international workshop - materials...

INTERNATIONAL WORKSHOP

ADVANCED MATERIALS

21st-25th July 2019

St. St. Constantine and Helena

Varna, Bulgaria

BOOK OF ABSTRACTS

PROGRAM

LIST OF PARTICIPANTS

“Materials Networking” project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 692146.

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SCOPE AND OBJECTIVES

The Workshop “Advanced Materials” is organized by the Faculty of Chemistry and

Pharmacy, University of Sofia within the H2020-TWINN-2015 Project “Materials Networking”. The workshop aims at gathering together scientists from the partner

organizations working in the area of advanced materials and related topics and thus

identifying mutual areas of interests, exchange of knowledge and finding fields for following

collaboration with the partner organizations.

Partner Organizations:

Department of Materials Science & Metallurgy, University of Cambridge, UK

Max-Planck Institute of Polymer Research, Mainz, DE

Faculty of Chemistry, University of Barcelona, ES


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Horizon 2020 Project “Materials Networking” “Advanced Materials” Workshop

21 – 25 July 2019, St. St. Constantine and Helena, Varna, Bulgaria

ORGANIZERS

Faculty of Chemistry and Pharmacy, University of Sofia

Georgi Vayssilov

Rositca Nikolova

Anela Ivanova

Tony Spassov

Roumen Tsekov

Elena Vassileva


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PREFACE

The main objective of the TWINNING project is enhancement the scientific and technological capacity of

the Faculty of Chemistry and Pharmacy at Sofia University (FCP-SU) and raising the research profile of the

Faculty and its staff in the field of advanced functional materials via networking with three World-wide

leading institutions – Department of Materials Science & Metallurgy, University of Cambridge, Max-Plank

Institute of Polymer Research and Faculty of Chemistry, University of Barcelona. Faculty of Chemistry and

Pharmacy at SU is a leading research centre in functional materials in Bulgaria and its networking

and collaboration with global leaders in this research field will help in developing its potential to become

European-wide known centre with increasing research and innovation contributions and achievements. Such

achievements will increase the participation of the teams from FCP-SU in European and international

projects and will promote higher performance of other research institutions in Bulgaria. Based on the

expertise and achievements of the research groups in FCP-SU, the present project will contribute to two

of the priority areas of the Bulgaria’s Smart Specialization Strategy with relevant thematic priorities

“Materials for clean energy and environment protection” and “Materials with pharmaceutical and medical

applications”.


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Program Sunday, 21st July

17:30 PL1

Lindsay Greer “Metallic Glasses: a range of states offering exceptional mechanical properties"

18:10 18:30 OP1

Jaume Garcia-Amorós “Mechanofluorescent liquid-crystalline elastomers”

19:00 Welcome Party Monday, 22nd July

10:00 Opening ceremony Georgi Vayssilov – project coordinator Milena Damyanova – Director, Directorate “Science”, Ministry of Education and Science

10:20 PL2

Pere Alemany “First principles modelling of radiation damage: calculation of the electronic stopping power for polymers through non-adiabatic molecular dynamics simulations”

11:00 OP2

Petko Petkov “Computational modeling of H/H+ migration in porous layered materials”

11:20 OP3

Kai Steffen Exner “Computational assessment of the performance of a drug-delivery system component”

11:40 OP4

Albert Figuerola “Preparation and applications of colloidal Au-Ag-chalcogen-based ternary nanocrystals with tunable composition”

12:00 SO1

Chaojian Chen “Polymer-grafted gold nanoflowers with temperature-controlled catalytic features by combining ARGET ATRP and metal reduction in one pot”

12:10 OP5

Nevena Petkova-Yankova “Synthesis and chemical properties of 3-phosphonocoumarins as precursors for bioactive compounds”

12:30 Lunch 16:00 KN1

Ruth Cameron “Ice-templated and charge-deposited structures for regenerative medicine”

16:30 OP6

Kaloian Koynov “Fluorescence correlation spectroscopy studies of drug nanocarriers in flowing blood”

16:50 OP7

Petar Petrov “Super-macroporous polysaccharide cryogels: Synthesis and application as drug carriers and cell scaffolds”

17:10 Coffee Break 17:30 OP8

Christopher Synatschke “Neural cell scaffolds and biohybrid hydrogels from peptide nanofibers”

17:50 OP9

Konstantin Balashev “The neurotoxin VIPOXIN and its action on model membrane systems and living cells”

18:10 OP10

Todor Dudev “How Pb2+ binds and modulates properties of Ca2+ - signaling proteins”

18:30 18:50 OP11

Stanislava Yordanova “Spectral characterization of poly(propylene imine) metallodendrimers in solution and onto cotton fabrics and their antimicrobial and antibiofilm activity”

19:00 Dinner


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Tuesday, 23th July

09:00 KN2

Vasant Kumar “The role of 2D-like materials in batteries”

09:30 OP12

Tony Spassov “LiMnPO4-olivine deposited on microporous alloy as additive-free electrodes for lithium ion batteries”

09:50 SO2

Hristo Rasheev “Solvation-desolvation thermodynamics in mixed alkaline-ion batteries”

10:00 OP13

Alia Tadjer “Singlet fission - a magic bullet for organic photovoltaics”

10:20 SO3

Roger Bujaldón “Extending the carbazole core towards enhanced organic semiconductors”

10:30 Coffee Break 10:50 KN3

Zoe Barber “The control of thin film structures, and applications in materials science”

11:20 OP14

Slavka Tcholakova “Efficient methods for preparation of emulsions and nanoemulsions”

11:40 OP15

Zhulieta Valkova “Multilayer formation in Self-Shaping emulsion droplets”

12:00 SO4

Fatmegyul Mustan “Surface and foam properties of nonionic surfactant solutions at high sugar concentration”

12:10 12:20 SO5

Nikolay Grozev “Physico-chemical properties of L-Asp based gemini surfactants”

12:30 Lunch

16:00 Steering Committee meeting

18:00 OP16

Irina Karadjova “Speciation of Cr, Mn and Hg in environmental samples by using composite sorbents based on noble nanoparticles embedded in thin films”

18:20 OP17

Ivo Ivanov, Silviya Stoykova “Common tea for smoking? Trends and cases in Bulgaria”

18:40 OP18

Valentina Lyubomirova “ICP-MS characterization of Bulgarian bottled mineral and spring waters”

19:00 Dinner

Wednesday, 24th July

09:00 KN4

Chris Pickard “Random explorations of material structure space”

09:30 OP19

Stanislav Baluschev “Local temperature and oxygen sensing in water environment using annihilation upconversion materials embedded in wax-matrices”

09:50 SO6

Nikoleta Kircheva “A DFT/PCM study of the complexation between Ga3+ and ribonucleotide reductase substrates”

10:00 SO7

Zhihong Ye “Fe-based MOFs as efficient catalysts for the degradation of emerging contaminants in urban wastewater”

