS) cobalt(II)-radical complexes are components of new magnetic and multi-functional materials
including those displaying single-molecule magnet, single-chain magnet, long-range magnetic ordering, spin-
crossover and valence tautomeric behaviours. The rational design of optimised materials requires a
comprehensive understanding of the correlation between molecular and electronic structure. For example, in
spintronics, metal-radical exchange has been shown to mediate interface interactions within devices.1 Despite
the importance of Co(II)-radical coupling, it is rarely investigated due to the difficulties of modelling an orbitally
degenerate ground state, with spin-orbit coupling, single-ion anisotropy, competing exchange pathways and a
potentially anisotropic exchange interaction.
We present a combined experimental and computational study on the electronic structure of a Co(II)-
semiquinonate (sq–) complex, which represents the high temperature state of a cobalt-dioxolene valence
tautomeric transition. Our approach builds up from the single-ion anisotropy of the isolated HS Co(II) ion, to
then include intramolecular metal-radical coupling and finally intermolecular exchange interactions. This
approach uses ab initio computational methods and an empirical exchange model to reproduce both
spectroscopic (inelastic neutron scattering) and magnetometry data. The single-ion anisotropy of the HS Co(II)
species in the absence of the radical has been identified by ab initio computational methods and comparison to
HS Co(II) analogues with diamagnetic ligands. Ab initio calculations afford excellent reproduction of both
magnetic and EPR data of the analogue complexes.
Using the method outlined above, we have elucidated the exchange interactions in the HS Co(II)-sq complex.
We found the intramolecular exchange to be anisotropic, with antiferromagnetic x- and y-components to the
exchange and a ferromagnetic z-component, resulting in a dominant ferromagnetic contribution to the ground
state.2 The exchange interaction contains significant contributions from spin-orbit coupling and is of a similar
magnitude to the distortions from octahedral geometry. This approach has enabled us to answer the long-debated
question about the nature of exchange in Co(II)-sq systems for a specific case and may be generalised to
determining exchange in orbitally degenerate metal ion-radical systems.
1. A. Candini, D. Klar, S. Marocchi, V. Corradini, R. Biagi, V. De Renzi, U. del Pennino, F. Troiani, V.
Bellini, S. Klyatskaya, M. Ruben, K. Kummer, N. B. Brookes, H. Huang, A. Soncini, H. Wende, M.
Affronte, Sci. Rep. 2016, 6, 21740.
2. G. K. Gransbury, M.-E. Boulon, R. W. Gable, R. A. Mole, B. Moubaraki, K. S. Murray, L. Sorace, A.
Soncini, C. Boskovic, Chem. Sci. 2019, 10, 8855-8871.
67
TRANSITION METAL–ORGANIC HYDRIDE DONOR CONJUGATES FOR
ELECTROCATALYSIS OF REDUCTION OF CARBON DIOXIDE
S.B. Colbran* UNSW Sydney, NSW, Australia Email: [email protected]
+
We hypothesized that conjugates (L'nML~OHD-H) formed from appropriate positioning of reactive transition
metal centres (L'nML) and organic donors of hydride ion (OHD-H) should display efficacious synergic activities
in catalyses of reduction of organic and inorganic substrates.1 Testing this concept led to demonstrations of
efficient biomimetic catalysts for chemical reduction of organic substrates.2,3 In this talk I will describe attempts
to extend this notion—figure, left-side—to the electrochemical reduction of carbon dioxide (undertaken for all
the obvious reasons).1,4-7 Results include: (i) some pretty coordination chemistry—e.g., figure; (ii) much effort,
pain, for, in some cases, not much gain and, in others, total failure; (iii) disabuse of a prevalent belief that
(dihydro)pyridine is an electrocatalyst for CO2 reduction; (iv) salutary tales: decomposed catalysts and free
ligands that work better than the parent molecular ‘catalysts’, including beyond the usual two-electron barrier
for molecular catalysts to afford the 8-electron reduction product, methane.
1. A. McSkimming, S. B. Colbran, ‘The coordination chemistry of organo-hydride donors: new prospects for efficient
multi-electron reduction’, Chem. Soc. Rev., 2013, 42, 5439-5488
2. A. McSkimming, M. M. Bhadbhade, S. B. Colbran, ‘Bio-inspired catalytic imine reduction by rhodium complexes with tethered Hantzsch pyridinium groups: Evidence for direct hydride transfer from dihydropyridine to metal-
activated substrate’, Angew. Chem. Int. Ed., 2013, 52, 3411-3416.
3. A. McSkimming, B. Chan, M. M. Bhadbhade, G. E. Ball, S. B. Colbran, ‘Bio-inspired transition metal–organic hydride
conjugates for catalysis of transfer hydrogenation: Experiment and theory’, Chem. Eur. J., 2015, 21, 2821-2834.
4. B. Das, A. Thapper, S. Ott, S. B. Colbran, ‘Structural features of molecular electrocatalysts in multi-electron redox
processes for renewable energy— recent advances’, Sust. Energy Fuels, 2019, 3, 2159-2175.
5. B. Das, L. Ezzedinloo, M. Bhadbhade, M. P. Bucknall, S. B. Colbran, ‘Strategic design of a ruthenium catalyst for
both CO2 reduction and H2O oxidation: The electronic influence of the co-ligands’, Chem. Comm., 2017, 53, 10006-
10009.
6. T. E. Elton, G. E. Ball, M. Bhadbhade, L. D. Field, S. B. Colbran, ‘Evaluation of Organic Hydride Donors as reagents
for the reduction of carbon dioxide and metal-bound formates’, Organometallics, 2018, 37, 3972-3982.
7. B. Das, J. Chen, K. Ching, M. Bhadbhade, X. Chen, S. B. Colbran, C. Zhao, ‘Immobilized ruthenium complexes as
heterogeneous catalysts for electroreduction of CO2’, ChemCatChem, 2019, MS: cctc.201902020 submitted.
D
68
COORDINATION CHEMISTRY OF THE DIPYRIDYLPYRROLIDE LIGAND
James N. McPherson1, Sally Brooker2, Max Massi3, and Steve Colbran1
1School of Chemistry, UNSW Sydney, Australia 2Department of Chemistry, University of Otago, New Zealand
3School of Molecular and Life Sciences, Curtin University, Australia Email: [email protected]
Metal complexes of the 2,2′:6′,2″-terpyridine (tpy) family of ligands are ubiquitous. 2,5-Di(2-pyridyl)pyrrolide
(dpp–) ligands are wide bite-angle analogues of tpy, and are available by deprotonation of the 2,5-di(2- pyridyl)pyrrole (Hdpp) precursor. We have recently reviewed the literature of tridentate pyridyl-pyrrolide ligands and found that the introduction of a central pyrrolide ring has dramatic electronic and geometric
consequences.1 The steric strain which builds within pincer ligands such as dpp– can be approximated by the
change in terminal N⋯N donor atomic separations, and so is a useful design parameter which can be easily
predicted by DFT methods.2 Although there is a diverse range of Hdpp ligand precursors now available,
including from a simple one-pot protocol,3 the coordination chemistry of these ligands remains underdeveloped. To encourage wider exploration of metal complexes of these overlooked ligands, examples of lanthanide and
transition metal-dpp– will be presented, with interesting redox,4 magnetic4 and photophysical5 properties, or
with useful catalytic reactivities.
A. Prediction of the steric strain which builds within pincer ligands from the change in terminal donor
separation ().2 B. The potential of the reversible CoIII/CoII redox event in [Co(dpp)2] complexes can be predicted from the electronic properties of the pyrrolide substituents. These complexes also displayed gradual
thermal spin crossover in solution and in the solid state.4 C. Emission from Eu(III) and Yb(III) ions in neutral
homoleptic [Ln(dpp)3] complexes is sensitised by the dpp– antennae ligands.5
References
[1] J.N. McPherson, B. Das, S. B. Colbran. Coord. Chem. Rev. 2018, 375, 285.
[2] J. N. McPherson. T. E. Elton, S. B. Colbran. Inorg. Chem. 2018, 57 (19), 12312.
[3] A. McSkimming, S. B. Colbran, et al.. Chem. A Eur. J. 2014, 20 (36), 11445.
[4] J. N. McPherson, R. W. Hogue, F. S. Akogun, L. Bondì, E. T. Luis, J. R. Price, A. L. Garden, S. Brooker,
S. B, Colbran. Inorg. Chem. 2019, 58 (3), 2218.
[5] J. N. McPherson, L. Abad Galan, H. Iranmanesh, M. Massi, S. B. Colbran. Dalt. Trans. 2019, 48 (25), 9365.
69
ORGANIC MIXED-VALENCY ACROSS A FIVE CHARGE STATES OF GROUP 13 COMPLEXES
Amela Arnold1, Tobias J. Sherbow1 and Louise A. Berben2* 1Department of Chemistry. University of California Davis, CA 95616, USA
Email: [email protected]
I will talk about octahedral complexes of Al, Ga, and In(III) that each contain two bis(imino)pyridine (I2P)
ligands and have the form [(I2P)2M]n, where M = Al(III), Ga(III), or In(III), and n spans 3- up to 2+ depending on the charge of each I2P ligand. The charge series can be accessed using cyclic voltammetry or chemically isolated. Analysis of the CV’s and the near infra-red (NIR) and electron paramagnetic resonance (EPR) spectra associated with the octahedral complexes indicates that the mixed-valent members of the charge series,
[(I2P0)(I2P
-)M]2+, [(I2P-)(I2P
2-)M], and [(I2P2-)(I2P
3-)M]2- have completely delocalized electronic structures, where the Al and Ga complexes satisfy the description of Class III mixed-valency and In complexes are Class II/III. Electron delocalization will also be discussed in the context of stabilization of unusual square planar
geometries for Al complexes, and in the context of the chemical reactivity that can be accessed via ligand-based electron and proton transfer reactions.
70
Tuesday 17th
December
Session 2
71
X-RAY METALLOMICS EXAMINES MANGANESE SOD MIMETICS
Hugh H. Harris1*, Claire M. Weekley2 and Ivana Ivanovic-Burmazovic2
1The University of Adelaide, South Australia, Australia 2The University of Melbourne, Victoria, Australia
3Universität Erlangen-Nürnberg, Erlangen, Germany Email: [email protected]
The chemistry of "heavy" elements such as selenium, copper and manganese in biological environments is
fragile, complex and tightly regulated. That chemistry, and the regulation of the elements, is often disturbed in
disease and hence these are important areas of study. X-ray absorption spectroscopy and X-ray fluorescence
imaging are key techniques in our work because, unlike traditional biochemical approaches, they provide
information without the need for significant sample preparation that can perturb the system.
I will discuss the application of X-ray methods to examine the biological chemistry of Mn(II) superoxide
dismutase mimetics,1 which are potential therapeutics for diseases associated with excess superoxide
production, such as inflammatory diseases, ischaemic diseases and cancer. One class of these compounds, the Mn(II) pentaazamacrocycles, are the most active synthetic catalysts of superoxide disproportionation. Some pentaazamacrocycles are also capable of removing NO• and peroxynitrite from cells, but the reaction mechanisms are still under investigation. Until now, little has been known about their speciation or compartmentalisation in cells.
We have used X-ray absorption spectroscopy and X-ray fluorescence imaging methodologies to examine
speciation and distribution in intact cultured cells for these compounds and have attempted to develop protocols
which allow the use of multiple standard fluorescence probes (e.g. mitotrackers) on the same cells prepared for
X-ray fluorescence imaging. This allows correlation of elemental distributions in cells with organelle location,
which can be used to understand the modes of action of metal-based diagnostic and therapeutic agents more
generally.
[1] M.R. Filipović et al., Angew. Chem. Int. Ed. Engl., 2008, 47, 8735-39 and 2010, 49, 4228-32; C. M. Weekley
et al., Inorg Chem., 2017, 56, 6076-6093.
72
TOWARDS IMAGING THE PATHOLOGY OF ALZHEIMER’S DISEASE WITH RADIOACTIVE ISOTOPES OF
COPPER
Lachlan E. McInnes and Paul S. Donnelly.
School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia.
Email: [email protected]
Figure 1. Bright-field imaging (A-B), and Laser-Ablation Inductively-Coupled-Plasma Mass- Spectrometry of human brain tissue (C) labelled with [65Cu][CuL1] (D-E) and an ORTEP representation of [CuL1].
The complex pathology of Alzheimer’s Disease (AD) includes the presence of extracellular amyloid
plaques consisting mostly of the aggregated amyloid-β (Aβ) peptide. While it is long assumed that Aβ deposition
plays an important role in the progression of the disease, its true function in neurodegeneration remains
inconclusive. The advent of radioactive fluorinated imaging agents that bind to amyloid deposits in the brain by
using positron emission tomography (PET). This has allowed further insight into this mechanism and has
allowed the visualisation of amyloid deposition as the disease progresses in living patients. It has also provided
clinicians with a valuable tool to assist in the diagnosis of AD.
While radio-fluorinated imaging agents have led the field in AD imaging, positron-emitting isotopes of
copper (62Cu t1/2 = 10 min, 64Cu t1/2 = 12.7 h) offer an attractive alternative due to their ability to coordinate appropriately designed ligands quickly, and under facile conditions. A positron-emitting copper complex that can accurately measure the plaque burden in the brain may allow for a ‘kit-based’ approach to be applied to AD
imaging, thus negating the need for specialised radiochemistry facilities.1 To this end we have investigated a series of hybrid thiosemicarbazonato-pyridylhydrazone ligands that feature an integrated amyloid targeting
group based on the benzofuranyl motif found in the potential amyloid imaging agent [18F]NAV4694.
Preliminary investigation of this series revealed a versatile ligand framework whose properties can be
modulated via subtle changes on the periphery of the ligand backbone. This includes being able to modulate their blood-brain barrier permeability as well as their metabolic stability as measured in liver microsomes.
Additionally, this class of ligand can be labelled in high radiochemical purity with 64Cu under benign conditions
that could be directly transferable to a kit-based formulation.2
1. L. E. McInnes, S. E., Rudd, P. S. Donnelly, Coord. Chem. Rev., 2017, 352, 499
2. L. E. McInnes, A. Noor, K. Kysenius, C. Cullinane, P. Roselt, C. A. McLean, F. C. K. Chiu, A. K. Powell,
P. J. Crouch, J. M. White, P. S. Donnelly, Inorg. Chem., 2019, 58, 3382
E
O2
N5 N6
N4 O1
Cu
N3
N2
S
N1
73
THE TRANSFERRIN CYCLE: INSIGHTS INTO IRON METABOLISM AND TRANSPORT OF
MEDICINAL AND TOXIC METAL IONS
A. Levina1* and P. A. Lay1,2
1School of Chemistry and 2Sydney Analytical, The University of Sydney, Sydney 2006, NSW, Australia Emails: [email protected], [email protected]
The transferrin (Tf) cycle for Fe(III) transport from blood plasma into cells (see Figure) is of great interest both
as an essential part of mammalian Fe metabolism and as a classical example of protein uptake by cells via
receptor-mediated endocytosis. We have developed the first complete model of Tf cycle in a cell-free system,
using bio-layer interferometry (BLI) [1-3]. This model was used to uncover previously unknown details of the
Tf cycle, particularly the role of blood plasma citrate and ascorbate in Fe(III) release from Tf adduct with
transferrin receptor (TfR1) under acidic endosomal conditions (pH 5.6, Figure a) [3].
We are particularly interested in the controversial role of Tf in cellular uptake of medicinal and toxic metal ions.
Generally, although Tf is capable of binding many metal ions, apart from Fe(III), with high affinity, the resultant
metal-Tf complexes are unable to complete the Tf cycle and are excluded from cells. For instance, the Ru(III)-
Tf complex does not bind to TfR1 with sufficient affinity to enter cells via an endosomal pathway (Figure b)
[1], and the Cr(III)-Tf complex does not release the metal under endosomal conditions, which leads to disruption
of the Tf cycle (Figure c) [2]. Unpublished results for the effects of V(V/IV/III), Mn(III), Ga(III) and In(III) on
Tf cycle will also be presented.
References
[1] A. Levina, P. A. Lay. Inorg. Chem. Front. 2014, 1, 44.
[2] A. Levina, T. H. N. Pham, P. A. Lay. Angew. Chem. Int. Ed. 2016, 55, 8104.
[3] A. Levina, P. A. Lay. ACS Chem. Biol. 2019, 14, 893.
74
NMR STUDIES PROBING INTERACTION OF POLYNUCLEAR PLATINUM COMPLEXES WITH CELL SURFACE
GLYCOSAMINOGLYCANS (GAGS)
Anil K. Gorle1*, Premraj Rajaratnam1, Chih-Wei Chang1, Thomas Haselhorst,1 Mark von Itzstein,1
Susan J. Berners-Price,1 Nicholas P. Farrell,1,2
1Institute for Glycomics, Griffith University, Gold Coast Campus, Australia 2Department of Chemistry, Virginia Commonwealth University, Richmond 23221, USA
Email: [email protected]
Glycosaminoglycans (GAGs) such as heparin and heparan sulfate (HS) bind to wide variety of proteins on the cell surface and exercise important physiological functions such as cell-cell and cell-extracellular matrix
adhesion, and are receptors for adhesion molecules and growth factors.1 Cleavage of GAGs by the enzyme heparanase modulates the tumor-related events including angiogenesis, cell invasion, metastasis and
inflammation.2 Polynuclear platinum complexes (PPCs) capable of binding with carbohydrate fragments through electrostatic and covalent interactions were shown to effectively inhibit the physiologically critical HS functions such as growth factor recognition and the activity of human (heparanase) and bacterial (heparinase)
enzymes on HS.3,4 GAGs act as very efficient receptors for the cellular internalization of PPCs, a unique mechanism not shared by neutral anticancer drugs cisplatin or oxaliplatin. This presentation will focus on the
[1H,15N] HSQC NMR studies that have investigated the mechanism of interaction and covalent binding kinetics of the clinically relevant trinuclear platinum compound, Triplatin, with monosaccharide HS fragments containing variable sulfate substitution. The influence of positive charge distribution in non-covalent PPC analogs on the HS metalloshielding against enzymatic cleavage and 2D NMR and DFT modelling studies to determine solution state structure of the pentasaccharide Fondaparinux, in the presence and absence of a trinuclear non-covalent PPC, TriplatinNC, will also be discussed.