10:10 OP20

Jordi Cirera “Multiscale modeling of spin-crossover phenomena in molecular materials”

10:30

Coffee Break


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10:50 OP21

Stoyan Yordanov “Evaluation of newly developed dye tags for proteins characterization and detection by Fluorescence Correlation Spectroscopy”

11:10 OP22

Giorgio Divitini “Electron Microscopy and Multivariate Analysis for dynamical characterisation of perovskite solar cells”

11:30 OP23

Martin Tsvetkov “Luminescence properties of Gd1.97-xSmxTb0.03Mo3O12 for potential LED applications”

11:50 SO8

Marc Figueras Valls “Correcting Flaws in the assignment of nitrogen chemical environments in N-doped graphene”

12:00 SO9

Anabel Jurado “First principles evaluation of the initial oxidation of transition metal surfaces”

12:30 Lunch

16:00 OP24

Stefan Tsakovski “Assessment of the Bulgarian wastewater treatment plants impact on the receiving water bodies”

16:20 OP25

Theodor Gurkov “Interfacial layers of volatile surfactants: adsorption and kinetics of evaporation”

16:40 OP26

Spas Kolev “Microfluidic fabrication of micro polymer inclusion beads (µPIBs). Application to the recovery of gold from electronic scrap”

17:00 Coffee break 17:20 OP27

Rumen Tomov “Inkjet printing of direct carbon solid oxide fuel cell”

17:40 OP28

Mihail Georgiev “Bicontinuous phases from mixed surfactant solutions with enhanced solubilization capacity and their potential applications”

18:00 OP29

Rumen Lyapchev “NHC-ligands: Imidazopyridine-3-ylidenes versus Imidazoquinoline-1-ylidenes”

18:20 18:30 SO10

Konstans Ruseva “Triple stimuli-responsive interpenetrating polymer network of poly(carboxybetaine methacrylate)/poly(sulfobetaine methacrylate)”

19:00 Dinner

Thursday, 25th July

09:30 OP30

Milen Bogdanov “Ionic liquids as alternative solvents in the sample treatment for determination of biologically active compounds in plants”

09:50 OP31

Angel Morales Garcia “Stability or photoactivity? Properties of realistic TiO2 nanoparticles”

10:10 OP32

Tsveta Sarafska “Inclusion complexes of naproxen in amorphous gamma cyclodextrin”

10:30 SO11

Mengxi Lin “Synthesis and characterization of nanostructured Pt-Ag-based chalcogenide semiconductors”

10:40 SO12

Raul Morales “Twodimensional Transition Metal Carbides/nitrides (MXenes) as potential catalysts for CO2 conversion to CO”

10:50 SO13

Joan Mariñoso Guiu “How to accurately model the IR spectra of nanosilicates”

12:30 Lunch


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CONTENTS

PLENARY LECTURES

PL1 Lindsay Greer Metallic Glasses: a range of states offering exceptional mechanical properties

14

PL2 Pere Alemany First principles modelling of radiation damage: calculation of the electronic

stopping power for polymers through non-adiabatic molecular dynamics

simulations

15

KEYNOTE LECTURES

KN1 Ruth E. Cameron Ice-templated and charge-deposited structures for regenerative medicine

17

KN2 R Vasant Kumar The role of 2D-like materials in batteries

18

KN3 Zoe Barber The control of thin film structures, and applications in materials science

19

KN4 Chris J Pickard Random explorations of material structure space

20

ORAL PRESENTATIONS

OP 1 Jaume Garcia-Amorós, Dolores Velasco

Mechanofluorescent liquid-crystalline elastomers

22

OP 2 Petko Petkov, Yun An, Agnieszka Kuc, Thomas Heine

Computational modeling of H/H+ migration in porous layered materials

23

OP 3 Kai S. Exner, Anela Ivanova

Computational Assessment of the Performance of a Drug-Delivery System

Component

24

OP 4 Albert Figuerola, Mariona Dalmases, Pau Torruella, Javier Blanco-Portals, Sònia

Estradé, Francesca Peiró

Colloidal noble metal-based ternary chalcogenide nanocrystals with tunable

composition

25


9

OP 5 Ana I. Koleva, Nevena I. Petkova-Yankova, Rositca D. Nikolova

Synthesis and chemical properties of 3-phosphonocoumarins as precursors for

bioactive compounds

26

OP 6 Kaloian Koynov, Jennifer Schultze, Inka Negwer, Stoyan Yordanov, Hans-

Jürgen Butt

Fluorescence correlation spectroscopy studies of drug nanocarriers in flowing

blood

27

OP 7 Petar D. Petrov, Yavor Danov, Denitsa Momekova

Super-macroporous polysaccharide cryogels: Synthesis and application as drug

carriers and cell scaffolds

28

OP 8 Christopher V. Synatschke, Thomas Mack, Jasmina Gacanin, Adriana Sobota,

Tanja Weil

Neural cell scaffolds and biohybrid hydrogels from peptide nanofibers

29

OP 9 Kristina Mirchev, Svetla Petrova, Nikolai Grozev, Tzvetanka Ivanova, Ivan

Panaiotov, Konstantin Balashev

The neurotoxin VIPOXIN and its action on model membrane systems and living

cells

30

OP10 Todor Dudev, Cedric Grauffel, Carmay Lim

How Pb2+ binds and modulates properties of Ca2+- signaling proteins

31

OP11 Stanislava Yordanova, Stanimir Stoyanov, Desislava Staneva, Ivo Grabchev

Spectral characterization of poly(propylene imine) metallodendrimers in solution

and onto cotton fabrics and their antimicrobial and antibiofilm activity

32

OP12 L. Mihaylov, T. Boyadzhieva, V. Kumar, R. Tomov, V. Koleva, R. Stoyanova,

T.Spassov

LiMnPO4-olivine deposited on microporous alloy as additive-free electrodes for

lithium ion batteries

33

OP13 Joanna Stoycheva, Julia Romanova, Artur Nenov, Alia Tadjer

Singlet fission - a magic bullet for organic photovoltaics

34

OP14 Slavka Tcholakova, Nikolai Denkov

Efficient methods for preparation of emulsions and nanoemulsions

35

OP15 Zh. Valkova, D. Cholakova, S. Tcholakova, N. Denkov, S. K. Smoukov

Multilayer formation in Self-Shaping emulsion droplets

36


10

OP16 Penka Vassileva, Irina Karadjova, Tanya Yordanova, Elisaveta Mladenova

Speciation of Cr, Mn and Hg in environmental samples by using composite

sorbents based on noble nanoparticles embedded in thin films

37

OP17 Ivo D. Ivanov, Silviya Stoykova, Nikola Burdzhiev, Ivayla Pantcheva,

Vasil N. Atanasov

Common tea for smoking? Trends and cases in Bulgaria

38

OP18 Valentina Lyubomirova, Veronika Mihaylova and Rumyana Djingova

ICP-MS characterization of Bulgarian bottled mineral and spring waters

39

OP19 R. Dimitrova, S. Baluschev, K. Landfester

Local temperature and oxygen sensing in water environment using annihilation

upconversion materials embedded in wax-matrices

40

OP20 Jordi Cirera

Multiscale modeling of spin-crossover phenomena in molecular materials

41

OP21 Stoyan Yordanov, Aleksey Vasilev, Martin Drucker, Hans-Juergen-Butt,

Kaloian Koynov

Evaluation of newly developed dye tags for proteins characterization and

detection by Fluorescence Correlation Spectroscopy

42

OP22 G. Divitini

Electron Microscopy and Multivariate Analysis for dynamical characterisation

of perovskite solar cells

43

OP23 M. Tsvetkov, Ya.-K. Petrova, M. Milanova

Luminescence properties of Gd1.97-xSmxTb0.03Mo3O12 for potential LED

applications

44

OP24 Galina Yotova, Veronika Mihaylova, Boika Zlateva, Stefan Tsakovski

Assessment of the Bulgarian wastewater treatment plants impact on the receiving

water bodies

45

OP25 T. D. Gurkov, R. D. Stanimirova, R. I. Uzunova, K. D. Danov, P. A. Kralchevsky

Interfacial layers of volatile surfactants: adsorption and kinetics of evaporation

46

OP26 Yanlin Zhang, Robert W. Cattrall, Spas D. Kolev

Microfluidic fabrication of micro polymer inclusion beads (µPIBs). Application

to the recovery of gold from electronic scrap

47

OP27 R. I. Tomov, M. Dudek, R.V. Kumar

Inkjet printing of direct carbon solid oxide fuel cell

48


11

OP28

Mihail Georgiev, Lyuba Aleksova, Krassimir Danov, Peter Kralchevsky

Bicontinuous phases from mixed surfactant solutions with enhanced

solubilization capacity and their potential applications

49

OP29 Rumen Lyapchev, Rositsa Kostandieva, Luben Borislavov, Petar Petrov,

Miroslav Dangalov, Nikolay G. Vassilev

NHC-ligands: Imidazopyridine-3-ylidenes versus Imidazoquinoline-1-ylidenes

50

OP30 Ivan Svinyarov, Milen G. Bogdanov

Ionic liquids as alternative solvents in the sample treatment for determination of

biologically active compounds in plants

51

OP31 Ángel Morales-García, Antoni Macià, Stefan T. Bromley, Francesc Illas

Stability or photoactivity? Properties of realistic TiO2 nanoparticles

52

OP32 Hristo Veselinski, Tsveta Sarafska, Stiliyana Pereva, Veselin Petrov,

Tony Spassov

Inclusion complexes of naproxen in amorphous gamma cyclodextrin

53

SHORT ORAL PRESENTATIONS

SO 1 Chaojian Chen, David Yuen Wah Ng, Tanja Weil

Polymer-grafted gold nanoflowers with temperature-controlled catalytic features

by combining ARGET ATRP and metal reduction in one pot

55

SO 2 Hristo Rasheev, R. Stoyanova, Alia Tadjer

Solvation-desolvation thermodynamics in mixed alkaline-ion batteries

56

SO 3 Roger Bujaldón, Dolores Velasco

Extending the carbazole core towards enhanced organic semiconductors

57

SO 4 Fatmegyul Mustan, Nadya Politova, Zahari Vinarov, Slavka Tcholakova,

Damiano Rossetti, Pip Rayment

Surface and foam properties of nonionic surfactant solutions

at high sugar concentration

58

SO 5 Kristina M. Mircheva, Nikolay A. Grozev, Borislav A. Anchev, Daniela S. Tsekova

Physico-chemical properties of L-Asp based Gemini surfactants

59


12

SO 6 Nikoleta Kircheva, Todor Dudev

A DFT/PCM study of the complexation between Ga3+ and ribonucleotide

reductase substrates

60

SO7 Zhihong Ye, Enric Brillas, Francesc Centellas, Pere L. Cabot, Ignasi Sirés

Fe-based MOFs as efficient catalysts for the degradation of emerging

contaminants in urban wastewater

61

SO8 Marc Figueras, Ignacio J. Villar-Garcia, Francesc Viñes, Carmen Sousa, Vcitor

A. de la Peña O’Shea, and Francesc Illas

Correcting flaws in the assignment of nitrogen chemical environments in N-

doped graphene

62

SO9 Anabel Jurado-Mañas, Francesc Viñes

First principles evaluation of the initial oxidation of transition metal surfaces

63

SO10 Konstans Ruseva, Radostina Alexandrova, Maya Argirova, ElenaVassileva

Triple stimuli-responsive interpenetrating polymer network of

poly(carboxybetaine methacrylate)/poly(sulfobetaine methacrylate)

64

SO11

SO12

Mengxi Lin, Albert Figuerola

Synthesis and characterization of nanostructured Pt-Ag-based

chalcogenidesemiconductors

Raul Morales-Salvador, Daniel Gouveia, Ángel Morales-García, Francesc Viñes,

José R.B Gomes, Francesc Illas

Two dimensional Transition Metal Carbides/nitrides (MXenes) as potential

catalysts for CO2 conversion to CO

65

66

SO13 Joan Mariñoso Guiu, Antoni Macià, Stefan. T. Bromley

How to accurately model IR spectra of silicate grains

67


13



PLENARY LECTURES


14

Horizon 2020 Project “Materials Networking” PL1 “Advanced Materials” Workshop


Metallic Glasses: a range of states offering exceptional mechanical properties

A. L. Greer

University of Cambridge, Department of Materials Science & Metallurgy, 27 Charles Babbage Road,

Cambridge CB3 0FS, UK

[email protected]

Focusing on metallic systems, we consider developments in understanding and exploiting the glassy state that is formed when a liquid is cooled into a solid state without crystallizing, having in mind that: "The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of glass and the glass transition" [1]. The metallic glasses are of particular interest for several reasons, not least their excellent mechanical properties. These lead to possible applications, but also open up the possibility of using mechanical working to change the structure and properties of glass [2], something hardly explored for conventional oxide glasses. While plastic deformation can be expected to have structural effects, it is more surprising that there can be significant effects even well within the (nominally) elastic regime [3,4]. In this talk we explore the diversity that can be achieved in the metallic glassy state, from very high energy (‘rejuvenated’) to very low energy (‘relaxed’ and even ‘ultrastable’) states [5]. We also explore the extent to which directionality (anisotropy) can be induced in metallic glasses [6]. In each case, we examine the potential applications of the properties (structural and functional) that can be induced. [1] P.W. Anderson, Science 267, (1995) 1615. [2] Y.H. Sun, A. Concustell, A.L. Greer, Nature Rev. Mater. 1, (2016) 16039. [3] S.V. Ketov, Y.H. Sun, S. Nachum, Z. Lu, A. Checchi, A.R. Beraldin, H.Y. Bai, W.H. Wang, D.V. Louzguine-

Luzgin, M.A. Carpenter, A.L. Greer, Nature, 524, (2015) 200. [4] A.L. Greer, Y.H. Sun, Philos. Mag. 96, (2016) 1643. [5] A.L. Greer, Nature Mater. 14, (2015) 542. [6] Y.H. Sun, A. Concustell, M.A. Carpenter, J.C. Qiao, A.W. Rayment, A.L. Greer, Acta Mater. 112, (2016) 132.