Fig.1. Possible mechanisms of anti-angiogenesis. PPC binding to HS GAGs blocks growth factor recognition and heparanase activity.
References:
1. Neha S. Gandhi and Ricardo L. Mancera. Chem. Biol, Drug Des. 2008, 72, 455-482.
2. Claudio Pisano, Israel Vlodavsky, Neta Ilan, Franco Zunino. Biochem. Pharmacol. 2014, 89, 12-19.
3. John B. Mangrum, Brigitte J. Engelmann, Erica J. Peterson, John J. Ryan, Susan J. Berners-Price and Nicholas P. Farrell. Chem. Commun. 2014, 50, 4056-4058.
4. Erica J. Peterson, A. Gerard Daniel, Samantha J. Katner, Lisa Bohlmann, Chih-Wei Chang, Anna Bezos,
Christopher R. Parish, Mark von Itzstein, Susan J. Berners-Price, Nicholas P. Farrell. Chem. Sci. 2017, 8, 241-252.
75
VISUALISING BIOMATERIAL DEGRADATION WITH LUMINESCENT METALS
Sally E Plush1*
1School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, South Australia.
Email: [email protected].
A gruesome “Hollywood” depiction of a fungal invader that digests its host from inside out
surprisingly has a scientific basis in human biology. Pathogenic yeasts are ubiquitous as
commensal human flora and our body constantly fends off invasion with a healthy skin barrier and
immune system. However, when given an opportunity to access internal tissues, normally benign
yeast microbes utilize sophisticated tissue invasion strategies including sending out digestive
hyphae to break-down human cells and burrow into deep tissues. Unsurprisingly, implanted
devices such as urinary and vascular catheters (used in the millions of units per year in Australia)
easily pick up environmental yeasts and bacteria, and commonly develop into biofilm infections
on these devices. Once tissue invasion reaches the bloodstream, blood sepsis results; for
example in the case of Candida albicans a dire condition known as candidiasis results, which is
associated with a shockingly high mortality rate of 50%. Surprisingly, little is known how to best
combat invasive microbial diseases on surfaces of biomedical devices and implants. The study
of fungi colonization of materials though is very difficult due to the high autofluorescence exhibited
by fungi.
Long lived luminescent metal ion complexes offer advantages for the study of colonization as they
offer extended resistance to fluorophore destruction, large Stokes’ shifts (large separation
between absorption and emission wavelengths) that avoid concentration-dependent self-
absorption problems, long luminescence lifetimes (range 1 µs to 5 ms) that enable time gated
measurement of luminescence, avoiding either background or specific auto-fluorescence.1-3 In
this presentation luminescent metal complexes will be used to study the degradation of both
biodegradable and nonbiodegradable materials by fungi.4
References
1Louie, M.-W.; Liu, H.-W.; Lam, M. H.-C.; Lau, T.-C.; Lo, K. K.-W. Organometallics 2009, 28,
4297.2Thorp-Greenwood, F. L.; Balasingham, R. G.; Coogan, M. P. Journal of Organometallic
Chemistry 2012, 714, 12. 3Fernández-Moreira, V.; Thorp-Greenwood, F. L.; Coogan, M. P.
Chemical communications 2010, 46, 186. 4Coad, B; Michl, T. D.; Bader, C. A.; Baranger, J.; Giles
C.; Goncalves G. C.; Nath P.; Lamont-Friedrich S. J.; Johnsson M.; Griesser H. J.; Plush S. E.;
ACS Appl. Bio. Mater 2019, accepted DOI.org/10.1021/acsabm.9b00520
76
6
6
ANION BINDING IN MIXED LIGAND M2L4 QUADRUPLE HELICATES
Casey S. Bardsley and David A. McMorran* Department of Chemistry Te Tari Hua Ruānuku, University of Otago, Dunedin, New Zealand
Email: [email protected]
19F NMR spectrum of a 2:2:2 ‘Pd(BF4)2’:L1:L2 mixture in dmso-d6, showing the BF4- resonances
The first example of an M2L4 quadruple helical cage ([PF -@Pd2L14]3+) was reported in 1998. Notably, the
cavity generated by the four L1 ligands and the two palladium(II) cations was found to contain one of the PF -
counterions.1 It was subsequently shown by solution NMR studies that this anion could be exchanged by other anions and X-ray crystal structures both highlighted the compact nature of these helicates and also showed that
the helicate can adapt its size in response to the size of the encapsulated anion.2
Since this initial report a number of groups have explored the synthesis and host-guest chemistries of these
systems3 and recently, reports of cages with more than one type of ligand have appeared.4 We have also been
interested in forming such mixed-ligand cages. Given the compact nature of the [Pd2L14]3+ helicate, we are
exploring the synthesis of cages containing both L1 and the related ligand L2, where the central phenyl ring has been replaced by a much larger anthracenyl unit - we imagine that the steric bulk of L2 will limit the possible
mixed-ligand helicates that can form. To date we have looked to use HR ESIMS, 19F DOSY and DFT
calculations to characterise the libraries of [Pd2L1xL24-x]3+) cages that form and we also have begun to look at
anion exchange experiments in these libraries. We hope that the differences in the structures of the different mixed ligand helicates will lead to differences in anion binding/selectivity and so shed further light on the source
of the selectivity of the [Pd2L14]3+ helicate.
1. D. A. McMorran and P. J. Steel, Angew. Chem. Int. Ed., 1998, 37, 3295.
2. P. J. Steel and D. A. McMorran, Chem. Asian J., 2019, 14, 1098.
3. A. Schmidt, A. Casini and F. E. Kühn, Coord. Chem. Rev., 2014, 275, 19. M. Han, D. M. Engelhard,
G. H. Clever, Chem. Soc. Rev., 2014, 43, 1848.
4. S. Pullen and G. H. Clever, Acc. Chem. Res., 2018, 51, 3052.
77
DIASTEREOSELECTIVE CONTROL OF TETRAPHENYLETHENE REACTIVITY BY METAL TEMPLATE SELF- ASSEMBLY
Aaron D. W. Kennedy* and Jon Beves School of Chemistry, UNSW Sydney, Australia.
Email: [email protected]
I will present the development of a “supramolecular protecting group” strategy to control reactivity of an organic molecule. The reaction of an amine substituted tetraphenylethene with 2-pyridinecarboxaldehyde and iron(II)
salts resulted, after aqueous workup, in the diastereoselective formation of a [Fe2L3]4+ triple-stranded helicate
structure. This structure was isolated irrespective of the stoichiometry employed. The use of Fe(II)(BF4)2 or
Fe(II)(NTf2)2 as the iron source allowed the formation of a [Fe8L6]16+ cube when appropriate stoichiometry was
used, but these structures are unstable with respect to hydrolysis. The pendant amine groups on the helicate are suitable for post-assembly modification with acid chlorides or acid anhydrides and the resulting non- symmetrically functionalized tetraphenylethene (TPE) units were isolated and their emissive properties studied.
References
1 A. D. W. Kennedy, N. de Haas, H. Iranmanesh, E. T. Luis, C. Shen, P. Wang, J. R. Price, W. A. Donald, J
Andréasson, F. Huang, and J. E. Beves, Chem. Eur. J., 2019, 25, 5708-5718.
78
DECTRIS EIGER DETECTORS AT THE ANSTO MX BEAMLINES – DYNAMIC CO-ORDINATION COMPLEXES
Jason R. Price1* 1, ANSTO – Melbourne, Australian Synchrotron, Clayton, VIC Australia
Email: [email protected]
The Australian Synchrotron MX beamlines support a user community that includes both Structural Biology
(PX) and Chemical Crystallography (CX). Addressing the needs of both communities leads to a number of
compromises regarding the design and implementation of the beamline infrastructure; however, it also leads to
unique opportunities. Both MX Beamlines have recently had detector upgrades:
- MX2 received a Dectris Eiger 16M with the financial assistance of both the Australian Cancer
Research Foundation and the PX user community in Jan 2017
- MX1 commissioned a Dectris Eiger 2 9M in May 2019 as part of the Australian Synchrotron capital
upgrades.
These single photon counting detectors replace the previous CCD Area detectors, with the improvement
in technology allowing an increase in frame rates from one second a frame to >0.01 seconds a frame. A full data
collection given in the figure was completed in one second.
The reduction in data acquisition time allows full collections for CX data to be complete in seconds
(rather than minutes). There are a number of single crystals systems that undergo dynamic changes, the detector
upgrades enable investigation of these dynamic systems in ‘real time’, allowing snapshots of the changes to be
captured and resulting in a more thorough understanding than was previously possible. Flexible crystals can be
bent in situ and diffraction datasets can be collected at specific points along the crystal with the micro focus
beamline MX2. The resulting structures can be compared based on where the x-rays hit the crystal i.e. on the
inside of the bend through to the outside.1
Crystals that undergo phase transitions, e.g., spin crossover compounds, or have another gradient of
change (flexibility) can now rapidly be examined as full crystal structure over the range of their transition. Given
the opportunity to collect enormous amounts of single crystal data, the automation of collection, data reduction,
structure refinement, and validation will be discussed.
1 A. Worthy, A. Grosjean, M. C. Pfrunder, Y. Xu, G. Edwards, J. Clegg, J. C. McMurtrie. Nature
Chemistry. 2018, 10, 65.
79
SIZE-SELECTIVE HYDROFORMYLATION BY A RHODIUM CATALYST CONFINED IN A SUPRAMOLECULAR CAGE
Sandra S. Nurttila1,2*, Wolfgang Brenner3, Jesús Mosquera3, Kaj M. van Vliet1, Jonathan R.
Nitschke3 and Joost N. H. Reek1
1Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, the Netherlands 2Current institute: CBNS, University of New South Wales, NSW, Australia
3Department of Chemistry, University of Cambridge, Cambridge, United Kingdom Email: [email protected]
Confinement of the catalytically active site is the key reason for high activities and selectivities observed in enzymatic transformations. The intrinsic complexity of natural enzymes has urged chemists to study simpler
supramolecular cage analogues1 to ultimately achieve higher activity and selectivity in known catalytic
transformations. Selective encapsulation of catalysts in cages, which should remain throughout the catalytic
cycle in competition with substrate molecules, is challenging.2 One strategy involves the use of ligand templates,
i.e. building blocks that can coordinate to the active metal center and simultaneously to the building blocks that
form the cage.3
Here we demonstrate a new example of cage-controlled catalysis, namely size-selective hydroformylation of a
series of aliphatic and aromatic alkenes.4 The encapsulation of the catalytically active complex within the
[M4L6]8+ capsule is coordination-driven, relying on the supramolecular pyridine-zinc porphyrin interaction.
DFT calculations confirm that the second coordination sphere forces the encapsulated active species to adopt
the ee coordination geometry (i.e., both phosphine ligands in equatorial positions), in line with in situ high-
pressure IR studies of the host–guest complex. The window aperture of the cage decreases slightly upon binding
the catalyst. As a result, the diffusion of larger substrates into the cage is slower compared to that of smaller
substrates. Consequently, the encapsulated rhodium catalyst displays substrate selectivity, converting smaller
substrates faster to the corresponding aldehydes. Moreover, an interesting odd-even effect is observed in the
conversion of alkenes of different chain length, where even-numbered alkenes display higher conversions than
odd-numbered ones. This selectivity bears a resemblance to an effect observed in nature, where enzymes are
able to discriminate between substrates based on shape and size by embedding the active site deep inside the
hydrophobic pocket of a bulky protein structure. In this talk the highlights of this published work will be
presented.
[1] D. M. Wood, W. Meng, T. K. Ronson, A. R. Stefankiewicz, J. K. M. Sanders, J. R. Nitschke, Angew.
Chem. Int. Ed. 2015, 54, 3988.
[2] S. H. A. M. Leenders, R. Gramage-Doria, B. de Bruin, J. N. H. Reek, Chem. Soc. Rev. 2015, 44, 433.
[3] V. F. Slagt, J. N. H. Reek, P. C. J. Kamer, P. W. N. M. van Leeuwen, Angew. Chem. Int. Ed. 2001, 40,
4401.
[4] S. S. Nurttila, W. Brenner, J. Mosquera, K. M. van Vliet, J. R. Nitschke, J. N. H. Reek, Chem. Eur. J.
2019, 25, 609.
80
SUPRAMOLACULAR.ORG – LATEST DEVELOPMENTS: 1:3 BINDING AND A CASE STUDY ON A NICKEL(II) MORPHOLINE PHOTOCATALYTICAL COMPLEX
Varvara Efremova1, James Wilmot, Max Kudisch,2 Chern-Hooi Lim2, Garret M. Miyaki and Pall
Thordarson1* 1School of Chemistry, Australian Centre for Nanomedicine and the ARC Centre of Excellence in Converged
Bio-Nano Science and Technology, The University of New South Wales, Sydney, NSW, Australia 2Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
2 New Iridium LLC, Boulder, Colorado 80303, United States
Email: [email protected]
Following our work towards a more robust methodological framework for determining binding constants in
supramolecular chemistry,1,2 we launched in 2015 a web-portral supramolecular.org3 that allows end-users to
freely use verifiable binding models and save all their results with a permanent identifier (url) in a F.A.I.R.4
(fair, accessible, interoperable and re-usable) manner. We will here outline our experience in running this service which has had over 30,000 users to date and over 100 citations in the literature. We will also outline
coming extensions and improvement to the supramolecular.org website which include the capability of fitting higher order equilibria such as the 1:3 complex formation as exemplified in our recent work on the mechanism of a nickel(II)-triamine complex that plays a crucial role in a novel dual catalytic, light-driven C-N cross
coupling reaction system.5
1. P. Thordarson. Chem. Soc. Rev. 2011, 56, 12224.
2. B. D. Hibbert, P. Thordarson. Chem. Commun. 2016, 56, 12224.
3. http://supramolecular.org
4. M. D. Wilkingson et al, Scientific Data 2016, 3, 160018. 5. M. Kudisch, C.-H. Lim, P. Thordarson, G. M. Miyake. J. Am. Chem. Soc. 2019 (ja-2019-11049m) under final
review (30 Oct 2019).
81
POLYSILANES: THE UNABRIDGED VERSION
KRISTEL M. RABANZO-CASTILLO1,2, VIPIN B. KUMAR 1,2, AND ERIN M LEITAO1,2* 1The School of Chemical Sciences, University of Auckland, Auckland, New Zealand
2The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand Email: [email protected]
Synthetic polymers have revolutionized our existence. The range of accessible consumer materials
(e.g. packaging, electronics, toys, tyres, textiles, etc.), structural materials, and biomaterials has grown dramatically over the past century and has a great impact on our daily lives. What is most fascinating
about this diverse range of materials is that the vast majority of these contain exclusively carbon in the backbone. Substituting the carbon atoms with other main-group atoms, such as silicon, nitrogen,
phosphorus, boron, oxygen and sulfur will create materials with modified properties (e.g. strength,
flexibility, conductivity, solubility, etc.) giving rise to exciting new applications.1,2 For example, polysilanes, long chains of silicon atoms linked together, are semi-conducting due to the presence of
unique -conjugation along the polymer backbone. Despite being attractive due to their extraordinary
electronic and photo-physical properties3 as well as being available, as the first synthesis was over 100
year ago, polysilanes have yet to become commercial materials.4 Weak Si-Si bonds, moisture sensitive
substituents and poor control over the polymer synthesis are the major obstacles to their widespread use. In our research, we aim to address these issues through the preparation of bridged dimers and by
determining new catalytic routes to link the silicon atoms together.
1. E. M. Leitao, T. Jurca, I. Manners Nature Chem. 2013, 5, 817.
2. A. M. Priegert, B. W. Rawe, S. C. Serin, D. P. Gates Chem. Soc. Rev. 2016, 45, 922. 3. S. Seki, S. Tagawa Polym. J. 2007, 39, 277.