15

Horizon 2020 Project “Materials Networking” PL2 “Advanced Materials” Workshop


First principles modeling of radiation damage:

calculation of the electronic stopping power for polymers

throughnon-adiabatic molecular dynamics simulations

Pere Alemany

Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional

(IQTCUB), Universitat de Barcelona, Barcelona, Spain

[email protected]

Ions shooting through condensed matter dissipate their kinetic energy by transferring it to the target's

electrons and nuclei. At high velocities (above 1% of the speed of light) the stopping is mostly electronic, in

a highly non-equilibrium, non-adiabatic process. First-principles simulations [1,2] of such processes have

been quite successfully performed in the last decade for varied systems. Here we present results for the

electronic stopping power for protons in ideal crystalline organic polymers (polyethylene, polyacetylene,

and isotactic polypropylene), used as simple models for highly anisotropic systems with strong chemical

bonding in one dimension and weakly bound in the other two dimensions. The reported simulations are

based on time-dependent density-functional theory in real time (RT-TDDFT), and using a basis of atomic

orbitals (LCAO) within the SIESTA program. Results of the effect of trajectory orientation and impact

parameter will be presented, displaying a transition from electronic-structure dependence at low velocity, to

a regime at higher velocities in which the particle density along the projectile's path dominates.

References:

1. A. Correa, J. Kohanoff, E. Artacho, D. Sánchez-Portal, A. Caro "Nonadiabatic Forces in Ion-Solid Interactions: The Initial Stages of Radiation Damage", Phys. Rev. Lett 108, 213201 (2012). 2. M. Ashan Zeb, J. Kohanoff, D. Sánchez-Portal, A. Arnau, J.I. Juaristi, E. Artacho, " Electronic Stopping Power in Gold: The Role of d Electrons and the H=He Anomaly", Phys. Rev. Lett. 108, 225504 (2012). Acknowledgments:This work was financially supported by Ministerio de Ciencia, Innovación y Universidades (project

PGC2018-093863-B-C22 ), Ministerio de Educación Cultura y Deportes (Salvador de Madariaga project

PRX17/00269), and Generalitat de Catalunya (project 2017 SGR 1289).


16



KEYNOTE LECTURES

Horizon 2020 Project “Materials Networking”


17

KN1 “Advanced Materials” Workshop 21 – 25 July 2019, St. St. Constantine and Helena, Varna, Bulgaria

Ice-templated and charge-deposited structures for regenerative medicine

Ruth E. Cameron

University of Cambridge, Department of Materials Science and Metallurgy,

27, Charles Baggage Road, Cambridge, CB3 0FS

[email protected]

There is huge interest in the development of biomaterial scaffolds for regenerative medicine, aimed at creating structures to mimic the composition of natural tissue, with space for cell colonisation and for nutrient and oxygen transport. However, despite the diversity of targeted applications, in-service success can be limited. There are a number of contributing factors, but three key common barriers are (a) the need to control cell penetration throughout the structure, (b) the need for selective cell growth and migration, and (c) the need for heterogeneous tissue environments. The answers to these problems lie in the conscious control of the architecture, the physical responses and the biochemical cues within the scaffold, which, in turn, lead to the ability to direct biological response. The talk will describe how ice-templating and electrophoretic deposition technologies can be exploited to create novel, complex and biomimetic 3D environments for the control of tissue growth. The approach is adaptable to a wide range of medical applications, and examples will be highlighted, including those of osteochondral repair, cardiac patches, dermal grafts, breast cancer diagnostics and bioreactors for platelet generation.

Micro computed tomography image of a graded pore architecture in an ice-templated scaffold, colour coded

for pore size (Image: J.H Shepherd)

mailto:[email protected]


18

Horizon 2020 Project “Materials Networking” KN2 “Advanced Materials” Workshop


The role of 2D-like materials in batteries

R Vasant Kumar


[email protected]

In the search for sustainable energy batteries will play a major part. Batteries have been “silent partners” in past technologies that have made major impact. We are in the midst of another major change in electric mobility and stationary storage, where demand for batteries is projected to experience an unprecedented growth [1, 2]. The questions relating to making batteries larger, better, safer, lighter, cheaper and sustainable will loom large in both research and development activities. It is generally agreed that 2D-based materials can offer innovation opportunities in electrochemical energy devices as they can combine good electrical conductivity & connectivity within a suitable porous structure that is able to facilitate rapid redox reactions [3-7]. 2D-like materials are hybridized with other electroactive components for optimal synergy in electrocatalysis and a number of approaches for making the electrode structure in batteries will be presented.

References:

1. Leapfrogging to sustainable power, R.V. Kumar, Chapter in “Smart Villages: New Thinking for Off-Grid Communities Worldwide; Published by Banson (Lavenham Press, UK), 2015, pp. 35-41; ISBN 978-0-9932932-0-7(paperback); 978-0-9932932-1-4 (hardback).

2. P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J. M. Tarascon, Nat. Mater. 2011, 11, 19. 3. Graphene-wrapped Sulfur/Metal Organic Framework (MOF)-Derived Microporous Carbon Composite for

Lithium Sulfur Batteries, R. Chen, T. Zhao, T. Tian, S. Cao, P. Coxon, K. Xi, D.Fairen-Jimenez, R. V. Kumar and A. K. Cheetham, APL Materials, 2(12), 124109, 2014 (Selected as a ‘top’ paper by the Editor, Highlighted in American Institute of Physics (AIP).

4. T. A. Shifa, F. Wang, Y. Liu, J. He, Adv. Mater. 2018, DOI: 10.1002/adma.201804828e1804828 5. Rational approach to guest confinement inside MO cavities for low-temperature catalysis, I Wang, L Gao, J

Hu, S Herau, J Griffiths, W Li, J Dong, S Gao, MM Titrici, RV Kumar, S Smoukov, Nature Communications, volume 10, Article number: 1340 DOI: 10.1038/s41467-019-08972-x, 2019

6. Nitrogen, sulfur co-doped graphene sponge as electroactive carbon interlayer for high energy and power Li-ion batteries, Xing LB, Xi K, Li Q, Su Z, Lai C, Zhao X, Kumar RV; Journal of Power Sources 303:22-28 30 Jan 2016.