4. F. S. Kipping J. Chem. Soc. 1924, 125, 2291.
R weak Si-Si bond
subject to cleavage
reinforcement extra reinforcement potential for
R modification
H
H
H
R
H
R' R R'
R' R' R' R'
catalyst
R
R'
H
H
H
H
- H2
= Si
H
R R'
H R' R'
superior catalyst R R
R' R R R' n H H
- H
2
H H
R' = Si R R
R' X, R' = H, n >7
Y, n < 7
air and
moisture
sensitive
R R H H R' R' n
R R Z, n > 10
current state-of-the-art our research
82
DEVELOPING CARBORANE-SUPPORTED FRUSTRATED LEWIS PAIRS
James D. Watson1, Amanda Benton2 and Alan J. Welch2* 1University of New South Wales, Sydney NSW 2052, Australia
2Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
Email: [email protected]
Carboranes offer a unique tuneability as a scaffold. Substituents bound via the boron (B) vertices experience an overall electron donating effect from the cage and substituents bound via the carbon (C) vertices experience an overall electron withdrawing effect from the cage. The archetypal 12-vertex C2B10H12
icosahedral carborane has three isomers ortho-, meta-, and para-carborane and is renowned for its thermal stability. The stability, electronic versatility and structural diversity of carboranes has been exploited in a myriad of applications, from medicinal chemistry to organic catalysis, but until recently carboranes have not
been applied to the field of Frustrated Lewis Pairs (FLPs).1, 2
The pseudo aromaticity of the carborane cluster coupled with their significant 3D bulk makes carborane the ideal scaffold for FLPs.
We are interested in using carboranyl cages as scaffolds for Lewis acid (LA) and/or Lewis base (LB) units because the extensive variability inherent in these clusters means that, at least in principle, it should be possible to tune the acidity or basicity of the appended LA or LB unit. Control over the acid and/or base strength of Lewis acid/Lewis base components of FLPs is desired for optimisation of the effectivity of FLPs in catalysis. We have recently reported studies of the various factors that affect the basicity of
carboranylphosphines and acidity of borylcarborane.3, 4
An important (yet rather surprising) conclusion from this study was that the strength of the LB or LA fragment is not affected by the electronic influence of the substituents bound via the second C vertex of the cage.
References
[1] R. N. Grimes, Carboranes, 2nd ed., Academic Press, Amsterdam, 2011.
[2] R. N. Grimes, “Icosahedral Carboranes,” in Carboranes, Elsevier, Amsterdam, 2016, 249.
[3] A. Benton, Z. Copeland, S. M. Mansell, G. M. Rosair, and A. J. Welch, Molecules, 2018, 23, 3099.
[4] A. Benton, Derek J. Durand, Zachariah Copeland, James D. Watson, Natalie Fey, Stephen M. Mansell,
Georgina M. Rosair and Alan J. Welch, Inorg. Chem., 2019.
B1
C1
C21
C2
C13
C12 C14
C15
C11 C16
O12 O11
B1
C1
C2
83
2
MIXED-VALENCE MODELS OF MOLECULES THAT OFFER MORE THAN MORE MOORE
Masnun Naher, Daniel R. Harrison and Paul J. Low*
School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009,
Australia
Email: [email protected]
OMe
C C C C
Ru Ru
Ph2P PPh2
Ph P PPh2
The field of molecular electronics has advanced rapidly following the development of convenient laboratory methods for the construction of electrode | molecule | electrode ‘molecular junctions’, and the use of these
devices in the measurement of through-molecule conductance.1
These studies have allowed exploration of the
electrical properties of a wide range of molecular structures, establishing a number of structure property relationships and leading to improved concepts for the design of molecular ‘components’ with high electrical
conductivity, outstanding rectification ratios, and transistor-like gated conductance.2
In addition, uniquely
molecular phenomena that influence the transmission of charge such as quantum interference (QI) have been
identified providing new avenues for molecular design,3
and leading to proposals for the design of molecular materials with useful properties such as an enhanced thermoelectric figure of merit ZT and promisingly high
power factors GS2.4
Such concepts and associated investigations contribute to a growing awareness of the potential for molecular junctions to offer function beyond electron transport.
However, whilst methods of measuring conductance have become more widely available, the technique remains relatively specialised. Alternatively, mixed valence models have a long history of use in modeling
charge transfer processes predating metal|molecule|metal junction measurements.5
Spectral data, in the form of intervalence charge transfer (IVCT) bands, often found in the NIR-IR region, and characteristic IR
spectroscopic markers are easily obtained and can be analysed using a variety of theoretical treatments.6-9
In this presentation we show evidence for the ability to control QI effects in both molecular junctions and
mixed-valence models through the introduction of pendant groups to the periphery of 1,3-diethynyl benzene
based systems. The potential to use spectroelectrochemical methods to rapidly screen target systems for QI as
an aid to the further development of structure-property relationships in molecular electronics will be
discussed.
1. S. Marques-Gonzalez and P. J. Low, Aust J Chem, 2016, 69, 244-253.
2. A. Vilan, D. Aswal and D. Cahen, Chem Rev, 2017, 117, 4248-4286.
3. C. J. Lambert, Chem Soc Rev, 2015, 44, 875-888.
4. H. Sadeghi, S. Sangtarash and C. J. Lambert, Nano Lett, 2015, 15, 7467-7472.
5. J. P. Launay, Coordin Chem Rev, 2013, 257, 1544-1554.
6. S. Guckel, J. B. G. Gluyas, S. El-Tarhuni, A. N. Sobolev, M. W. Whiteley, J.-F. Halet, C. Lapinte, M.
Kaupp and P. J. Low, Organometallics, 2018, 37, 1432-1445.
7. J. B. G. Gluyas, S. Guckel, M. Kaupp and P. J. Low, Chem-Eur J, 2016, 22, 16138-16146.
8. M. Parthey, J. B. G. Gluyas, M. A. Fox, P. J. Low and M. Kaupp, Chem-Eur J, 2014, 20, 6895-6908.
9. M. Parthey, J. B. G. Gluyas, P. A. Schauer, D. S. Yufit, J. A. K. Howard, M. Kaupp and P. J. Low,
Chem-Eur J, 2013, 19, 9780-9784.
84
SODIUM MAGNESIATE FACILITATED CYCLISATION OF IMINES VIA C-F ACTIVATION
Samantha A. Orr, Timothy Wollmann, Phil C. Andrews* and Victoria L. Blair*
Monash University, VIC, Australia
Email: [email protected]
Figure 1: Reaction of pentafluoro-arylimine and sodium-magnesiate mediated C-F activation.
Imines are valuable building blocks for the synthesis of many complex molecules due to their simple
preparation. Applications of Schiff’s bases include ligands for metal-complexation, preparation of amines and
precursors for pharmaceutical scaffolds. Due to their importance, efforts to develop new functionalisation
methods are ongoing. A concurrent interest we have is the synthetic design of fluorinated substrates, owing to
their medicinal relevance with a C-F bond appearing in 20% of new drugs.1
Transition metals have generally
dominated the field of C-F activation2
but more recently s-block and low valent species have showed success.3
The work presented will focus on synthetic transformations of fluoro-substituted imines employing our sodium-
magnesiate bimetallic base and the monometallic counterparts. Initial studies revealed a selective ortho-C-F
activation of a pentafluoro-substituted aryl imine, leading to the unprecedented cyclisation of two imine species
(figure 1). The resultant novel 8-membered carbon-nitrogen ring has been fully characterised by x-ray
crystallography and NMR spectroscopy, the scope has been extended and the mechanistic pathway probed.
References
[1] K. Müller, C. Faeh, F. Diederich, Science, 2007, 317, 1881. [2] T. Fujita, K. Fuchibe, J. Ichikawa, Angew.
Chem. Int. Ed., 2019, 58, 390. [3] F. M. García-Valle, V. Tabernero, T. Cuenca, M. E. G. Mosquera, J. Cano,
Organometallics, 2019, 38, 894; C. Bakewell, A. J. P. White, M. R. Crimmin, J. Am. Chem. Soc., 2016, 138,
12763.
85
INTRAMOLECULAR EXCHANGE IN RHENIUM ALKANE COMPLEXES: AN NMR STUDY
Mushi He and Graham E Ball* School of Chemistry, UNSW Sydney, NSW 2052, Australia
Email: [email protected]
1 H [M]
C H H
2 H [M]
C H
CH3
1,4 shift
5
[M] H
H C
H
3 H [M]
C H
1,2 shift
4
[M] H
H C
H3C
Transition-metal alkane complexes are of significant interest because of their role as short-lived intermediates
in C-H activation reactions and because they are held together by weak agostic interactions.
We have previously reported observing three isomers of iPrCpRe(CO)2(pentane) using NMR spectroscopy,
wherein the pentane can bind through C1, C2 or C3 of the pentane ligand.1
The three isomers of iPrCpRe(CO)2(pentane) are related by intramolecular exchanges which include 1,2 shifts, 1,3 shifts, 1,4 shifts and 1,5 shifts as shown in the figure above. These processes have the appearance of the metal ‘walking’ along the linear pentane chain. In this project, we have used 2D NMR spectroscopy to look for each of these shifts that can interconvert the three isomers of iPrCpRe(CO)2(pentane) and the results will be presented. In turn, this has allowed us to experimentally test the theoretical predictions of which of these
processes will be the fastest.2
1. D. J. Lawes, S. Geftakis, G. E. Ball. J. Am. Chem. Soc. 2005, 127, 4134.
2. M. Thenraj, A. G. Samuelson. J. Comput. Chem., 2015, 36, 1818.
86
CRYO ATOM PROBE – MEASURING HYDROGEN IN STEELS VIA DEUTERIUM CHARGING.
Julie M. Cairney1*, Ingrid McCarroll
1, Yi-Sheng Chen
1 and Takanori Sato
1
1The Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW, Australia
Email: [email protected]
Hydrogen in steel is associated with a catastrophic failure mode, known as hydrogen embrittlement. This phenomenon is abrupt and is initiated at the atomic level. Although the exact mechanisms are still subject to
debate,1
some mitigation strategies are available, including minimizing hydrogen ingress with surface coatings, or controlling hydrogen diffusion within via the introduction of microstructural ‘traps’, e.g. second
phase precipitates such as niobium carbide.2
It is believed that the incorporation of fine, distributed traps can reduce the mobility of detrimental hydrogen atoms and mitigate the macroscale embrittlement. However, as
hydrogen is difficult to examine at fine scale, the experimental evidence is lacking for further optimization of
the microstructural design.
Atom probe tomography is a powerful technique that can provide accurate 3D maps showing the position and identity of atoms. H is easily detected but, because it is so mobile, researchers are never sure whether it arises
from the sample or the chamber itself. It has recently been demonstrated3
that this issue can be tackled by
charging samples with deuterium (D), the less common stable isotope of H, and cooling the specimen to
cryogenic temperatures immediately after charging to slow diffusion. This approach allows the D to serve as a
marker for H, so that the location of the H atoms can be determined unambiguously.
The University of Sydney has recently installed a suite of tools that allow the preparation and transfer of
samples into and between instruments via ultra-high vacuum cryogenic transfer. These facilities include a
purpose-built controlled-atmosphere glovebox (Microscopy Solutions), a Zeiss Auriga scanning electron
microscope-focused ion beam (SEM-FIB) equipped with a custom-designed cryogenic stage (also Microscopy
Solutions), and a CAMECA laser-assisted local electrode atom probe (LEAP) equipped with a Vacuum and
Cryo Transfer Module (VCTM) on the load lock, all which are connected by a Ferrovac UHV suitcase.
This new specimen treatment chamber allows specimens to be charged with D in a gaseous environment, at
various temperatures, quenched to cryogenic conditions and then transferred to the atom probe for analysis.
This talk will include an overview of this system as well as atom probe data from deuterated steel samples,
including direct observation of deuterium at trapping sites, such as dislocations, grain boundaries and
precipitates in martensitic steels.
References
1. I. M. Robertson, P. Sofronis, A. Nagao, M. L. Martin, S. Wang, D. W. Gross, K. E. Nygren. Metall Mater
Trans A. 2015, 46a, 2323-2341
2. H. K. D. H. Bhadeshia. ISIJ International. 2016, 56, 24-36
3. Y.S. Chen, D. Haley, S. S. A. Gerstl, A. J. London, F. Sweeney, R. A. Wepf, W. M. Rainforth, P. A. J.
Bogot, M. P. Moody. Science. 2017. 355, 1196-1199.
87
UNDERSTANDING EXCHANGE INTERACTIONS VIA ORGANIC LIGANDS: AN INELASTIC NEUTRON
SCATTERING STUDY OF NI3(OH)2(C4O4)2.3H2O
Richard A. Mole1*, Norman Booth1, Kirrily C. Rule1 and Dehong Yu1
1Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
Email: [email protected]
The study of magnetic coordination polymers often relies on the premise that magnetic exchange
coupling via organic ligands is weak. In many cases this is clearly a simplistic assumption as
transitions to long range magnetic order are observed. Determining the strength and nature of such
interactions mediated via ligands is a challenging topic.
We have been studying the porous coordination polymer Ni3(OH)2(C4O4).3H2O and its deuterated
analogue. This complex has an unusual magnetic phase diagram whereby there is a complex
interplay of ferro and antiferromagnetism. To attempt to understand this we have conducted an
inelastic neutron scattering experiment and analysed the observed signal using linear spin wave
theory. This has allowed us to parameterise the microscopic Hamiltonian and determine the strength
of the exchange interactions that are mediated via the squarate ligand. What is surprising in this case
is that these long range interactions are comparable to the strength of one of those exchange
interactions mediated via a one atom hydroxide bridge.
88
Where the simple things in life seldom are: Studies of some AMO4 scheelites.
Brendan J. Kennedy1 and Sean Injac 1
1The University of Sydney, Sydney, NSW, Australia Email: [email protected]
<Figure>
The vast majority of solid state oxides contain transition metals in an octahedral, or a distorted variant thereof, environment and the interconnectivity and distortions of the MO6 units
drive their interesting and occasionally technologically important physical properties. Oxides where the transition metal has a tetrahedral geometry are less well studied. The Scheelite structure is one
such example and this presentation will describe some of our recent studies on two classes of
scheelites; the 3:5 oxides Ln3+Nb5+O4 and the 1:7 oxides A1+M7+O4 (A = Ka, Rb, Cs, Tl; M = Tc, Ru, Re and Os).
The synthesis, structures and magnetic properties of the Ru and Os salts AMO4 (A = K, Rb
and Os) are described. Both K salts adopt the ideal tetragonal Scheelite structure and contain
isolated MO4 tetrahedra. Both show AFM ordering along [001] described by k = 000 at low temperature and neutron diffraction measurements reveal a reduced moment ~ 0.5 μβ due to a
combination of covalency and spin-orbit coupling. RbOsO4 displays the same tetragonal structure
and is an antiferromagnet with TN ~ 20K. RbOsO4 has an orthorhombic structure in Pnma as a consequence of rotations of the OsO4 and this transforms to the tetragonal structure upon heating
above 400 K; both Rb salts are AFM. At room temperature the two Cs salts are both orthorhombic and both undergo additional transitions upon cooling.
Temperature dependent structural studies of ATcO4 (A = Ag, Tl, Rb and Cs) from 90K to
their melting points reveal unexpected phase transitions in RbTcO4 that displays a I41/a to I41/amd
transition and in TlTcO4 where the orthorhombic (Pnma) to tetragonal (I41/a) transformation
proceeds via an intermediate orthorhombic phase. Like the Ru and Os oxides CsTcO4 undergoes a first order orthorhombic (Pnma) to tetragonal (I41/a) transition upon heating.
In the corresponding lanthanoid orthoniobates, LnNbO4 we find that at room temperature it is
best to describe the Nb as in a highly distorted six-coordinate geometry with two long, ~ 2.5 Å, and
four short ~ 1.9 Å Nb-O distances rather than a distorted tetrahedral environment. Variable
temperature structural studies of three examples, Ln = La, Sm and Gd, showed each transformed to a
high temperature tetragonal scheelite type structure in space group I41/a where the Nb cation are
tetrahedrally coordinated and it appears that monoclinic – tetragonal transition is best described as a
reconstructive transition in which the long Nb-O(1) bond is broken upon heating.
89
ELECTROMECHANICAL COUPLING IN DIPOLAR MOLECULAR COMPOUNDS
Y Liu
Research School of Chemistry, the Australian National University, ACT 2601, Australia Email:[email protected]
Dipolar molecular crystals present different physical properties from traditionally strongly correlated ionic
solid-state inorganic crystals due to the weak intermolecular bonding. Herein, centrosymmetric dipolar
molecular crystals of the organoruthenium complex trans-[Ru(C[triple bond, length as m-dash]CC6H4-4-
NO2)(C[triple bond, length as m-dash]CPh)(dppe)2] [dppe = 1,2-bis(diphenylphosphino)ethane] display a large
electric-field-induced strain behaving differently from conventional piezoelectric materials that must,
structurally, be noncentrosymmetric. Further studies of related systematically varied crystalline
organoruthenium complexes reveal that the strong electromechanical coupling effect is not from classical
ferroelectricity, electrostriction, flexoelectricity or electrochemical strain. It is, instead, attributed to the disorder
in the molecular packing, which facilitates reorientation of the molecular dipoles under the action of an applied
electric field. This provides a fresh insight into the design and development of new functional materials and a
promising source of electromechanical coupling in organometallic, and more generally dipolar molecular,
crystals.
90
Don Stranks
Awards Session
91
EXPLORING THE BIOLOGICAL ACTIVITY AND PHOTOINDUCED CO-RELEASE
OF BISMUTH(III) FLAVONOLATE COMPLEXES
Kirralee J. Burke1*, Liam J. Stephens, Melissa V. Werret1 and Philip C. Andrews1
1School of Chemistry, Monash University, VIC, Australia Email: [email protected]
There is increasing interest in the development of metallodrugs to combat the emergence of drug-resistant
bacteria and for use as anticancer agents.[1-2] Metal-flavonolate complexes have been explored for potential
therapeutic utility in these areas, however their development has been relatively limited to complexes derived
from transition metals, such as Ru(II).[3] The pharmacological properties of bismuth have been known for
centuries, and bismuth-containing drugs bismuth subsalicylate (BSS) and bismuth subcitrate (CBS) remain in
clinical use.[4] Motivated by recent reports on the potential therapeutic applications of metal-flavonolate
complexes, we have synthesised a series of homoleptic [Bi(flav)3] and heteroleptic [BiPh(flav)2] bismuth(III)-
flavonolate complexes. The biological activity of the complexes towards bacterial and mammalian cells has
been assessed.
The bioactivity of the compounds is influenced by the degree of substitution of both the bismuth centre and the
respective flavonolate ligands. The heteroleptic bismuth-flavonolate compounds were found to be active
towards problematic Gram-positive and Gram-negative bacteria such as methicillin-resistant Staphylococcus
aureus (MRSA), vancomycin-resistant Enterococci (VRE), and E. Coli. These compounds also reduced
mammalian cell viability in a dose-dependent manner. The homoleptic analogues only inhibited growth of
Gram-positive bacteria and remained relatively non-toxic towards mammalian cells. This structure-activity
relationship has been observed with bismuth complexes derived from other ligand classes,[5-6] and will be
discussed with particular reference to the cellular Bi uptake.
When exposed to visible light under aerobic conditions, the flavonolate ligands of the bismuth complexes
undergo a photoinduced cleavage and concomitant CO-release (Figure 1), and the resulting bismuth-carboxylate
complexes can be isolated from the reaction solution. Studies of this reactivity will be presented and discussed.
Figure 1 – Notable properties of heteroleptic bismuth(III)-flavonolate complexes
[1] S. Komeda, A Casini. Curr. Top. Med. Chem. 2012, 12, 219.
[2] M. A. Sierra, L. Casarrubios, M. C. del lar Torre. Chem. Eur. J. 2019, 25, 7273.
[3] S. Movassaghi, E. Leung, M. Hanif, B. Y. T. Lee, H. U. Holtkamp, J. K. Y. Tu, T. Sohnel, S. M. F. Jamieson, C.
G. Hartinger. Inorg. Chem. 2018, 57, 8521.
[4] G. G. Briand, N. Burford. Chem. Rev. 1999, 99, 2601.
[5] A. Luqman, V. L. Blair, R. Brammananth, P. K. Crellin, R. L. Coppel, P. C. Andrews. Chem. Eur. J. 2014, 20,
14362.
[6] M. Werrett, M. Herdman, R. Brammananth, U. Garusinghe, W. Batchelor, P. Crellin, R. Coppel, P. Andrews.
Chem. Eur. J. 2018, 24, 12938-12949.
92
INVESTIGATIONS OF MIXED-VALENCY AND INTERVALENCE CHARGE TRANSFER IN METAL-ORGANIC
FRAMEWORKS
Patrick W. Doheny1*, Cameron J. Kepert1 and Deanna M. D’Alessandro1
1The University of Sydney, Sydney, NSW, Australia, 2006
Email: [email protected]
Figure 1. a) Crystal structure of the [Cd(BPPTzTz)(tdc)]n·2DMF framework showing the cofacial BPPTzTz
ligands and b) in situ UV-Vis-NIR spectroelectrochemistry showing the appearance of IVCT bands upon
electrochemical reduction.
Metal-organic frameworks (MOFs) are a promising class of materials into which multifunctional properties can
be engineered in a concerted and controlled manner. One active field of research in this area is the synthesis of
electroactive and conductive materials for applications including electrochromic devices (e.g., ‘smart
windows’), energy storage, porous conductors and electrocatalysis, amongst others.1 The application of
conductive MOFs is impeded by several factors, the most significant being the insulating nature of the discrete
components that often constitute the materials, and their instability to the structural changes induced by redox
processes.
This presentation will describe a series of new frameworks developed in our laboratory that display unusual
electronic properties that have been linked to a mixed-valence state of the materials.2,3 A two-fold
interpenetrated Cd2+ MOF incorporating the redox-active ligand 2,5-bis(4-(pyridin-4-yl)phenyl)thiazolo[5,4-
d]thiazole (BPPTzTz) and its functionalised derivatives was synthesised and its electronic behaviour
characterised using solid state electrochemical and in situ spectroelectrochemical (SEC) techniques. An
isostructural Zn2+ framework incorporating the electroactive ligand 2,5-bis(3-fluoro-4-(pyridin-4-
yl)phenyl)thiazolo[5,4-d]thiazole (BPPFTZTz) was also synthesised and investigated using ex situ
techniques to access novel mixed-valence properties. The origin of the optical Intervalence Charge Transfer
(IVCT) bands upon in situ electrochemical and ex situ chemical reduction was elucidated using a combined
experimental, theoretical and computational approach with both Density Function Theory (DFT) and Time-
Dependent Density Functional Theory (TD-DFT) playing a key role in identifying the underlying charge
transfer mechanism.
References
1. D. M. D'Alessandro. Chem. Comm. 2016, 52, 8957.
2. C. Hua, P. W. Doheny, B. Ding, B. Chan, M. Yu, C. J. Kepert, D. M. D’Alessandro. J. Am. Chem. Soc.
2018, 140, 6622.
3. B. Ding, C. Hua, C. J. Kepert, D. M. D'Alessandro. Chem. Sci. 2019, 10, 1392.
93
EVALUATION OF OXORHENIUM(V) AND OXOTECHNETIUM(V) COMPLEXES FOR THE DIAGNOSIS OF
ALZHEIMER’S DISEASE
Benjamin Spyrou1*, Michelle T. Ma2 and Paul S. Donnelly1
1School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
2School of Biomedical Engineering and Imaging Sciences, King’s College London, St. Thomas’ Hospital, London, United Kingdom
Email: [email protected]
Figure 1. An ORTEP representation of [ReOL1] and epifluorescence microscopy of a section of human brain tissue stained with [ReOL3] showing the presence of amyloid plaques.
Alzheimer’s disease (AD), the most common neurodegenerative condition, is characterised by the formation of
insoluble plaques in the brain that primarily consist of aggregated forms of the amyloid-β (Aβ) peptide. The role that Aβ aggregation plays in the development and progression of AD remains elusive. The synthesis of compounds that can bind to Aβ aggregates and assist in the clinical diagnosis of AD are of great interest and
may aid in further understanding of AD pathology.1
Technetium-99m is the most commonly utilised radionuclide for single-photon-emission computed tomography
(SPECT) imaging and is used in >85% of all diagnostic nuclear scans. There is great clinical relevance in the
design of technetium-99m complexes that can cross the blood-brain barrier and enable diagnostic imaging of
brain pathology. Such complexes must be charge-neutral, lipophilic and stable under biological conditions. As
there are no stable isotopes of technetium, its group seven congener rhenium is utilised for exploratory synthesis
and characterisation.
A series of three ligands that feature an N3S donor set have been developed with the aim of forming stable,
charge-neutral complexes with the oxorhenium(V) and oxotechnetium(V) cores. The complexes include an
integrated amyloid-targeting styrylpyridyl group and can bind to amyloid plaques on human brain tissue. The
synthesis and characterisation of the rhenium complexes by conventional spectroscopy and X-ray
crystallography will be discussed alongside investigation of their interactions with Aβ. Additionally, two of the
ligands were radiolabelled with technetium-99m under mild conditions using a kit-based approach and the
radiolabelled complexes were studied in wild-type mice to assess their in vivo properties.
1. K. Chen, M. Cui, Medchemcomm, 2017, 8, 1393
94
SEMICONDUCTIVITY AND SPONTANEOUS MAGNETISATION IN A MIXED-VALENCE IRON(III)-CHLORANILATE
FRAMEWORK
Martin P. van Koeverden1*, Carol Hua1, Timothy A. Hudson1, Guy N. L. Jameson1,2, Keith S. Murray3, Wasinee Phonsri3, Ashley L. Sutton1, Richard Robson1, Deanna M. D’Alessandro4 and
Brendan F. Abrahams1
1School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia 2Bio21 Molecular Science and Biotechnology Institute, Parkville, Victoria, Australia
3School of Chemistry, Monash University, Clayton, Victoria, Australia 4School of Chemistry, The University of Sydney, Sydney, NSW, Australia
Email: [email protected]
Electrically conductive coordination polymers are an emerging class of compounds with diverse applications,
due to the potential for synergistic combination of conductivity and porosity in a material, compared to non-
porous inorganic (semi)conductors.[1] Introduction of mixed-valency into coordination polymers, achieved by incorporation of electroactive metals and/or ligands in multiple formal oxidation states, has emerged as a
powerful technique to engender bulk electronic conductivity to these materials.[2] The deprotonated forms of
2,5-dihydroxy-1,4-benzoquinone (H2dhbq) and the 3,6-dihalogenated analogues (anilic acids, H2Xan, X = F,
Cl, Br) exhibit three readily accessible redox states: a quinonoid dianion, a paramagnetic semiquinonoid trianion, and an aromatic tetraanion. Frameworks which contain these ligands in multiple oxidation states may
thus exhibit bulk electronic conductivity[3, 4] and magnetic ordering.[5, 6] Viologens are a class of dicationic
molecules which can also exist in multiple redox states,[7] as well as readily participating in charge transfer interactions with π-electron donating molecules. However, the influence upon the structure and properties of anionic anilate frameworks following incorporation of these electroactive dications has been largely unexplored.
The synthesis and characterisation of an iron-chloranilate coordination polymer incorporating a viologen
dication (1·4DMF) is presented. A combination of single-crystal X-ray diffraction, 57Fe Mössbauer and electronic spectroscopy revealed 1·4DMF is a 2D anionic iron(III)-chloranilate network with ligand-based mixed-valency. Variable-temperature electrical conductivity measurements demonstrated 1·4DMF exhibits
thermally activated semiconductor behaviour, with a room-temperature conductivity of 5.6 × 10−4 S cm−1 and
an activation energy of 0.25 eV. Additionally, dc and ac magnetometry showed the presence of spontaneous ferrimagnetic ordering below 31 K, resulting from antiferromagnetic coupling between iron(III) and paramagnetic chloranilate radical trianion ligands.
[1] L. Sun, M. G. Campbell, M. Dincă. Angew. Chem. Int. Ed. 2016, 55, 3566.
[2] M. G. Campbell, D. Sheberla, S. F. Liu, T. M. Swager, M. Dincă. Angew. Chem. Int. Ed. 2015, 54,
4349.
[3] R. Murase, B. F. Abrahams, D. M. D’Alessandro, C. G. Davies, T. A. Hudson, G. N. L. Jameson, et al.
Inorg. Chem. 2017, 56, 9025.
[4] L. E. Darago, M. L. Aubrey, C. J. Yu, M. I. Gonzalez, J. R. Long. J. Am. Chem. Soc. 2015, 137, 15703.
[5] I.-R. Jeon, B. Negru, R. P. Van Duyne, T. D. Harris. J. Am. Chem. Soc. 2015, 137, 15699.
[6] J. A. DeGayner, I.-R. Jeon, L. Sun, M. Dincă, T. D. Harris. J. Am. Chem. Soc. 2017, 139, 4175.
[7] C. L. Bird, A. T. Kuhn. Chem. Soc. Rev. 1981, 10, 49.
95
BIS-DITHIOCARBAZATE LIGANDS AND THEIR NON-INNOCENT RELATIONSHIP WITH COPPER
Jessica K. Bilyj1*, Nicole V. Silajew1, Graeme R. Hanson2, Jeffrey R. Harmer2
and Paul V. Bernhardt1 1School of Chemistry and Molecular Biosciences,The University of Queensland, Brisbane, Australia
2Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
Email: [email protected]
The ability for acetylacetone derived dithiocarbazate ligands to stabilise high oxidation state metal complexes has been demonstrated previously in complexation with copper due to their extensive charge delocalisation and
ability to deprotonate the acetylacetone moiety to provide a trianionic ligand.1 These ligands can be categorised as non-innocent and have provided some interesting properties in the past with comparable thiosemicarbazone
complexes of nickel and copper.2,3 Herein, ligands derived from acetylacetone and S-methyl or S-benzyl
dithiocarbazates complexed with copper under anaerobic conditions provide reactive CuII complexes, which
upon exposure to O2, oxidise to an intermediary CuIII complex. This CuIII intermediate was found to convert to two products, a ligand oxidised derivative with a ketone group installed at the apical C of the acetylacetone
moiety or a binuclear complex connected via C-C coupling of two respective CuIII complexes through the apical C of the acetylacetone moiety. This bifurcating pathway can be controlled through the use of base to only observe the dimer.
1. M. Akbar Ali, P. V. Bernhardt, M. A. H. Brax, J. England, A. J. Farlow, G. R. Hanson, L. L. Yeng, A. H. Mirza, K. Wieghardt, Inorg. Chem., 2013, 52, 1650–1657.
2. J. K. Bilyj, J. R. Harmer, P. V. Bernhardt, Eur. J. Inorg. Chem., 2018, 43, 4731–4741.
3. J. K. Bilyj, M. J. Riley, P. V. Bernhardt, Dalton Trans., 2018, 47, 2018–2030
96
INVESTIGATING THE CHEMISTRY OF SILVER IN BIOLOGICAL SYSTEMS
Harley D. Betts1*, Stephanie L. Neville2, Christopher A. McDevitt2, Christopher J. Sumby1 and Hugh
H. Harris1, 1The University of Adelaide, SA, Australia
2The University of Melbourne, Victoria, Australia Email: [email protected]
The antibacterial properties of silver have been known for centuries,1 however, the threat of antibiotic resistant bacteria has
led to renewed focus on the noble metal. Silver is now commonly included in a range of household and medical items,
such as deodorants and bandages,2 though the chemical fate of the metal when exposed to mammalian or bacterial
biological systems is poorly understood.3 Through the use of a metallomics approach, using techniques like X-ray
absorption spectroscopy (XAS), and size-exclusion chromatography hyphenated inductively coupled plasma mass
spectrometry (SEC-ICP-MS), results are presented that advance our understanding of the chemistry of these interactions.
In human blood and bacterial cells, silver was found to be associated with high molecular weight, likely proteinaceous
species, with the speciation of the metal dominated by interactions with cysteine residues. When exposed to human whole
blood, silver was found to rapidly migrate into the red blood cells with ~90% of the metal localised here. The silver that
remained in the plasma was predominantly bound by human serum albumin and other high molecular weight plasma
proteins. XAS experiments also yielded information regarding the necessity to examine biological systems as a whole
rather than the sum of their parts. The speciation of silver when exposed to isolated human plasma was found to resemble
solid silver chloride, however, when added to whole blood and subsequently fractionated the speciation in the plasma was
similar to thiolate-bound silver.
In bacteria, endogenous silver was found to be almost exclusively co-localised with copper-binding proteins, providing
insight into the intracellular localization of the metal in bacteria. Copper is a strictly regulated essential micronutrient,
largely confined to the periplasmic or extracellular space of the organisms.4 Building on this knowledge, silver-loaded
porous materials embedded in polymer matrices have been tested for their efficacy as antibacterial agents.
References
1. Alexander, J. W., History of the medical use of silver. Surg Infect (Larchmt) 2009, 10 (3), 289-92.
2. Sim, W.; Barnard, R. T.; Blaskovich, M. A. T.; Ziora, Z. M., Antimicrobial Silver in Medicinal and Consumer
Applications: A Patent Review of the Past Decade (2007-2017). Antibiotics (Basel) 2018, 7 (4).
3. Eckhardt, S.; Brunetto, P. S.; Gagnon, J.; Priebe, M.; Giese, B.; Fromm, K. M., Nanobio silver: its interactions
with peptides and bacteria, and its uses in medicine. Chem Rev 2013, 113 (7), 4708-54.
4. Stewart, L. J.; Thaqi, D.; Kobe, B.; McEwan, A. G.; Waldron, K. J.; Djoko, K. Y., Handling of nutrient copper in
the bacterial envelope. Metallomics 2019, 11 (1), 50-63.
97
Wednesday 18th
December
Session 2
98
THE THERAPEUTIC VERSATILITY OF RUTHENIUM(II) COMPLEXES
F. Richard Keene*1,2
and J. Grant Collins3
1School of Physical Sciences, University of Adelaide, Adelaide, SA, Australia
2Australian Institute of Tropical Health & Medicine, James Cook University , Townsville, QLD, Australia
3School of Science, UNSW Canberra @ Australian Defence Force Academy, Canberra , A.C.T. Australia
Email: [email protected]
Despite the clinical success of platinum-based anticancer drugs, their limitations have led to considerable
interest in the development of new therapeutic agents based upon other transition metals – in particular
ruthenium – and there have now been many studies demonstrating the anticancer and antimicrobial
properties of polypyridylruthenium(II) complexes. More importantly, a handful of recent studies have now
demonstrated these ruthenium complexes can exhibit therapeutic activity in vivo. Polypyridylruthenium(II)
complexes can selectively bind: to particular nucleic acid sequences and structures; to important enzymes;
and target specific intracellular organelles (mitochondria, the nucleus, the nucleolus, the endoplasmic
reticulum, and lysosomes).[1]
As the syntheses of these ruthenium(II) complexes are modular, the structure
can be readily modified (size, shape, stereochemistry, charge, lipophilicity, hydrogen bonding
donors/acceptors, etc.) to obtain the required biological properties. The metal complexes represent the
development of a new class of biologically-active compounds, rather than maintaining a dependence on the
manipulation of existing scaffolds in the treatment of disease.