7. Y. Wang, J. C. Kim, R. J. Wu, J. Martinez, X. Song, Ji. Yang, F. Zhao, A. Mkhoyan, H. Y. Jeong and M. Chhowalla, “Van der Waals contacts between three-dimensional metals and two-dimensional semiconductors”, Nature 568 (2019) 70-74


19



The control of thin film structures, and applications in materials science

Zoe Barber

Department of Materials Science & Metallurgy, University of Cambridge

27 Charles Babbage Road,

Cambridge, CB3 0FS

[email protected]

We have many years of experience in the application of small-scale, versatile magnetron sputter deposition

systems which allow for great flexibility in the film materials fabricated, their structure and properties. Here

I will describe a variety of projects to illustrate just some of the options available, and the huge range of film

types which we can produce. These examples include dopant additions to hydroxyapatite coatings for

bioactivity; the optimization of three-component shape memory metals and Heusler alloys for device

applications; porous nanostructures for catalysis; multilayers for the study of mechanical defects; and novel,

stable nano-composites. I will also briefly illustrate future directions, with the potential for overcoming

issues of cost and scale-up by use of controlled chemical deposition.


20



Random explorations of material structure space

Chris J Pickard

University of Cambridge, Cambridge, United Kingdom

[email protected]

Over the last decade, high pressure and materials research has been transformed by the ability to predict both

the structures and properties of materials from first principles. In many cases these predictions have been

later confirmed by experiment. In others they have provided fruitful new directions to explore.

This progress has been achieved through the combination of stochastic approaches with reliable and

efficient first principles methods. Diverse ensembles of initial structures can be generated, and structurally

optimized. The resulting low energy structures are candidates for stable, and metastable, phases and/or

defects and interfaces that might be experimentally realized. Success, of course, depends on a sufficiently

broad and thorough sampling of configuration space.

A purely random strategy, as employed by Ab Initio Random Structure Searching (AIRSS), [1,2] is entirely

parallel, and a natural fit to the high throughput computation (HTC) paradigm. Challenging cases can be

tackled by designing the initial random structures so that they focus the search in regions of configuration

space that are anticipated to yield success.

The design of these random “sensible” structures will be explored, along with some new directions [3]

which promise to accelerate random search, and applications to high pressure and materials research – from

dense hydrides approaching room temperature superconductivity, to surprising astrophysical reactions and

complex interfacial materials.

References:

[1] C. J. Pickard, and R. J. Needs, Phys. Rev. Lett., 97 (4), 045504 (2006) & JPCM, 23(5), 053201 (2011) [2] Released under the GPL2 license: http://www.mtg.msm.cam.ac.uk/Codes/AIRSS [3] C. J. Pickard, “Hyperspatial optimization of structures”, Phys. Rev. B, 99, 054102 (2019)

Acknowledgments:

This work was supported by the Royal Society through a Wolfson Research Merit Award, and the EPSRC.


21



ORAL PRESENTATIONS


22

Horizon 2020 Project “Materials Networking” OP1 “Advanced Materials” Workshop


Mechanofluorescent liquid-crystalline elastomers

Jaume Garcia-Amorós and Dolores Velasco

Grup de Materials Orgànics, Institut de Nanociència i Nanotecnologia (IN2UB), Departament de Química

Inorgànica i Orgànica (Secció de Química Orgànica), Universitat de Barcelona, Martí i Franquès 1, E-

08028, Barcelona, Spain

[email protected]

Carbazole-containing nematic liquid single crystal elastomers (LSCEs) alter their luminescence upon the

application of an external mechanical force. Therefore, they are valuable flexible materials to detect

mechanical events with simple fluorescent measurements. In this work, we have focused our attention on the

main principles underlying the operation of these materials and the development of novel design schemes to

produce efficient elastomeric fluorescence sensors for force detection. In this context, comprehending and

controlling the interactions established between the distinct components of the active material, i.e. mesogens

and fluorophores, is essential to achieve force-sensitive materials with improved performances. With this

purpose in mind, we have explored the role of several structural features on such phenomenon, for instance,

the type of connection (end-on or side-on) of the carbazole fluorophores to the elastomeric network, the

length of the alkyl chain that binds them to the main polysiloxane backbone and the nature and organization

of the host liquid-crystalline phase.[1–4] In summary, throughout our research we have elucidated not only the

driving force but also the role of those structural features controlling the mechanoluminescent behavior of

these functional materials, which is essential to rationalize this effect and possibly guide the future design of

LSCE-based force sensors with improved performances.

References:

1. J. Garcia-Amorós, D. Velasco, Macromol. Rapid Commun. 2015, 36, 755−761.

2. J. Garcia-Amorós, S. Bassaganyas, D. Velasco, Phys. Chem. Chem. Phys. 2016, 18, 5108–5111.

3. D. Escalera-López, J. Garcia-Amorós, D. Velasco, Macromol. Chem. Phys. 2018, 218, 1700550.

4. D. Heras, M. Reig, N- Llorca-Isern, J. Garcia-Amorós, D. Velasco, ACS Appl. Polym. Mater. 2019, 1, 535–541.

Acknowledgments: Financial support from the Ministerio de Economía y Competitividad (Spain, grant CTQ2015-

65770-P MINECO/FEDER) is gratefully acknowledged.


23



Computational modeling of H/H+ migration in porous layered materials

Petko Petkov,1 Yun An,3 Agnieszka Kuc,2,3 Thomas Heine,2,3,4 1Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria, e-

[email protected]

2Helmholtz-Zentrum Dresden-Rossendorf, Abteilung Ressourcenökologie, Forschungsstelle Leipzig,

Permoserstr. 15, 04318, Leipzig, Germany

3Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2,

04103 Leipzig, Germany

4Theoretical Chemistry, TU Dresden, Mommsenstr. 13, 01062 Dresden

Spatial confinement has strong impact on the chemical properties of molecules. The layers of h-BN, MoS2,

and graphene are chemically very stable, if not inert, and the interlayer interactions impose pressure on the

intercalated species. So, the chemistry in the interstitial space of a layered material is expected to be

significantly different from the surface-adsorbed counterpart. Based on first-principles calculations

combined with well-tempered metadynamics simulations, we report the chemical interactions and mobility

of protons (H+) and protium (H) in the interstitial space of these layered materials. We show that both H+ as

well as H can be transported between the layers of h-BN and MoS2 with low free energy barriers, while they

are immobilized in graphite, in accordance with experimental observations.

Figure 4. Schematic representation of the proton hopping process in hBN, going via four nitrogen atoms N1 N2 N3 N4. These hopping events are observed in a Born-Oppenheimer metadynamics simulation (right), where the N-H distance is plotted with respect to the closest N atom.