This presentation will discuss these design features as applied to anticancer and antimicrobial activity, but
will emphasise recent in vitro and in vivo studies in which polypyridylruthenium(II) complexes act as
antiparasitic agents (against Schistosoma spp.), and as antifungal agents against Cryptococcus neoformans
[1] X. Li, A.K. Gorle, M.K. Sundaraneedi, F.R. Keene and J.G. Collins, Coord Chem Rev 2018, 375, 134.
99
INVESTIGATING THE BIOLOGICAL INTERACTIONS OF MONOFUNCTIONAL PLATINUM COMPLEXES
Marcus E. Graziotto*1, Trevor Hambley1 and Elizabeth New2* 1School of Chemistry, The University of Sydney, NSW, Australia
Email: [email protected]
+
H3N Pt
H3N
Pyriplatin
+
H2 N
Pt
N H2
Enpyriplatin
The continued use of cisplatin and its analogues in clinical settings is marred by the side effects experienced
patients and the inherent resistance of certain cancers to these drugs. As such, there is a renewed interest in
understanding the interactions of these compounds with cells at the molecular level.
We have studied the biological interactions of monofunctional platinum(II) complexes as these types of compounds are currently in clinical trials. We studied the properties of pyriplatin and enpyriplatin, a pair of
complexes with similar coordination spheres and only differ by a chelating ligand.1 In colorectal cancer cells,
these compounds were found to have vastly different cytotoxicities after 72 h (pyriplatin IC50 = 6.5 M,
enpyriplatin IC50 > 300 M). We established that this difference was not due to the lipophilicity or ability of the complex to bind to DNA, but the extent to which the complex accumulates inside the cells. Cells treated with pyriplatin exhibited a time dependent increase of platinum accumulation, whereas the amount of platinum in cells treated with enpyriplatin was invariant with time, suggesting that interactions with transporters are vital for these types of compounds. For the first time, we have utilised size exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICP-MS) to determine the extent to which these compounds bind to cytoplasmic proteins. We observed distinctive protein binding by cisplatin and the monofunctional platinum complexes with levels that correlated to the whole-cell accumulation. It also revealed a minimal disruption of the native copper, iron and zinc proteins by the platinum complexes.
We are currently utilising fluorescence-based techniques in order to understand the metabolism of these complexes in cells. We have investigated the effect of cisplatin on copper homeostasis with a fluorescently
labelled copper influx transporter (CTR1)2 as well as the fluorescent mitochondrial copper sensor InCCu1.3
We demonstrated that cisplatin interferes with the copper homeostasis system by redistributing copper within
the cell. We are continuing to use our probe for monofunctional platinum complexes FDCPt14 as well as our fluorescent redox sensors to obtain complementary information about how these complexes and their metabolites influence oxidative stress during chemotherapeutic treatment.
References:
1. M.E. Graziotto, M.C. Akerfeldt, A.P. Gunn, K. Yang, M.V. Somerville, N.V. Coleman, B.R. Roberts,
T.W. Hambley, E.J. New. J. Inorg. Biochem., 2017, 177, 328. 2. M.C. Akerfeldt, C.M.-N. Tran, C. Shen, T.W. Hambley, E.J. New. J. Biol. Inorg. Chem., 2017, 22, 765.
3. C. Shen, J.L. Kolanowski, C.M.-N. Tran, A. Kaur, M.C. Akerfeldt, M.S. Rahme, T.W. Hambley, E.J.
New. Metallomics, 2016, 8(9), 915.
4. C. Shen, B.D.W. Harris, L.J. Dawson, K.A. Charles, T.W. Hambley, E.J. New. Chem. Commun. 2015, 51, 6312.
2+
H3N N Pt
H3N OH2
N
Cl
N
Cl
100
SEMICARBAZONE AND THIOSEMICARBAZONE MACROCYCLIC CHELATORS WITH POTENTIAL
RADIOPHARMACEUTICAL APPLICATIONS
Brett M. Paterson1* 1School of Chemistry, Monash University, VIC, Australia
Email: [email protected]
Figure 1. X-ray crystal structures of a semicarbazone tetrazamacrocycle (left) and the Pb2+ (middle) and Bi3+ (right)
Semicarbazone and thiosemicarbazone molecules are examples of Schiff bases that are produced through condensation reactions between carbonyl groups and semicarbazides or thiosemicarbazides, respectively. Semicarbazones have demonstrated antimicrobial and anticonvulsant activities. Thiosemicarbazones have a wide range of pharmacological activity that is consistently linked to their ability to chelate metal ions. In
addition, thiosemicarbazones have also been investigated in radiopharmaceuticals of 64
Cu for positron
emission tomography (PET) of blood perfusion, hypoxia and Alzheimer’s disease.1
The promise of thiosemicarbazone- and semicarbazone-based radiopharmaceuticals has led us to investigate their potential
applications with other radioactive isotopes such as the -emitters 212
Bi/212
Pb and 213
Bi and the positron
emitters 68
Ga, 64
Cu, 52
Mn and 55
Co.2,3
New variants of 1,4,7,10-tetraazacyclododecane (cyclen) bearing semicarbazone or thiosemicarbazone
pendant groups have been prepared. The semicarbazone variant forms 8-coordinate complexes with Bi3+
and
Pb2+
(Figure 1). The ligand was radiolabelled within 5 min with the -emitting radioactive isotope 213
Bi, which is used in systemic targeted radiotherapy, and the resulting complex was stable in serum for at least 90
min (two decay half-lives). The thiosemicarbazone variant forms 6-coordinate complexes with Ga3+
, Mn2+
,
Cu2+
and Co2+
. The Mn2+
and Co2+
complexes were characterized by X-ray crystallography. A radiochemical
yield (>95%) was obtained for the 68
Ga complex.
1. B. M. Paterson, P. S. Donnelly, Chem Soc. Rev., 2011, 40, 3005.
2. S. Hassfjell, M. W. Brechbiel, Chem. Rev. 2001, 101, 2019. 3. A. Morgenstern, F. Bruchertseifer, C. Apostolidis, Curr. Radiopharm. 2011, 4, 295.
101
SYNTHESIS AND G-QUADRUPLEX DNA BINDING PROPERTIES OF NICKEL SCHIFF BASE COMPLEXES
Son Q.T. Pham1*, Kimberley J. Davis1, Haibo Yu1, Anthony C. Willis2, Christopher Richardson1,
Jennifer L. Beck1 and Stephen F. Ralph1
1School of Chemistry and Molecular Bioscience, University of Wollongong, NSW, 2522 2Research School of Chemistry, Australian National University, Canberra, ACT, 2601
Email: [email protected]
Figure 1. (a) ESI mass spectrum of a solution containing a 3:1 ratio of (1) and parallel tetramolecular G-
quadruplex DNA Q4, (b) ESI mass spectrum of a solution containing a 3:1 ratio of (1) and the 16 mer duplex
DNA D2, (c) X-ray crystallography structure of (1), (d) A molecular docking result using (1) and G-
quadruplex DNA 1KF1.
DNA strands containing guanine rich sequences are able to form secondary structures named G-quadruplex DNA (qDNA) which play an important role in the regulation of oncogenes, and also have the potential to
inhibit the activity of telomerase.1,2
Due to the prevalence of double stranded DNA (dsDNA) in living cells, the search for distinctly selective and efficient qDNA stabilizers is still a grand challenge. Herein, we report a series of novel nickel benzophenone complexes such as (1), which possess high affinity and selectivity towards qDNA over dsDNA. The complexes have been characterised by X-ray crystallography in the solid state and by electrospray ionisation mass spectrometry (ESI-MS) and NMR spectroscopy in solution. The
interactions between the complexes and dsDNA, human telomeric qDNA (Q1), and tetramolecular qDNA (Q4), have been studied using circular dichroism (CD) spectroscopy, ESI-MS, fluorescence indicator displacement (FID), fluorescence resonance energy transfer (FRET) melting assays and molecular docking. These studies have showed that many of the novel complexes are effective qDNA binders. In particular, the ESI-MS results indicated (1) has a high degree of selectivity for qDNA over dsDNA. This will be valuable in further exploratory studies into these novel metal complexes as potential anticancer drugs.
References
1. K.J. Davis, N.M.O. Assadawi, S.Q.T. Pham, M.L. Birrento, C. Richardson, J.L. Beck, A.C. Willis,
and S.F. Ralph, Dalton Trans., 2018. 47(38): p. 13573-13591.
2. J.E. Reed, A.A. Arnal, S. Neidle, and R. Vilar, J. Am. Chem. Soc., 2006. 128(18): p. 5992-5993.
102
INTERACTIONS OF POLYPYRIDYL RUTHENIUM COMPLEXES WITH NON-CANONICAL AND FLAWED DNA
Benjamin J. Pages1*, Sarah P. Gurung2,3, Kane McQuaid2,3, James P. Hall1,3, Christine J. Cardin2
and John A. Brazier1
1School of Pharmacy, University of Reading, Reading, UK 2Department of Chemistry, University of Reading, Reading, UK
3Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK Email: [email protected]
Transition metal complexes have been used for decades as fluorescent cellular probes, DNA binders and
anticancer therapeutics.1 We have previously studied derivatives of the luminescent complex
[Ru(phen)2(dppz)]2+ (where phen = 1,10-phenanthroline; dppz = dipyrido[3,2-a:2’3’-c]phenazine), in which we have used spectroscopic and crystallographic methods to determine detailed information about the binding of
these complexes to DNA.2-4 While binding to DNA in general has good medicinal utility, focus has shifted toward targeting specific structural features of duplexes and sequences that form non-duplex tertiary structures,
as each of these has biological relevance in diseases such as cancer.5-7 Presented here are spectroscopic studies
of [Ru(phen)2(dppz)]2+ and derivatives bound with i-motif DNA8 and duplex DNA containing mismatched base
pairs. We reveal the structure stabilisation effect of [Ru(phen)2(dppz)]2+ on i-motif DNA with various thymine
loop lengths and compare the binding behaviour of Λ and Δ-[Ru(phen)2(dppz)]2+ with several duplexes containing mismatched base pairs.
References
1. B. J. Pages, D. L. Ang, E. P. Wright and J. R. Aldrich-Wright. Dalton Trans., 2015, 44, 3505.
2. K. McQuaid, J. P. Hall, L. Baumgaertner, D. J. Cardin and C. J. Cardin. Chem. Commun., 2019, 55, 9116.
3. J. P. Hall, S. P. Gurung, J. Henle, P. Poidl, J. Andersson, P. Lincoln, G. Winter, T. Sorensen, D. J. Cardin,
J. A. Brazier and C. J. Cardin. Chem. - Eur. J., 2017, 23, 4981.
4. J. P. Hall, P. M. Keane, H. Beer, K. Buchner, G. Winter, T. L. Sorensen, D. J. Cardin, J. A. Brazier and C.
J. Cardin. Nucleic Acids Res., 2016, 44, 9472.
5. M. Düchler. J. Drug Targeting, 2012, 20, 389.
6. H. Abou Assi, M. Garavís, C. González and M. J. Damha. Nucleic Acids Res., 2018, 46, 8038.
7. L. Eberst, M. Brahmi and P. A. Cassier. Bull. Cancer, 2017, 104, 988.
8. B. J. Pages, S. P. Gurung, K. McQuaid, J. P. Hall, C. J. Cardin and J. A. Brazier, Front. Chem., 2019, 7,
744.
9. A. T. Phan, M. Guéron and J.-L. Leroy, J. Mol. Biol., 2000, 299, 123. (Image from PDB file 1EL2)
103
ISOLATION OF MOLECULAR CATALYSTS IN CRYSTALLINE FRAMEWORKS
R. Peralta1, M. Huxley1, C. J Sumby,1 C. J. Doonan1* 1School of Physical Sciences, The University of Adelaide, SA, 5005
Email: [email protected]
The development of new catalysts is crucial to meeting the changing demands in chemical markets and to
address environmental concerns presented by current processes. Our research is focused on isolating
homogeneous catalysts in porous, crystalline matrices to afford well-defined active sites poised to carry out,
industrially attractive, solid-gas reactions [1-3]. This talk will cover our recent work in the area of alkene
hydrogenation and isomerisation chemistry.
[1] W. M. Bloch, et. al Nature Chem. 6, 2014, 906.
[2] A. Burgun e.t al., Angew. Chem. Int. Ed. 2017, 129, 8532.
[3] M. Huxley et. al. J. Am. Chem. Soc. 2018, 140, 6416.
104
BODIPY-COBALOXIME COMPLEXES FOR PHOTOCATALYTIC HYDROGEN PRODUCTION
Stephanie A. Boer1*, Bowen Liu2, Hannah Matthews2, Deepika Kanyan2, David. C. Ware2 and
Penelope J. Brothers1
1 Research School of Chemistry, Australian National University, Canberra, ACT, Australia. 2School of Chemical Sciences, University of Auckland, New Zealand
Email: [email protected]
The increasing demand for energy and the world’s diminishing fossil fuel reserves has motivated widespread
research into the use of hydrogen as a clean and renewable energy source. Photocatalysis is a promising
approach to water splitting to produce hydrogen. It traditionally involves three components; a metal-based
catalytic centre, a photosensitiser which can be excited by light leading to donation of electrons to the catalytic
metal, and a sacrificial electron donor. Photocatalytic systems based on cobaloxime catalysts have shown some
very promising water reduction properties when paired with a suitable photosensitiser and electron donor.
BODIPY is an organo-boron compound which is targeted as a photosensitiser due to its tuneable fluorescence,
high absorption coefficient, excellent chemical stability, solubility and weak non-radiative decay.1
Single component systems which incorporate a catalyst and photosensitiser have shown increased catalytic
activity compared with multi-component systems. It is well known that a cobaloxime can incorporate a BF2
moiety, which provided motivation to explore the covalent attachment of a BODIPY photosensitiser to a cobaloxime catalyst, to make a single-component photocatalytic system. The Brothers group have recently
reported a fast and clean synthesis of O-BODIPY molecules,2 allowing us to covalently attach BODIPY to cobaloxime catalysts. Brominated BODIPY was also incorporated into the photocatalyst, as it has been established that heavy atoms facilitate intersystem crossing, thus producing a long-lived triplet state which is
required for efficient transfer of electrons to the catalyst.3 The use of BODIPY as a photosensitiser also removes the need for the use of expensive metals such as ruthenium or platinum, which are used in traditional
photosensitiser complexes such as [Ru(bpy)3]+.
References:
1. A. Loudet; Burgess, K. Chem. Rev. 2007, 107, 4891. 2. B. Liu; Novikova, N.; Simpson, M. C.; Timmer, M. S. M.; Stocker, B. L.; Söhnel, T.; Ware, D. C.; Brothers,
P. J. Org. Biomol. Chem. 2016, 14, 5205.
3. R. P. Sabatini; McCormick, T. M.; Lazarides, T.; Wilson, K. C.; Eisenberg, R.; McCamant, D. W. J. Phys.
Chem. Lett. 2011, 2, 223.
105
THE ALLURE OF SILVER: SILVER(I)AMIDES AS CATALYSTS IN HYDROFUCTIONALISATION REACTIONS
Samantha A. Orr1, John R. Kelly,
1 Aaron J. Boutland
1 and Victoria L. Blair
1*
1School of Chemistry, Monash University, Wellington Road, Clayton, Melbourne, VIC, Australia
Email: [email protected]
Of the Group 13 ‘coinage metals’, silver is often overlooked in comparison to copper and gold, probably due to
its modest Lewis acidity and light instability. However, this has not hindered Silver salts (e.g AgX X = halide,
OTf, BF6 etc.,) as synthetically useful Lewis acid promoters, additives in Pd-catalysed reactions or as catalysts
in a range of organic transformations including carboxylation, cycloadditions and asymmetric reactions.[1]
Recently, hydrosilylation of aldehydes was achieved using the silver(I)salts AgOTF[2]
or AgPF6[3]
as a catalyst,
but required addition of base, an excess of coordinating ligand and elevated temperatures (70-100). Moving
away from traditional silver(I)salt systems, here we report the design, synthesis and structural characterisation
of a series of silver(I)amide complexes that are efficient molecular pre-catalysts in the hydrosilylation and
hydroboration of aldehydes and ketones. These silver(I)amides are hydrocarbon soluble achieving efficient
reduction of carbonyl substrates at room temperature. While probing the reaction mechanism with control
reactions we suggest a ‘Ag-H’ species is the active catalyst.
References:[1] a) Lewis Acids in Organic Synthesis (Ed. H. Yamamoto), Wiley-VCH, Weinheim, 2000. b) H.
Pellissier, Chem. Rev., 2016, 116, 14868. c)K. Sekine and T. Yamada, Chem. Soc. Rev., 2016, 45, 4524. [2] B.
M. While and M. Stradiotto, Chem. Commun., 2006, 4104. [4] Z. Jia, M. Liu, X. Li, A. S. C. Chan, C-J. Li,
Synlett, 2013, 24, 2049.