Acknowledgments: PPetkov is thankful to the “Materials Networking” project funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 692146, and to NSF – Bulgaria project No: KП-06-ДО02/2


24



Computational assessment of the performance

of a drug-delivery system component

Kai S. Exner,1 Anela Ivanova1 1University of Sofia, Faculty of Chemistry and Pharmacy, Department of Physical Chemistry, 1 James

Bourchier Avenue, 1164 Sofia, Bulgaria

[email protected], [email protected]

Efficient drug delivery in the human organism requires the application of drug-delivery systems (DDS) that

consist of several building blocks. Herein, we present a combination of molecular dynamics (MD)

simulations and density functional theory (DFT) calculations for a potential DDS component for transport of

the cytostatic doxorubicin (DOX), one of the widely used anthracycline chemotherapeutic agents due to its

diverse activity against a wide range of tumors.1 The DDS model consists, besides one drug molecule, of a

thiolate-protected gold nanoparticle (Au-NP)2 as carrier material and a specific drug-binding peptide

(DBP).3 The Au-NP and the DBP are covalently linked by a Au–S bond and DOX is pre-adsorbed on a

tryptophan residue (W5) of the DBP, as obtained in a recent MD study of Gocheva et al.4

MD simulations are conducted in a NPT ensemble at physiological conditions (T = 310 K, p = 1 bar, cNaCl =

154 mmol/L), mimicking those of the human body. Interestingly, it turns out that the task of the Au-NP is

not limited to being a carrier only: instead, the Au-NP is directly involved in the interaction with the drug,

since within the preferred adsorption state DOX is intercalated between the Au-NP and the tryptophan

residue W5 of the peptide in a sandwich-like arrangement: NP–DOX–W5. This configuration is in dynamic

equilibrium with a second adsorption state, in which solely the tryptophan residue of the peptide stacks the

drug: DOX–W5. DFT calculations are applied to quantify the energetic stabilization of the drug in both

adsorption configurations. The entropy change is accounted for in addition to the DFT binding energies. The

construction of a Volcano plot, a well-established tool in the field of catalysis and battery research,5 provides

an explanation for the preference of the NP–DOX–W5 intercalation structure: the main reason for the

proximity of DOX to the Au-NP can be traced back to an entropic stabilization of both the drug and the NP.

References:

1. Nadas, J.; Sun, D. Expert Opin. Drug Discovery 2006, 1, 549. 2. Lopez-A., O.; Akola, J.; Whetten, R.L.; Grönbeck, H.; Häkkinen, H. J. Phys. Chem. Lett. 2009, 113, 5035. 3. Zheng, Z.; Aojula, H.; Clarke, D. J. Drug Target. 2010, 18, 477. 4. Gocheva, G.; Ilieva, N.; Peneva, K.; Ivanova, A. Chem. Biol. Drug Des. 2018, 91, 874. 5. Exner, K.S. ChemSusChem 2019, 12, 2330.




25



Colloidal noble metal-based ternary chalcogenide nanocrystals

with tunable composition

Albert Figuerola,1,2* Mariona Dalmases,1,2 Pau Torruella,2,3 Javier Blanco-Portals,2,3

Sònia Estradé, 2,3 Francesca Peiró, 2,3 1 Departament de Química Inorganica i Organica, Seccio de Química Inorganica,

2 Institut de Nanociencia i Nanotecnologia (IN2UB) and

3 Laboratory of Electron Nanoscopies (LENS)-MIND/IN2UB, Departament d’Electronica

all Universitat de Barcelona, Martí i Franques 1-11, 08028 Barcelona, Spain

[email protected]

The optimization of a material functionality requires both the rational design and precise engineering of its

structural and chemical parameters. [1] Colloidal chemistry is an excellent synthetic choice for the synthesis of

homogeneous and compositionally complex novel nanostructured systems with potential application in several

fields. [2] We have exploited here several surfactant-assisted synthetic strategies in order to chemically transform

our starting silver or copper chalcogenide nanocrystals into compositionally more complex nanostructured

systems, such as hybrid and ternary I-I-VI semiconductor nanocrystals with different stoichiometries. Our results

indicate the formation of new ternary materials, both with stoichiometric and non-stoichiometric compositions.

Considering the complex chemical distribution of the species in the materials, the use of advanced atomic-

resolution electron microscopy techniques was key for their appropriate characterization and elucidation of

formation mechanisms. The work is complemented with the assessment of their potential as active materials for

energy conversion devices and as contrast agents in clinical diagnosis.

Figure. Chemical transformation of binary chalcogenide nanostructured materials into more complex noble

metal-based chalcogenide systems with a ternary or hybrid composition. (M stands from Ag or Cu while X

represents S, Se or Te)

References:

1. M. V. Kovalenko, L. Manna, A. Cabot, Z. Hens, D. V. Talapin, C. R. Kagan, V. I. Klimov, A. L. Rogach, P. Reiss, D. J. Milliron, P. Guyot-Sionnnest, G. Konstantatos, W. J. Parak, T. Hyeon, B. A. Korgel, C. B. Murray, W. Heiss, ACS Nano 2015, 9, 1012-1057. 2. U. Banin, Y. Ben-Shahar, K. Vinokurov, Chem. Mater. 2014, 26, 97−110. Acknowledgments: The authors acknowledge financial support from the Spanish Ministerio de Economia y Competitividad (MINECO) through CTQ2015-68370-P and MAT2016-79455-P. A.F. is a Serra Hunter fellow.


26



Synthesis and chemical properties of 3-phosphonocoumarins as precursors for

bioactive compounds

Ana I. Koleva, Nevena I. Petkova-Yankova, Rositca D. Nikolova

Department of Organic Chemistry and Pharmacognosy, Faculty of Chemistry and Pharmacy, Sofia

University “St. Kliment Ohridski”, 1 J. Bouchier buld., 1164 Sofia, Bulgaria

[email protected]

Phosphoruscontaining structures such as compound 1, presented in the Scheme, are of a great importance in

the areas of pharmacology, chemistry and agriculture due to the similarity of phosphorus compounds to the

naturally occurring carboxylic acid derivatives and their possible application in diverse biological systems.

The combination of the two fragments - a coumarin system containing a phosphoryl group - could open a

route to a new class of compounds, which structures might possess wide spectrum of biological activities

due to the presence of the different functional groups.

Scheme: Phosphoruscontaining structures 1 and their chemical properties.

The particular interest towards this class of organic compounds is due to their potential application as

acceptors in different organic reactions with nucleophillic reagents and 1,3-dipolar cycloaddition reactions

as well as to their application as intermediates in the synthesis of products of practical interest proving their

biological activity as new therapeutics.

References:

1. Ana I. Koleva, Nevena I. Petkova-Yankova, Rositca D. Nikolova Molecules 2019, 24 (11), 2030-2068. Acknowledgments: The authors are grateful to the Materials Networking—Spreading Excellence and Widening Participation H2020-TWINN-2015 for the funding. A.I.K. acknowledges the financial support received from the program “Young scientists and Postdoctoral candidates” of the Bulgarian Ministry of Education and Science, MCD No. 577/17.08.2018The work was assisted by University Scientific Fund (Grant No. 80-10-154/2019).