106
DEVELOPMENT OF TETHERED DUAL CATALYSTS: SYNERGY BETWEEN PHOTO- AND TRANSITION METAL
CATALYSTS FOR ENHANCED CATALYSIS
Danfeng Wang,1* Indrek Pernik,1 Sinead.T.Keaveney,1 and Barbara Messerle1,2
1Macquarie University, Sydney, NSW, Australia 2The University of Sydney, Sydney, NSW, Australia
Email: [email protected]
Catalysis is a powerful tool in modern synthetic chemistry1 and the paradigms for developing new catalysts encompass ligand design, choice of metal, valence change and selection of the catalyst activation mode (e.g.
thermal vs photo activation). More recently, the emerging strategy of dual catalysis2 has attracted a great deal of attention as it can enable access to organic transformations that have been challenging to achieve. Of particular interest is the new reactivity that dual catalysis can provide when merging photocatalysis and transition metal catalysis. However, to date approaches to dual photochemical/transition metal catalysis have been focused on mixing individual photochemical and transition metal catalysts. Instead, we have been
interested in developing tethered dual catalysts in order to investigate the potential of achieving synergistic enhancements in catalysis.
In this work, we synthesised a series of tethered dual catalysts where Ir and Pd complexes were tethered to a
BODIPY photocatalyst, and investigated the catalytic competencies of these catalysts for promoting both
transition metal and photocatalytic reactions, as well their use in dual catalysis strategies. Extensive
characterisation, including transient absorption spectroscopy (TA), cyclic voltammetry (CV) and X-ray
absorption spectroscopy (XAS), suggest that there are synergistic interactions between the catalysts. The
tethered dual catalysts were more effective at promoting photooxidation and transition metal catalysis, such as
dihydroalkoxylation and Suzuki-Miyaura cross coupling, relative to the un-tethered species, highlighting that
enhancements in both photocatalysis and transition metal catalysis can be achieved. The potential of these
catalysts was further demonstrated through novel sequential reactivity, and through switchable reactivity that is
controlled by external stimuli (heat or light).
Figure 1, Tethered dual catalyst promoted tandem and switchable reactions.
References: 1. Q.-L. Zhou, Angew. Chem., Int. Ed., 2016, 55, 5352-5353.
2. K. L. Skubi, T. R. Blum and T. P. Yoon, Chem. Rev., 2016, 116, 10035-10074.
107
RHODIUM CATALYSED DEHYDROPOLYMERISATION OF AMINE-BORANES
Annie L. Colebatch,1,2* Gemma M. Adams,2 Nicholas A. Beattie,3 Benjamin W. Hawkey Gilder,2
Alasdair !. McKay,2 Stuart A. Macgregor3 and Andrew S. Weller2
1 Australian National University, Canberra, Australia 2 University of Oxford, Oxford, United Kingdom
3 Heriot Watt University, Edinburgh, United Kingdom
Email: [email protected]
H R'
H R' PR2
H N cat. N B H B
Rh H
H R
Amine–borane
– H2 H R
Polyaminoborane
PR2
cat. e.g.
The dehydropolymerisation of amine-boranes (H3BNRH2) for the preparation of polyaminoboranes
(H2BNRH)n, inorganic analogues of ubiquitous polyolefins, has attracted considerable attention1-2 since the first
report in 2008.3 A range of transition metal complexes are now known to catalyse the formation of
polyaminoboranes featuring early, mid and late transition metals.4 However, significant challenges exist in understanding how these catalysts function, and attaining control over the nature of the polymer produced. This
presentation will outline progress we have made using [Rh(diphosphine)]+ based catalysts to elucidate mechanisms of amine-borane dehydropolymerisation, including the first detailed catalyst structure activity
relationship studies.5,6 The nature of the catalyst structure and charge has been found to have a dramatic influence on the efficiency and mechanism of catalysis using these systems, and highlights the importance of ligand tuning to deliver high performance systems.
1 E. M. Leitao, T. Jurca, I. Manners, Nat. Chem. 2013, 5, 817. 2 A. L. Colebatch, A. S. Weller, Chem. Eur. J. 2019, 25, 1379. 3 A. Staubitz, A. P. Soto, I. Manners, Angew. Chem. Int. Ed. 2008, 47, 6212. 4 D. Han, F. Anke, M. Trose, T. Beweries, Coord. Chem. Rev. 2019, 380, 260. 5 G. M. Adams, A. L. Colebatch, J. T. Skornia, A. I. McKay, H. C. Johnson, G. C. Lloyd-Jones, S. A. Macgregor,
N. A. Beattie, A. S. Weller, J. Am. Chem. Soc. 2018, 140, 1481. 6 A. L. Colebatch, B. W. Hawkey Gilder, G. R. Whittell, N. L. Oldroyd, I. Manners, A. S. Weller, Chem. Eur.
J. 2018, 24, 5450.
O n
108
Thursday 19th
December
Session 1
109
FROM ANTIMONY TO GALLIUM: NEW METAL COMPLEXES FOR COMBATING LEISHMANIASIS
Rebekah N. Duffin,1 Victoria L. Blair,1 Lukasz Kedzierski2 and Philip C. Andrews1*
1 School of Chemistry, Monash University, Clayton, Melbourne, VIC 3800, Australia 2 Faculty of Veterinary and Agricultural Sciences at The Peter Doherty Institute for Infection and Immunity,
Melbourne, VIC 3000, Australia
Email: [email protected]
Even after 80 years, Sb(V) compounds sodium stibogluconate (PentostamTM) and meglumine antimoniate
(GlucantimeTM) remain the most important and cost-effective drugs for treating the deadly parasitic infection
Leishmania.1
Unfortunately, these Sb(V) compounds are not optimal: they are delivered over 28 days by painful intramuscular injection; highly toxic Sb(III), the likely active form of the drug, is produced and bio-distributed through
intracellular reduction of Sb(V); and resistance has appeared in some parts of India.2 Alternative drugs; Amphotericin B, Pentamidine and Miltefosine, while effective, remain expensive and also have severe side
effects.3
Iron, gallium and bismuth are three metals which can exist in the +III oxidation state and are known to bind to
similar proteins in the body. While Fe is unique in the triad as being the only endogenous metal, both gallium
and bismuth are known to be biologically and medicinally relevant metals. It should be possible to design
antimicrobial compounds that utilize and subvert the Fe transport, storage and utilization mechanisms.4
Over the years, we have studied new and more lipophilic organometallic antimony complexes with the potential for oral delivery. We have also examined new bismuth compounds as possible safer alternatives to antimony- based drugs because of the noted low systemic toxicity of Bi in humans. While Bi(III) complexes are showing
promise, Bi(V) complexes have been shown to be too unstable and too toxic to mammalian cells.5
Gallium compounds can show good antimicrobial activity, and are also of low toxicity towards humans. This
has led to increasing interest in gallium and its potential applications in materials, medicine and bio-protective
surfaces.
In this context we recently targeted, synthesised and characterised a range of novel organometallic Ga(III)
quinolinolates and subsequently studied the in vitro toxicity towards Leishmania major promastigotes and
amastigotes (the clinically relevant form), and to human fibroblasts.
In this presentation, we describe the chemistry of these compounds and compare their anti-parasitic activity and
cytotoxic behaviour with Sb and Bi compounds, and assess their overall potential as future drugs.
1. Y. C. Ong, S. Roy, P. C Andrews, G. Gasser. Chem. Rev., 2018, 119, 730-796.
2. A. K. Haldar, P. Sen, A. Kumar, S. Roy. Mol. Biol. Int., 2011, 2011, Article ID 571242: D. Légaré, M.
Ouellette. Handbook of Antimicrobial Resistance, 2017, 313-341.
3. J. V. Richard, K. A. Werbovetz. Curr. Opin. Chem. Biol. 2010, 14, 447.
4. C. R. Chitambar, Int. J. Environ. Res. Public Health 2010, 7, 2337-2361
5. R. N Duffin, V. L Blair, L.; Kedzierski, P. C Andrews. Dalton Trans., 2018, 47, 971-980.
110
NATURAL PRODUCT DRUG DISCOVERY – A METAL-ASSISTED APPROACH
Lukas M. Roth1*, Michael P. Gotsbacher and Rachel Codd 1The University of Sydney, NSW, Australia
Email: [email protected]
In 1990, approximately 80% of medicines approved in the U.S. were either natural products or their
derivatives.[1] In the early 2000s there was a significant drop in the number of natural products in clinical studies,
coinciding with the expansion of high throughput screening (HTS) techniques.[1] However, the limited structural diversity inherent to HTS and the emerging threat of antimicrobial resistance has reinvigorated the focus on
exploiting natural products for the discovery and development of new medicines.[2]
The adaptation of immobilized metal affinity chromatography (IMAC), a technique originally designed for the
isolation of histidine-tagged proteins, has shown promise in isolating and purifying bioactive compounds.[3]
IMAC relies on the fundamentals of coordination chemistry to bind and selectively elute compounds with known metal ion affinity. Although originally developed for recombinant protein purification, this simple method has been shown to readily purify hydroxamic acid siderophores, such as desferrioxamine B (DFOB),
from bacterial cultures[3, 4]. Most IMAC work, in the context of siderophore isolation and purification, has utilized Ni(II) as the metal ion, but there is potential in substituting Ni(II) with other metal ions, such as Cu(II),
Fe(III) and Zn(II).[4] These different metal ions might select for different metabolites as directed by distinct coordination chemistries. This could open up a new way to discover metalloprotein inhibitor-specific drug
candidates as the metabolites, by virtue of their metal binding affinity, may demonstrate activity against various metalloproteins.
As an initial proof of concept, we have exposed a mixture of in use metalloprotein inhibitors to the different
IMAC columns. This is being followed by the application of supernatant from the marine bacteria Salinispora
tropica to the IMAC columns. The metabolites isolated by each column will then be analysed by LC-MS and
taken through a metabolomics workflow for further selection. Promising prospective metalloprotein inhibitors
will undergo screening using a variety of metalloprotein inhibition assays (e.g. angiotensin converting enzyme,
histone deacetylase, and 5-lipoxygenase).
References
[1] J. W. H. Li, J. C. Vederas, Science Review 2009, 325, 5937, 161-5.
[2] M. G. Moloney, Trends in Pharmacological Sciences 2016, 37, 8, 689-701.
[3] N. Braich, R. Codd, The Analyst 2008, 133, 877-80. [4] G. Gasser. Inorganic Chemical Biology : Principles, Techniques and Applications 2014. New York: John
Wiley & Sons, Incorporated.
111
MECHANISTIC INSIGHT INTO STEROID HORMONE BIOSYNTHESIS: WHAT WE LEARN FROM COMPARING SPECIES
Lisandra (Lisa) L. Martin * School of Chemistry, Monash University, Clayton, 3800, Australia
Email: [email protected]
The biosynthetic pathways for steroid hormones begins with cholesterol and uses spatial and temporal control
to direct steroid precursors towards major classes of hormones; (i) mineralocorticoids that control salt balance,
(ii) glucocorticoids that regulate metabolism, (iii) androgens; male sex hormones and (iv) oestrogens; female
sex hormones. Matalloenzymes essential to these transformations are a class of multifunctional cytochrome
P450s. Aromatase is the cytochrome P450 (CYP19A1) enzyme that synthesises oestrogens in a three-step
transformation that requires three molecules of dioxygen and six electrons, transferred by NADPH via the
electron donor cytochrome P450 oxidoreductase (CPR). Once the androgen substrates, androstenedione or
testosterone, are provided to aromatase, they are converted into oestrone and oestradiol, respectively. It is not
surprising that aromatase would have a similar structure and function across all species, as oestrogen is essential
for reproduction, hence fundamental to species abilities to exist. We have compared aromatase amino acid
sequences and the predicted 3D structures across a number of divergent species. These data reveal some subtle
structural variation among species. We have previously shown that human aromatase forms homodimers, using
FRET in live cells, and a QCM-D membrane binding assay.[1] We have also found that pigs are the only mammal
that have more than one aromatase gene(s), and it expresses these in different tissues with very different
activities.[2] Here we present new data on the activity of aromatase across several species and develop a model
for how aromatase might regulate its activity in various species. Finally, we will provide some mechanistic data
to support how we can exploit this for the design of drugs for steroid-fed cancers, such as breast cancers.
Together with data from some other multifunctional cytochrome P450,[3-5] we are beginning to understand the
underlying mechanistic steps needed for steroid biosynthesis by cytochromes P450 enzymes.
1. S. Praporski, S. Ng, A. Nguyen, C.J. Corbin, A. Mechler, J. Zheng, A.J. Conley, L.L. Martin, Organization
of Enzymes Involved in Sex Steroid Synthesis: Protein-protein interactions in lipid layers, J. Biol. Chem.,
(2009), 284(48) 33224-33232.
2. L.L. Martin, J.K. Holien, D. Mizrachi, C.J. Corbin, A.J. Conley, M.W. Parker, R.J. Rodgers, Evolutionary
comparisons predict that dimerization of cytochrome P450 aromatase increases enzymatic activity and
efficiency, J Steroid Biochem. Mol. Biol. (2015) 154, 294-301.
3. A.N. Simonov, J.K. Holien, J.C.I. Yeung, A. Nguyen, C.J. Corbin, J. Zheng, V.L. Kuznetsov, R.J. Auchus,
A.J. Conley, A.M. Bond, M.W. Parker, R.J. Rodgers, L.L. Martin, Mechanistic scrutiny identifies a kinetic
role for cytochrome b5 regulation of human cytochrome P450c17, PLoS One, (2015) 10(11), e0141252.
4. C. Kubeil, J.C.I. Yeung, R.C. Tuckey, R.J. Rodgers, L.L. Martin, Lipid mediates protein-protein
interactions of cholesterol side-chain cleavage cytochrome P450 with its associated electron transport
proteins, ChemPlusChem (2016) 81, 995-1002.
5. J.K. Holien, M.W. Parker, A.J. Conley, C.J. Corbin, R.J. Rodgers, L.L. Martin, A homodimer model can
resolve the conundrum as to how cytochrome P450 oxidoreductase and cytochrome b5 compete for the
same binding site on cytochrome P450c17, Current Proteins & Peptide Science, (2017) 18, 515-517.
112
Organic and Ir(III) Lanthanide Conjugates for Applications in Bio-Imaging and Sensor Developments
Pria Ramkissoon* and Peter J. Barnard La Trobe University, Bundoora VIC 3086, Australia
Email: [email protected]
Luminescent heterobimetallic complexes of iridium (Ir) and lanthanides (Ln) have shown significant potential
in bio-imaging applications.1 The use of highly luminescent cyclometalated Ir(III) complexes conjugated to
lanthanides allows the generation of characteristic Ln emission that can be detected in vivo.1 Properties including
the long lived excited state and wide Stokes shift make Ir(III) complexes efficient energy donors to acceptor Ln
complexes in resonance energy transfer (RET) and Dexter electron transfer systems.2 Similarly, BODIPY and anthracene derivatives have been exploited for their strong luminescence and quantum yields in various
luminescent applications, offering significant potential in RET systems analogous to those based on Ir(III).3, 4
Additionally, the aggregation-induced emission of tetraphenylethylene (TPE) has led to a range of TPE based
luminescent sensors and imaging agents that may also be extended to include RET Ln systems.5 A series these organic and Ir(III) conjugates have been synthesised retaining the same acetamide linkage between the organic or Ir(III) antennae and a lanthanide bound carboxylic acid or amide functionalized cyclen macrocycle (DO3A). The photophysical and electrochemical properties of the organic and Ir(III)-Ln(III) heterobimetallic conjugates will be reported.
References
[1] A. Jana, B. J. Crowston, J. R. Shewring, L. K. McKenzie, H. E. Bryant, S. W. Botchway, A. D. Ward,
A. J. Amoroso, E. Baggaley, M. D. Ward, Inorg Chem. 2016, 55, 5623. [2] D. Sykes, A. J. Cankut, N. M. Ali, A. Stephenson, S. J. P. Spall, S. C. Parker, J. A. Weinstein, M. D.
Ward, Dalton Trans. 2014, 43, 6414.
[3] A. Loudet, K. Burgess, Chem Rev. 2007, 107, 4891.
[4] H. W. Lee, H. J. Kim, Y. S. Kim, J. Kim, S. E. Lee, H. W. Lee, Y. K. Kim, S. S. Yoon, Displays. 2015,
39, 1.
[5] M. Wang, G. Zhang, D. Zhang, D. Zhu, B. Z. Tang, J Mater Chem. 2010, 20, 1858.
113
UNTANGLING THE [M2L3] ↔ [M4L6] EQUILIBIRUM: USING STERICS TO CONTROL CAGE GEOMETRY
Rashid G. Siddique and Jack K. Clegg 1* 1School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Qld, 4072
Email: [email protected]
We have prepared a series of phenyl-spaced quaterpridine ligands with a varying degrees of steric bulk situated on the
ligand core. The self-assmebly of these ligands with first-row transition metals to form metallo-supramolecular tetrahedra
has also been performed. Depending on the identity of the metal and bulky substitutent employed, the [M2L3] helicate ↔
[M4L6] tetrahedron equilibrium sits in differnent places, ranging from pure helicate to pure tetrahedron. Employing
comparatively inert metal-ions has allowed for the kinetics and mechanism of helicate ↔ tetrahedron interconversion to
be established.
114
ENGINEERING METAL-ORGANIC CAGE MATERIALS BY SOLUTION PROCESSING
Witold M. Bloch1*, Ravichandar Babarao2, Matthew L. Schneider1
1Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, Australia 2School of Science, RMIT University, Melbourne, Victoria 3001, Australia.
Email: [email protected]
Molecular solids based on cage compounds have recently emerged as an attractive class of porous materials due
to their solution processability and control over pore structure and topology.1 The distinguishing feature of
crystalline cage solids over other materials such as Metal-organic Frameworks (MOFs)2 and Covalent-organic
Frameworks (COFs)3 is that their solid-state packing is directed by weak non-covalent interactions, rather than covalent or coordinative bonds. This engenders molecular cage solids with a degree of solubility and processability, resulting in the possibility to crystallise different polymorphs of the same compound with distinct
porosities. Whilst this phenomenon has been extensively investigated for purely organic cage compounds,1 the solubility and processability of cage solids formed by virtue of metal-ligand bonding has not been examined to the same extent.