27



Fluorescence correlation spectroscopy studies of drug nanocarriers in flowing blood

Kaloian Koynov, Jennifer Schultze, Inka Negwer, Stoyan Yordanov, Hans-Jürgen Butt

Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany

[email protected]

Using nanoparticle-based carriers is an extremely promising way for the administration of therapeutic

agents, such as drug molecules, proteins and polynucleotides. However, in order to get full advantage of this

approach and develop efficient nanocarrier systems, a careful characterization at all stages of the drug

delivery process is needed. In particular, one needs to monitor and quantify: the encapsulation of the

therapeutic agents during preparation; the possible interactions of the nanocarriers with e.g. plasma proteins

and their stability in the blood stream; the kinetic of drug release in the cytoplasm of the target cells.

In this presentation I will show that due to its very high sensitivity, selectivity and sub-femtoliter probing

volume the fluorescence correlation spectroscopy (FCS) technique[1] is a very powerful and versatile tool for

such studies. FCS measures the diffusion coefficient, hydrodynamic radius, local concentration and

fluorescence brightness of fluorescent molecules and nanoparticles, thus allowing monitoring of the

formation of nanocarriers, drug loading efficiency, stability or kinetics of drug release. First, I will discuss

examples of such FCS studies performed in aqueous environments. Next, I will present very recent results

on FCS characterization of nanocarriers in human serum and flowing blood.[2]

References:

1. Koynov K and Butt H-J: “Fluorescence correlation spectroscopy in colloid and interface science“ Current Opinion

in Colloid & Interface Science 17, 377 (2012). 2. Negwer I, Best A, Schinnerer M, Schafer O, Capeloa L, Wagner M, Schmidt M, Mailander V, Helm M, Barz M,

Butt HJ, Koynov K: “Monitoring drug nanocarriers in human blood by near-infrared fluorescence correlation spectroscopy” Nature Communications 9, 5306 (2018).

Acknowledgments: The authors gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft

(SFB 1066, Q2) and the European Union’s Horizon 2020 programme (grant agreement No 692146).


28



Super-macroporous polysaccharide cryogels: Synthesis and application as drug

carriers and cell scaffolds

Petar D. Petrov,1 Yavor Danov,1 Denitsa Momekova2

1Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. Bonchev St. 103A, 1113 Sofia,

Bulgaria, e-mail: [email protected]

2Faculty of Pharmacy, Medical University-Sofia; 2 Dunav St., 1000 Sofia, Bulgaria

Research and development of biodegradable polymeric materials have significantly contributed to

various advancements in drug delivery, tissue engineering, and medical device improvement. In the last two

decades, there is a particular interest in the so-called cryogels, which are super-macroporous hydrogels

formed via cryogenic processing. Cryogels are sponge-like materials possessing very quick mass transport

and heat exchange properties.

The present talk focuses on the synthesis of i) pH-sensitive cryogels, based on two biodegradable

natural polymers chitosan (CS) and 2-hydroxyethylcellulose [1]; ii) electrically conducting 2-

hydroxyethylcellulose/polyaniline nanocomposite cryogel carriers of cells [2]; and iii) nanocomposite

hydroxypropyl cellulose cryogels containing core-shell micelles[3] by cryogenic treatment and photo-

chemical crosslinking. The effect of experimental conditions and polymer nature on the gel fraction yield,

swelling degree, cryogel morphology and mechanical properties is studied. Finally, the potential application

of different cryogel carriers for sustained delivery of hydrophilic and hydrophobic drugs as well as cell

scaffolds is discussed.

References:

1. V. Stoyneva, D. Momekova, B. Kostova, P. Petrov, Carbohydrate Polymers, 2014, 99, 825-830. 2. P. Petrov, P. Mokreva, I. Kostov, V. Uzunova, R. Tzoneva, Carbohydrate Polymers, 2016, 140, 349-355. 3. V. Pencheva, E. Margaritova, M. Borinarova, M. Slavkova, D. Momekova, P. D. Petrov, Carbohydrate Polymers 2018, 183, 165-172. Acknowledgments: This work was partially supported by the Bulgarian Ministry of Education and Science (Grant

D01-217/30.11.2018) under the National Research Programme “Innovative Low-Toxic Bioactive Systems for

Precision Medicine (BioActiveMed)” approved by DCM # 658 / 14.09.2018


29



Neural cell scaffolds and biohybrid hydrogels from peptide nanofibers

Christopher V. Synatschke, Thomas Mack, Jasmina Gacanin, Adriana Sobota, Tanja Weil

Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany

[email protected]

Short peptides that assemble into hierarchically ordered supramolecular nanostructures have recently gained

attention as functional biomaterials. 1D assemblies of such peptides are of particular interest as these

structures are typically difficult to obtain from conventional synthetic polymers. Here, we present nanofiber-

forming peptides that have shown great promise in a number of biomedical applications, including their use

as bioactive coatings and 3D cell scaffolds. When applied as coatings, several nanofiber forming peptide

sequences were identified that supported the growth of primary neurons, and promoted cellular adhesion,

survival, and neurite outgrowth. In an injury model of the facial nerve responsible for controlling whisker

movement, the mice injected with the most potent peptides from the in vitro screening showed an enhanced

functional recovery of the whisker movement (Figure 1a), compared to controls.

Additionally, nanofiber-forming peptides were employed as supramolecular crosslinkers in biocompatible

bulk hydrogels. Due to the non-covalent nature of the crosslinkers, the gels show remarkable rheological

properties, allowing the material to flow under shear, reforming instantly after removing the shear stress,

rendering the gels injectable (Figure 1b). Furthermore, the hydrogels can support different types of cells,

such as endothelial cells and neurons, which actively migrate into the material over the course of several

days. The presented examples highlight the great potential for various biomedical applications of peptide-

based nanomaterials.

Figure 1. a) Functional recovery of whisker

movement in facial nerve injury model 18 days

post injury, after injection of nanofiber-forming

peptide. b) Thixotropic behavior of non-

covalently crosslinked hydrogel allowing for

injection through a needle.


30



The neurotoxin VIPOXIN and its action on model membrane systems and living cells

Kristina Mircheva1, Svetla Petrova2, Nikolai Grozev1, Tzvetanka Ivanova1, Ivan Panaiotov1, Konstantin

Balashev1 1Dept. of Physical Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia, 1, James Bouchier

Blvd., Sofia 1164, Bulgaria,

2Dept. of Biochemistry, Faculty of Biology, University of Sofia, 8, Dragan Tsankov Blvd., Sofia 1164,

Bulgaria,

[email protected]

Snake venoms are complex mixtures of pharmacologically active proteins and polypeptides interfering

in various physiological systems. They have been studied in search of the molecular basis of toxicity, have

provided important biological tools to investigate vital physiological processes, and even have been used as

therapeutic agents.