Our interest in designing hierarchical materials from cage compounds4 promoted us to investigate whether the
solid-state packing of metal-organic cages can be tuned in the same way as for purely organic cage solids. To
this end, we have prepared a lantern-type Cu4L4 metal-organic cage (1, figure above) which can be obtained in
the solid-state as several different phases depending on the crystallisation conditions. For cage 1, we have
discovered up to five distinct crystalline phases which can interconvert depending on the solvent that the crystals
are exposed to. In our system, three of these phases can be obtained as true polymorphs, displaying distinct
solid-state packing and porosity even in their activated forms. Furthermore, the exterior aldehyde functionality
of 1 allows us to post-synthetically modify the cage via condensation reactions in order to extend the cage
architecture and form predictable packing motifs.
1. T. Hasell, A. I. Cooper, Nat. Rev. Mater., 2016, 1, 16053.
2. H. Furukawa, K. E. Cordova, M. O’Keeffe, O. M. Yaghi, Science, 2013, 341.
3. X. Feng, X. Ding, D. Jiang, Chem. Soc. Rev., 2012, 41, 6010
4. W. M. Bloch, J. J. Holstein, B. Dittrich, W. Hiller, G. H. Clever, Angew. Chemie Int. Ed., 2018, 57, 5534.
115
STRATEGIES FOR ASSEMBLING BOTH DISCRETE AND FRAMEWORK METALLO-SUPRAMOLECULAR
STRUCTURES - FROM POLYROTAXANE GENERATION TO PRESSURE INDUCED MOLECULAR SWITCHING
Leonard F Lindoy* School of Chemistry, The University of Sydney, NSW, Australia
Email: [email protected]
We have employed ligand derivatives incorporating diketonato domains for the construction of a range of unusual supramolecular structures. For example, in earlier studies bis-β-diketonato derivatives, in which the β- diketone fragments are linked via a 1,3- or 1,4-substituted aryl group, have been employed to construct neutral
dinuclear platforms, dinuclear helices, trinuclear triangles, tetranuclear tetrahedrons1 as well as an usual
universal-3-ravel.2 In the case of a [Fe4L6] tetrahedron, post-synthetic capping of the corners was successful in
producing a fully covalently closed tetrahedral cage (see a).3
For Cu(II), several of the platform species are linked via a range of difunctional bridging ligands to yield both new discrete and framework materials that include a unique polyrotaxane in which the “string” and its “beads”
are constructed from the same building blocks (see b).4
A 1D metal organic framework that exhibits remarkable pressure-controlled Cu-N bond breaking/bond forming
switching behaviour has been investigated.5 Overall, the pressure-induced phase change is associated with a
surprising (and non-intuitive) reversible shift in structure - from a 1-dimensional coordination polymer to a
discrete dinuclear complex (see c). The phase change results in the depolymerization of the material through
the cleavage and formation of axial Cu-N bonds as well as “ring flips” of individual axially coordinated 1-
methylpiperazine ligands.
1. A. J. Brock, J. K. Clegg, F. Li, L. F. Lindoy. Coord. Chem. Rev. 2018, 375,106.
2. F. Li, J. K. Clegg, L. F. Lindoy, R. B. Macquart, G. V. Meehan. Nature Comm. 2011, 2:205.
3. C. R. K. Glasson, G. V. Meehan, M. Davies, C. A. Motti, J. K. Clegg, L. F. Lindoy. Inorg. Chem. 2015,
54, 6986.
4. H. Ju, J. K. Clegg, K.M. Park, L. F. Lindoy, S. S. Lee. J. Am. Chem. Soc. 2015, 137, 9535.
5. J. K. Clegg, A. J. Brock, K. A. Jolliffe, L. F. Lindoy, S. Parsons, P. A. Tasker, F. J. White. Chem. Eur. J.
2017, 23, 12480.
116
AROMATICITY AND ANTIAROMATICITY IN PORPHYRIN NANORINGS
Martin D. Peeksa,†,*, Michael Jiraseka, Juliane Q. Gongb, Kirstie McLoughlinc, Takayuki Kobatakea,
Renée Havera, Timothy D. W. Claridgea, Laura M. Herzb, and Harry L. Andersona
a Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK; b Department of Physics, University of Oxford; c Department of Zoology, University of Oxford
† current affiliation: School of Chemistry, University of New South Wales, Sydney, NSW, Australia; Email: [email protected]
Despite being huge π-conjugated macrocycles (>70 π-electrons), porphyrin nanorings are globally non- aromatic. The individual porphyrin centres exhibit local 18-π aromaticity only. However, global macrocyclic
ring currents can be promoted by oxidation or reduction.[1] We have also found that rings containing between five and eight porphyrin subunits exhibit size-dependent global excited-state aromaticity and antiaromaticity
(Baird aromaticity).[2] Aromaticity and antiaromaticity are demonstrated through DFT calculations, NMR
studies for cations and anions, and radiative rate measurements for excited states.
[1] (a) M. D. Peeks, T. D. W. Claridge, H. L. Anderson. Nature 2017, 541, 200–203; (b) M. D. Peeks, M. Jirasek, T. D.
W. Claridge, H. L. Anderson. Angew. Chem. Int. Ed. 2019, 58, 15717–15720.
[2] M. D. Peeks, J. Q. Gong, K. McLoughlin, T. Kobatake, R. Haver, L. M. Herz, H. L. Anderson. J. Phys. Chem. Lett.
2019, 10, 2017–2022
117
CARBON-HALOGEN BOND ACTIVATION BY GROUP 9 METAL NHC COMPLEXES
Graham C. Saunders*1, Hayden P. Thomas,1 Andrew C. Marr,2 Patrick J. Morgan2 and Yue-Ming
Wang2
1School of Science, University of Waikato, Hamilton, New Zealand 2School of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast, UK
Email: [email protected]
Figure 1 Figure 2
The reactions of the N-heterocycle carbene complexes Cp*MCl2(ArFCH2NC3H2NR) with silver(I) oxide are
dependent on the metal M, the fluorinated aryl group ArF and the substituent R, and on whether the reaction mixture is stirred. On stirring, cyclometallation via carbon–fluorine bond activation is observed for the iridium
complexes Cp*IrCl2(ArFCH2NC3H2NMe), ArF = C6HxF3-xF2-2,6, x = 0, 1 (Figure 1), 2, 3.1 A mixture of cyclometallated products arising from carbon–fluorine and carbon–halogen bond activation is observed for
Cp*IrCl2{(C6H3F-2-X-6)CH2NC3H2NMe}, X = Cl, Br, I.2 Cyclometallation via carbon–hydrogen bond
activation occurs exclusively for Cp*MCl2(ArFCH2NC3H2NMe) (M = Ir, ArF = C6H4F-2, C6HF4-2,3,4,5; M =
Rh, ArF = C6HF4-2,3,4,5). A mixture of products arising from cyclometallation via carbon–fluorine and carbon– hydrogen bond activation is observed for Cp*IrCl2(C6F5CH2NC3H2NCH2C6H5). In the absence of stirring, Cp*IrCl2{(C6H3F2-2,6)CH2NC3H2NMe)} activates the carbon–halogen bonds of haloforms, forming
carbonate.3
Carbon–fluorine bond activation does not occur for the rhodium analogues. Instead Cp*RhCl2(C6F5CH2NC3H2NMe) undergoes rhodium–carbon and carbon–carbon bond formation and de-
aromatization of the fluoroaryl ring (Figure 2).4 In the presence of toluoyl chloride re-aromatization occurs, fluoride is released and a dinuclear complex is formed.
1. H. P. Thomas, Y. Wang, F. Lorenzini, S. J. Coles, P. N. Horton, A. C. Marr, G. C. Saunders.
Organometallics, 2017, 36, 960.
2. A. C. Marr, G. C. Saunders, H. P. Thomas, Y. Wang. Inorg. Chim. Acta, 2019, 486, 1.
3. A. C. Marr, P. J. Morgan, G. C. Saunders, H. P. Thomas. Dalton Trans., 2019, 48, 1947.
4. H. P. Thomas, A. C. Marr, P. J. Morgan, G. C. Saunders. Organometallics, 2018, 37, 1339.
118
SUPERPHENYLPHOSPHINES: NANOGRAPHENE-BASED LIGANDS THAT DIRECT COORDINATION AND
BULK ASSEMBLY
Jordan N. Smith1, Laura A. Grose1, James M. Hook2 and Nigel T. Lucas1* 1Department of Chemistry, University of Otago, Dunedin, New Zealand
2Mark Wainwright Analytical Centre, University of NSW, Sydney, Australia Email: [email protected]
Phosphines are ubiquitous throughout coordination and organometallic chemistry, and are common supporting
ligands in transition metal catalysis. An attraction of tertiary phosphines is the ability to tune their electronic
and steric properties. While trialkylphosphines are some of the most electron-donating examples, aryl
phosphines tend to be more easily handled and are sufficiently strong donors for many applications.
Furthermore, phenyl/aryl groups on phosphine ligands in metal complexes can play a major role in the driving
the supramolecular order.1
Large polycyclic aromatic hydrocarbons have gained considerable interest because of their electronic and
optical properties, and the strong π-interactions that direct their assembly into columnar stacks.2 One such
nanographene is hexa-peri-hexabenzocoronene (HBC), consisting of 42 carbon atoms in 13 fused rings; the hexagonal geometry and stability comparable to benzene has led to HBC being described as ‘superbenzene’ (see figure). As part of our research into nanographene-based ligands, we have synthesized a series of
‘superphenylphosphines’.3 The coordination of these phosphines to several different metals has been investigated, along with the role the HBC fragment plays on coordination geometry and driving assembly in the crystalline phase.
[1] I. Dance, M. Scudder, CrystEngComm 2009, 11, 2233.
[2] K. Müllen, ACS Nano. 2014, 8, 6531.
[3] J. N. Smith, J. M. Hook and N. T. Lucas, J. Am. Chem. Soc. 2018, 140, 1131.
119
POLYNUCLEAR CHEMISTRY OF CSe AND CTe
Benjamin J. Frogley, Chee Seng Onn, Lachlan J. Watson and Anthony F. Hill* Research School of Chemistry, Australian National University, Canberra, ACT, Australia
Email: [email protected]
The coordinative activation of carbon monoxide by transition metals underpins numerous industrially
significant processes. In the case of heterogeneous catalysts (e.g., the Fischer Tropsch synthesis) the intimate
details of this activation may be obscure and rely upon insights provided by the spectroscopic and computational
interogation of molecular model complexes.
The heavier carbon monochalcogenides (CA: A = S, Se, Te), whilst not independently isolable species,
offer a rich organometallic chemistry, once installed, because each of the classical components of synergic
bonding (-donation, -retrodonation) are significantly enhanced relative to CO. This in turn makes new
modification processes and coordination modes accessible.
This presentation will survey recently published1 and unpublished results from our group concerned
with the synthesis, characterisation and reactivity of mononuclear selenocarbonyl (LnMCSe) and
tellurocarbonyl (LnMCTe) complexes as well as related unsaturated carbon chalcogenide species. Particular
emphasis will be placed on bi- and poly-metallic assemblies including unprecedented and variable (‘switching’)
modes of coordination and activation.
1. B. J. Frogley, A. F. Hill, L. J. Watson, Dalton Trans., 2019, 48, 12598. (b) B. J. Frogley, A. F. Hill, C.
S. Onn, Dalton Trans., 2019, 48, 11715. (c) B. J. Frogley, T. L. Genet, A. F. Hill, C. S. Onn, Dalton
Trans., 2019, 48, 7632. (d) I. A. Cade, A. F. Hill, C. M. A. McQueen, Dalton Trans., 2019, 48, 2000.
(e) B. J. Frogley, A. F. Hill, R. A. Manzano, M. Sharma, Chem. Commun., 2018, 54, 1702. (f) B. F.
Frogley, A. F.Hill, Angew. Chem., Int. Ed., 2019, 58, 8044. (g) B. J. Frogley, A. F. Hill, Angew. Chem.,
Int. Ed., 2019, 58, DOI: 10.1002/anie.201909333. (h) B. J. Frogley, A. F. Hill and L. J. Watson, Chem.
Commun., 2019, 55, DOI: 10.1039/c9c07757j
120
Thursday 19th
December
Session 2
121
SOLAR POWERED ENZYMES TO DRIVE THE RENEWABLE HYDROGEN ECONOMY
Trevor D. Rapson,1* Tara D. Sutherland,1 HyungKuk Ju,2 Sarb Giddey2 and Craig C. Wood1
1 CSIRO, Black Mountain, 2601, Canberra, ACT, Australia 2 CSIRO, Clayton, 3169, VIC, Australia
Email: [email protected]
Hydrogen is an attractive clean fuel source, given its high energy density, and represents an opportunity for
Australia to export its renewable energy.1 Water electrolysis can allow the production of H2 without the use of fossil fuels, if renewable energy, such as solar, is used to power the reaction. To allow the production of large
quantities of H2, efficient hydrogen evolution reaction (HER) catalysts are required. Currently the state-of-the- art catalysts are based on platinum, however the scarcity and expense of platinum is driving the need for non- platinum HER catalysts to be developed.
Hydrogenase enzymes produce H2 from aqueous solutions with high turnover frequencies (10,000 s-1) using
first row transition metals, iron and/or nickel, with zero overpotential. Unfortunately, these enzymes do not have
sufficient stability outside of their biological context to be useful in industrial applications. To produce robust
catalysts that incorporate the advantages of biological systems and are suitable for industrial applications we
have pursued an approach to produce solid-state metalloprotein materials using a recombinant silk protein from
honeybees.2 Here, we report a bioinorganic HER catalyst using cobalt protoporphyrin IX. Through protein
engineering we modified the axial coordination of the porphyrin to enhance its catalytic properties. We used the
engineered bioinorganic catalyst to fabricate a water electrolysis cell, demonstrating the robustness of the
biologically derived material.
To allow the export of H2 it must first be converted to ammonia which is easy and safe to transport, and the
infrastructure for this is already in existence.3 Nitrogen-fixing bacteria are able to produce ammonia from N2
and protons at room temperature and atmospheric pressure using nitrogenase. These enzymes can be light-
driven and represent a promising alternative to the energy intensive Haber-Bosch process.4 In this talk we will outline our progress in developing a solar powered nitrogenase system suitable for the large-scale production of ammonia.
Figure adapted from ref 5.
(1) https://www.abc.net.au/news/2017-05-11/hydrogen-breakthrough-could-fuel-renewable-energy-export-
boom/8518916 (accessed Aug 9, 2019).
(2) Rapson, T. D.; Kusuoka, R.; Butcher, J.; Musameh, M.; Dunn, C. J.; Church, J. S.; Warden, A. C.;
Blanford, C. F.; Nakamura, N.; Sutherland, T. D. J. Mater. Chem. A 2017, 5, 10236–10243.
(3) Giddey, S.; Badwal, S. P. S.; Munnings, C.; Dolan, M. ACS Sustain. Chem. Eng. 2017, 5, 10231–10239.
(4) Brown, K.A. et al. Science 2016, 352, 448- 449.
(5) https://www.renewablehydrogen.com.au/copy-of-about-rh2-and-araem-our-vis-1 (accessed Sept 18,
2019).
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SITE-SPECIFIC INCORPORATION OF METAL RADIONUCLIDES INTO ANTIBODIES FOR DIAGNOSTIC IMAGING
Stacey. E. Rudd*1, Lesley Pearce2, Charlotte Williams2, Timothy E. Adams2, Peter Roselt3a, Jessica K. Van Zuylekom3a, 3b, Carleen Cullinane3a,3b, Rodney J Hicks3b, 3c and Paul S. Donnelly1
1School of Chemistry, University of Melbourne and Bio21 Molecular Science & Biotechnology Institute, Vic,
Australia 2 Biomedical Manufacturing, Commonwealth Scientific and Industrial Research Organization, Vic, Australia
3a Research Division, Peter MacCallum Cancer Centre, Vic, Australia 3bThe Sir Peter MacCallum Department of Oncology, Vic, Australia
3cCentre for Cancer Imaging, Peter MacCallum Cancer Centre, Vic, Australia Email: [email protected]
Figure 1. Structures of bifunctional chelators used for site-specific enzyme-mediated attachment to an antibody fragment, and a MIP PET/CT of an A431 tumour-bearing mouse imaged 3 h post administration of
the imaging agent [89Zr]ZrDFOSqPEGGly-F(ab’)528.
Positron emission tomography (PET) is a medical imaging technique, particularly useful for the detection and
diagnosis of cancers. Antibodies which specifically bind to over-expressed receptors in cancer cells can be used
to target a positron-emitting radionuclide to tumours. PET imaging with radiolabelled antibodies can identify
patients most likely to respond to immunotherapy.
Antibodies have long pharmacokinetic half-lives and take days to accumulate in the target site so they must be
labelled with radionuclides with relatively long radioactive half-lives such as copper-64 and zirconium-89.
Preparation of antibody conjugates suitable for metal-based PET can be a challenging task. An appropriate
bifunctional chelator that can incorporate a metal radionuclide must be attached to amino acid side chains within
the protein, although this usually gives a mixture of products with varying degrees of attachments. An example
using the monoclonal antibody cetuximab will be presented.
To circumvent the issue of indiscriminate conjugation, we have prepared site-specifically modified conjugates
of an EGFR-targeting antibody fragment (Fab528). These F(ab’) conjugates were prepared via an enzyme-
mediated coupling using the bacterial peptidase Sortase A. The conjugates were radiolabelled with either
positron-emitting copper-64 and zirconium-89. The tumour imaging potential of the new conjugates was
investigated in tumour-xenograft mice models (Figure 1).
123
NEW REACTIONS AND NEW INTERMEDIATES IN CYSTEINE DIOXYGENASE
Guy N. L. Jameson1* 1School of Chemistry | Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne,
Parkville, VIC 3010, Australia Email: [email protected]
Cysteine dioxygenase catalyses the oxidation of cysteine to cysteine sulfinate through the addition of molecular
oxygen. The catalytic cycle occurs at a ferrous iron atom coordinated via three histidine residues. Crystal
structures, spectroscopic studies and model complexes show cysteine binding via the thiol and amine to leave
the sixth coordination site, the dioxygen binding site, partially occupied by a water molecule.1 Reactions under
single turnover conditions have revealed an initial intermediate2 that is possibly an iron-superoxo.3 Similar
initial intermediates are formed in the catalytic cycle of IPNS4 during penicillin biosynthesis but in this case the
superoxo species carries out hydrogen atom abstraction rather than sulfur oxygenation. We are using a combined
protein and small molecule model approach to understand the mechanism of cysteine dioxygenase and
understand how reactivity is controlled. We will describe in this presentation the current state of our research.
1 J.B. Gordon, J.P. McGale, J.R. Prendergast, Z. Shirani-Sarmazeh, M. A. Siegler, G.N.L. Jameson, D.P. Goldberg J. Am. Chem. Soc. 2018, 140, 14807.
2 E.P. Tchesnokov, A.S. Faponle, C.G. Davies, M.G. Quesne, R. Turner, M. Fellner, R.J. Souness, S.M. Wilbanks, S.P. de Visser, G.N.L. Jameson Chem. Commun. 2016, 52, 8814.
3 M.N. Blakely, M.A. Dedushko, P.C.Y. Poon, G. Villar-Acevedo, J. Kovacs J. Am. Chem. Soc. 2019, 141, 1867. 4 E.Y. Tamanaha, B. Zhang, Y. Guo, W-C. Chang, E.W. Barr, G. Xing, J. St Clair, S. Ye, F. Neese, J.M.
Bollinger Jr., C. Krebs, J. Am. Chem. Soc. 2016, 138, 8862.
124
POROUS COORDINATION POLYMERS OF ALKYLAMINE LIGANDS
Stuart R. Batten1*, David R. Turner1, Ali Chahine1, Chris S. Hawes1, Jamie Hicks1 and Adrian J.
Emerson1
1School of Chemistry, 19 Rainforest Walk, Monash University 3800, Australia Email: [email protected]
Figure 1. Example alkylamine ligands and porous coordination polymer.
We have been investigating the use of alkylamine ligands in the synthesis of porous coordination polymers.1
The amine groups form part of the ligand backbones, and are designed to improve the selectivity of carbon
dioxide capture over other gases. More than 50 new ligands have been made, and more than a dozen porous
frameworks identified and tested. The ligands investigated fall into three different categories: (i)
azamacrocycles, (ii) piperazines, and (iii) linear alkyl amines. Good carbon dioxide capacities and selectivities
have been observed, as well as high stability to moisture, unusual structural transformations and interesting
structural features. Related work has also looked at the use of these materials for the separation of complex
aromatic hydrocarbon mixtures, and the incorporation of metal carbonyl species into the ligand backbones, with
a view to creating new heterogeneous catalysts.
1. A. J. Emerson, A. Chahine, S. R. Batten, D. R. Turner. Coord. Chem. Rev. 2018, 365, 1-22.
125
PRESSURE-INDUCED STRUCTURAL TRANSFORMATIONS IN THE METAL GUANIDINIUM FORMATES
Zhengqiang Yang, Guanqun Cai, Shurong Yuan and Anthony E. Phillips* School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, United Kingdom
Email: [email protected]
The hybrid perovskites are coordination frameworks with the same topology as the inorganic perovskites, but
with cubic “A-site” interstices large enough to incorporate polyatomic organic cations.1 As a result, these materials’ properties are driven by subtly different chemistry. First, polyatomic cations have a more complex shape than spherically symmetrical atomic ions, and thus may have intrinsic dipole or indeed higher-order
multipole moments.2 Second, the nature of the interactions between organic ions and the surrounding framework
is different to the inorganic case; in particular, for organic ions, hydrogen bonding will play an important role.3
Third, turning from the encapsulated ions to the framework itself, larger frameworks are more flexible than smaller ones, both in the dynamic sense in that they are able to change their shape to accommodate changes in temperature, pressure, or applied field, and in the static sense that a greater variety of crystalline phases is often
known.4 Like the inorganic perovskites, these materials exhibit many different phases, including structures with potentially exploitable functionality. However, their phase transformations under pressure are more complex
and less well understood.5
We will discuss the structural evolution of the hybrid perovskite series of metal guanidinium formates,
C(NH2)3[M(HCO2)3], under pressure, using single-crystal X-ray and powder neutron diffraction supported by DFT simulation. In the formate perovskites – in contrast to their inorganic counterparts – the longer formate linker cations decouple the coordination geometry around individual ions from the overall network topology. As a result, the cubic topology becomes rather more robust, in one recently reported case even recoverable from
pressure-induced amorphisation.6 We present a series of structural transformations that preserve the perovskite topology while exploring a range of crystalline symmetries and coordination geometries, and show that the
behaviour of these materials under pressure can be rationalised in terms of host-guest hydrogen bonding.7 Our results demonstrate more generally that identifying suitable host-guest hydrogen-bonding geometries may provide a route to engineering hybrid perovskite phases with desirable crystal structures.
1Li, W. et al. Nat. Rev. Mater. 2017, 2, 201699; Kieslich, G. & Goodwin, A. L. Mater. Horiz. 2017, 4, 362. 2Evans, N. L. et al. J. Am. Chem. Soc. 2016, 138, 9393. 3Shang, R. et al. Chem. Eur. J. 2014, 20, 15872; Chen, S. et al. Inorg. Chem. Front. 2014, 1, 83; Shang, R. et al.
Angew. Chem. Int. Ed. 2016, 55, 2097; Kieslich, G. et al. Chem. Mater. 2016, 28, 312. 4Xu, W.-J. et al. CrystEngComm 2016, 18, 7915. 5Collings, I. E. et al. ChemPhysChem 2016, 17, 3369–3372; Collings, I. E. et al. CrystEngComm 2016, 18,
8849–8857; Feng, G. et al. Dalton Trans. 2016, 45, 4303. 6Chitnis, A. V. et al. Dalton Trans. 2018, 47, 12993. 7Yang, Z. et al. Phil. Trans. Royal Soc. A 2019, 377, 20180277.
126
THE EFFECT OF PRESSURE, GUEST UPTAKE AND STRUCTURAL FLEXIBILITY ON POROUS MATERIALS
S. Moggach1* 1School of Molecular Sciences and Centre for Microscopy, Characterisation and Analysis (CMCA), The
University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, AUSTRALIA
Email: [email protected]
In recent years the development of new methods of storing, trapping or separating light gases, such as CO2, CH4
and CO has become of outmost importance from an environmental and energetic viewpoint. Porous materials
such as zeolites and porous organic polymers have long been considered good candidates for this purpose. More
recently, metal organic frameworks (MOFs) have attracted further interest with many aspects of their functional
and mechanical properties investigated. The porous channels found in MOFs are ideal for the uptake of guests
of different shapes and sizes, and with careful design they can show high selectivity for particular species from
a mixture. Adsorption properties of MOFs have been thoroughly studied, however obtaining in depth
‘structural’ insight into the adsorption/desorption mechanism is not so common place.
Over the last 6 years, we have been using high-pressure crystallographic techniques to explore the uptake of
guest species in the pores of MOFs, and explore their structural stability to pressure. We do this, by taking
advantage of the fact that the small molecules that encompass the pressure transmitting fluids used frequently
in high-pressure crystallographic studies, can penetrate the pores on increasing pressure. This has revealed
unexpected flexibility, explain unusual adsorption phenomena under milder pressures, and increase reactivity
in MOFs. Here, we will give an overview of the effect of high-pressure on micro and nanoporous materials,
and in-particular, highlight some recent work on molecular nanoporous materials.
1. Bezzu, C.G., Burt, L.A., McMonagle, C.J. et al. Highly stable fullerene-based porous molecular
crystals with open metal sites. Nat. Mater. 2019, 18, 740.
127
ZAPPING AND SMASHING LIGHT EMITTING LANTHANOID COMPLEXES
Lee Cameron1, Harry Kirkland1, Massimiliano Massi1 and Mark I. Ogden*1
1School of Molecular and Life Sciences, Curtin University, Western Australia Email: [email protected]
1 2
Figure: Mononuclear neutral (1) and anionic (2) lanthanoid complexes of tribenzoylmethane.
We have been studying -triketonates such as tribenzoylmethane (tbm) as a simple extension of classic - diketonate ligands. When these ligands are made to react with lanthanoid cations in the presence of alkali metal hydroxides, tetranuclear lanthanoid/alkali metal coordination clusters with remarkable light emitting properties
are formed.1 Using triethylamine as the base results in the formation of mononuclear neutral (1),2 or anionic (2)
lanthanoid complexes, as is typically found with analogous -diketonates. Recent results probing the influence of co-ligands in the neutral complexes on photophysical properties will be discussed. We have also been investigating fractoluminescence of anionic complexes of di- and tri-ketonates. The europium diketonate
complexes are classic examples of strongly fractoluminescent complexes,3 and our initial efforts to systematically measure fractoluminescent emission from such complexes will be described.
1. B. L. Reid, S. Stagni, J. M. Malicka, M. Cocchi, G. S. Hanan, M. I. Ogden and M. Massi, Chem. Commun.,
2014, 50, 11580; B. L. Reid, S. Stagni, J. M. Malicka, M. Cocchi, A. N. Sobolev, B. W. Skelton, E. G.
Moore, G. S. Hanan, M. I. Ogden, and M. Massi, Chem. Eur. J., 2015, 21, 18354; L. Abad Galán, B. L. Reid,
S. Stagni, A. N. Sobolev, B. W. Skelton, M. Cocchi, J. M. Malicka, E. Zysman-Colman, E. G. Moore, M. I. Ogden, and M. Massi, Inorg. Chem., 2017, 56, 8975.
2. L. Abad Galán, B. L. Reid, S. Stagni, A. N. Sobolev, B. W. Skelton, E. G. Moore, G. S. Hanan, E. Zysman-
Colman, M. I. Ogden, and M. Massi, Dalton Trans., 2018, 47, 7956; L. Abad Galán, S. Wada, L. Cameron,
A. N. Sobolev, Y. Hasegawa, E. Zysman-Colman, M. I. Ogden, and M. Massi, Dalton Trans., 2019, 48,
3768.
3. C. R. Hurt, N. McAvoy, S. Bjorklund and N. Filipescu, Nature, 1966, 212, 179; R. S. Fontenot, K. N. Bhat,
W. A. Hollerman, M. D. Aggarwal and K. M. Nguyen, CrystEngComm, 2012, 14, 1382.
128
6
NEW EXAMPLES OF LANTHANIDE CONTAINING SINGLE MOLECULE TOROICS (SMTS) AND OF D-F
HETEROMETALLICS
Keith S. Murray,*a Stuart K. Langley,b Kuduva R. Vignesh,c, Gopalan Rajaraman,d Tulika Gupta,e
Ivana Borilovic,a Wasinee Phonsri,a Craig M. Forsyth.a
a Monash University, b Manchester Metropolitan University, c Institute of Molecular Science, Okazaki, d IITB Mumbai, e Banaras Hindu University
Email:[email protected]
Single molecule toroics (SMTs) are a sub topic of single molecule magnets (SMMs). They generally consist of molecular rings (triangles, squares, hexagons) of lanthanide(III) ions, particularly of dysprosium, but there
are recent examples of non-ring systems.1 The pioneering work by Powell, Chibotaru, et al. on µ3-OH bridged
Dy3 triangles revealed the requisite molecular geometry, the directions of the magnetic moments on each Dy,
the nature of magnetisation vs. field plots (often S-shaped) and relevant theory.2 From a more applied perspective, SMTs offer possible uses in quantum information processing, high-density data storage and as nanoscale devices such as molecular spin valves and spin transistors.
Two classes of SMTs will be described. The first involve triangles of Tb, Dy, Ho of type
[LnIII3(OH)(teaH2)3(paa)3]Cl2, where teaH3 = triethanolamine, paaH = N-(2-pyridyl)-acetoacetamide and a
new Dy6 hexagon [DyIII (pdeaH)6(NO3)6] where pdeaH3 = = 3-[bis(2-hydroxyethyl)amino]propan-1-ol].3 (see Figure) The second class are “double triangles” of type [DyIII
6MIII(OH)8(o-tol)12(MeOH)5(NO3)]∙4MeOH, where MIII
= Cr,4 Mn, Fe, Co, Al, o-tol = o-toluate, in which the MIII ion bridges the two Dy3 triangles in a MO6
coordination environment. The parent CrIII system showed a rare ferrotoroidal arrangement of the toroidal
moments on each triangle. Comparisons will be made to the new MIII-bridged materials which include
paramagnetic MnIII and FeIII and diamagnetic CoIII and p-block AlIII.
Acknowledgments. We thank Professor W. Wernsdorfer, Dr M. Damjanovic, Dr A. Soncini and Mr J.
Crabtree for experimental and theoretical input.
1. X.-L Li, J. Tang, Dalton Trans. 2019, in press.2. (a) J. Tang, I. Hewitt, N. T. Madhu, G. Chastanet, W. Wernsdorfer, C. E. Anson, C. Benelli, R.
Sessoli, A. K. Powell, Angew. Chem. Int. Ed., 2006, 45, 1729-1733.
(b) L. F. Chibotaru, L. Ungur, A. Soncini, Angew. Chem. Int. Ed., 2008, 47, 4126-4129.
3. S. K. Langley, K. R. Vignesh, T. Gupta, C. J. Gartshore, G. Rajaraman, C. M. Forsyth, K. S. Murray,
Dalton Trans. 2019, in press.
4. K. R. Vignesh, A. Soncini, S. K. Langley, W. Wernsdorfer, K. S. Murray, G. Rajaraman, Nat.
Commun., 2017, 8, 1023.
129
LUMINESCENT LANTHANIDE-BASED COMPLEXES AND THEIR APPLICATION TO THE DETECTION OF
BIOLOGICALLY AND ENVIRONMENTALLY RELEVANT SPECIES
Kellie L. Tuck School of Chemistry, Monash University, Victoria 3800, Australia
Email: [email protected]
As part of a quest to detect biologically and environmentally relevant species, we have been interested in the
synthesis and analysis of luminescent lanthanide-based complexes.1-4 Lanthanides themselves are weakly
luminescent, however when paired with an appropriate sensitiser (antenna), energy transfer from an energy- harvesting moiety to the lanthanide occurs. The resulting long-lived luminescence allows for time-gated signal detection thus eliminating interference from the short-lived fluorescence emitted by biological or environmental matter.
Two recent examples from our group are; luminescent lanthanide-based chemosensors for the detection of
hydrogen sulfide (HS-) and guanosine monophosphate (GMP) (Figure 1a and b respectively).1,3 For the detection
of hydrogen sulfide, the complex features a Cu2+-binding DPA group and a pyridinyl triazole antenna. The
luminescence of the complex is quenched in the presence of Cu2+ ions and the addition of hydrogen sulfide
restores the luminescent signal, due to the precipitation of Cu2+ as copper sulfide. For the detection of GMP, the inclusion of zinc(II)-cyclen moieties allow coordinative interactions of the complex with the phosphate groups of GMP. On the binding of GMP a luminescent signal is observed, which is not observed in the presence of cyclic GMP. Thus, this complex has been utilised to monitor the conversion of cGMP to GMP by a phosphodiesterase enzyme, in real time, using time-gated luminescence. Our recent findings of an alternative lanthanide-based complex for the detection of hydrogen sulfide will also be disclosed.
This presentation will describe the synthesis of each of the complexes, and the challenges faced along the way.
Additionally, their photophysical properties, and the host-guest supramolecular chemistry that allows the
quantitative detection of biologically and/or environmentally relevant species will be discussed.
Figure 1: a) Schematic representation of the HS- sensing principle. (b) Schematic representation of the GMP sensing principle.
1. M. L. Aulsebrook, S. Biswas, F. M. Leaver, M. R. Grace, B. Graham, A. M. Barrios, K. L. Tuck. Chem.
Commun. 2017, 53, 4911.
2. M. L. Aulsebrook, M. R. Grace, B. Graham, K. L. Tuck. Coord. Chem. Rev. 2018, 375, 191-220.
3. M. L. Aulsebrook, M. Starck, M. R. Grace, B. Graham, P. Thordarson, R. Pal, K. L. Tuck. Inorg. Chem.
2019, 58, 495-505.4. M. R. Winnett, P. Mini, M. R. Grace, K. L. Tuck. Inorg. Chem. 2019 DOI: 10.1021/
acs.inorgchem.9b01771.
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