The neurotoxin Vipoxin is isolated from the venom of the Bulgarian viper Vipera ammodytes

meridionalis. Structurally Vipoxin represents a heterodimeric postsynaptic ionic complex composed of two

protein subunits— a basic and strongly toxic secretory phospholipase A2 (sPLA2) enzyme and an acidic,

enzymatically inactive and nontoxic component, originally named Inhibitor.

We’ll demonstrate how as a model system the classical Langmuir monolayer could be used for

studying the enzyme hydrolysis and how the Michaelis-Menten kinetic model is modified in order to be

obtained important kinetic constants of the enzyme reaction.

Some recent results which show how Atomic Force Microscopy (AFM) could be applied for studying

the mechanical response of living cells exposed to the action of the Vipoxin, will also be reported.

References:

1. K. Mircheva, S.D. Petrova, Tz. Ivanova, I. Panaiotov, K.T. Balashev, Action of Vipoxin and its separated components on monomolecular film of Dilauroylphosphatidylcholine at the air/water interface, Colloids and

Surfaces A: Physicochemical and Engineering Aspects, 562, (2019), 196-202

Acknowledgments: The authors are grateful to grant Horizon 2020 project ID: 692146-H2020-eu.4.b “Materials Networking”. K.Balashev also acknowledges Fulbright grant 18-21-05



31



How Pb2+ binds and modulates properties of Ca2+ - signaling proteins

Todor Dudev1, Cedric Grauffel2 and Carmay Lim2

1Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria 2Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan

[email protected]

Abiogenic lead (Pb2+), present in the environment in elevated levels due to human activities, has detrimental

effects on human health. Metal-binding sites in proteins have been identified as primary targets for lead

substitution resulting in malfunction of the host protein. Although Pb2+ is known to be a potent competitor of

Ca2+ in protein binding sites, why/how Pb2+ can compete with Ca2+ in proteins remains unclear, raising

multiple outstanding questions, including the following: (1) What are the physicochemical factors governing

the competition between Pb2+ and Ca2+? (2) Which Ca2+-binding sites in terms of the structure, composition,

overall charge, flexibility, and solvent exposure are the most likely targets for Pb2+ attack? Using density

functional theory combined with polarizable continuum model calculations, we address these questions by

studying the thermodynamic outcome of the competition between Pb2+ and Ca2+ in various model Ca2+-

binding sites, including those modeling voltage-gated calcium channel selectivity filters and EF-hand and

non-EF-hand Ca2+-binding sites. The results, which are in good agreement with experiment, reveal that the

metal site’s flexibility and number of amino acid ligands dictate the outcome of the competition between

Pb2+ and Ca2+: If the Ca2+-binding site is relatively rigid and crowded with protein ligands, then Pb2+, upon

binding, preserves the native metal-binding site geometry and at low concentrations, can act as an activator

of the host protein. If the Ca2+-binding site is flexible and consists of only a few protein ligands, then Pb2+

can displace Ca2+ and deform the native metal metal binding site geometry, resulting in protein malfunction

Acknowledgments: T.D. was supported by the project Materials Networking H2020-TWINN-2015


32



Spectral characterization of poly(propylene imine) metallodendrimers in solution and

onto cotton fabrics and their antimicrobial and antibiofilm activity

Stanislava Yordanovaa, Stanimir Stoyanova, Desislava Stanevab, Ivo Grabchevc aSofia University “St. Kliment Ohridski”, Faculty of Chemistry and Pharmacy, 1164 Sofia, Bulgaria

bUniversity of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria

cSofia University “St. Kliment Ohridski”, Faculty of Medicine, 1407 Sofia, Bulgaria

[email protected]

Poly(propylene imine) dendrimers from first and third generation modified with 1,8-naphthalimide units and

their Cu(II) complexes have been characterized by fluorescence and EPR spectroscopy. Cotton fabric has

been modified with these dendrimers and their color characteristics were determinated. The antimicrobial

activity of dendrimer ligands and their Cu(II) complexes in solution and after their deposition on a cotton

fabric was investigated. Good antibacterial effect of dendrimer ligands has been obtained, which is enhanced

at their Cu(II) complexes. After their deposition on cotton fabric metallodendrimers exhibit good antibiofilm

activity.

Scheme 1. Chemical structure of poly(propylene imine) metallodendrimer

Acknowledgments: The authors acknowledge Grant № КОСТ, 01/3-2017, Fund “Scientific Research”, Ministry of Education and Science of Bulgaria


33



LiMnPO4-olivine deposited on microporous alloy as additive-free electrodes for

lithium ion batteries

L. Mihaylov1, T. Boyadzhieva2, V. Kumar3, R. Tomov3, V. Koleva2, R. Stoyanova2,*, T.Spassov1,*

1Sofia university “St. Kl. Ohridski”, Faculty of chemistry and pharmacy, 1164 Sofia, Bulgaria

2Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

3Department of Materials Science & Metallurgy, University of Cambridge, Cambridge CB3 0FS

[email protected]

A new strategy for fabrication of binder- and carbon-free electrodes for Lithium ion batteries is

demonstrated. The strategy is based on the employment of a nanoporous metallic structure as mechanically

stable and conductive scaffold inside of which an active material is directly grown. The porous metallic

structures with a pore size less than 1 μm were obtained by dealloying microcrystalline Cu60Ag30Al10,

applying the method of selective dissolution of the less noble metals from the alloy. The active material

includes LiMnPO4 olivine, which displays higher power energy in comparison with the well-known

LiFePO4 (701 Wh/kg versus 586 Wh/kg). The improved electrode capacity can be explained by the

enhanced diffusion of Li+ into LiMnPO4, achieved by decreasing the size of the phospho-olivine particle,

incorporated inside the pores of metallic structure. This approach enables to perform precise engineering of

the particle size, which on its turn contributes to improvement of electrochemical properties of phospho-

olivines. As far as we known, this is the first report on the fabrication of LiMnPO4-based electrodes by

avoiding of any electrochemical-inactive additives.

Acknowledgments:

This work has received funding from the National Research Program “Low Carbon Energy for the Transport and Household (E+)” (DO1-214/28.11.2018) granted by the Bulgarian Ministry of Education and Sciencе. The collaboration with Cambridge University, Department of materials science & metallurgy was supported by the project Materials Networking.


34



Singlet fission - a magic bullet for organic photovoltaics

Joanna Stoycheva1,2, Julia Romanova1, Artur Nenov2, Alia Tadjer1

1Faculty of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria

2Dipartimento di Chimica Industriale, Università degli Studi di Bologna, Bologna, Italy

[email protected]

Nowadays, organic alternatives of classical inorganics are sought after in all areas of materials science. Due

to their low cost, light weight and flexibility, organic photovoltaics are also among them, in spite of their

low efficiency. However, the process of singlet fission (SF) some organic molecules can undergo, bears

promise for prominent increase of their efficiency, which will be able to compete with, and even outshine

the classical silicon solar cells.

A recognized class of SF chromophores are the longer polyacenes and their nitrogen-doped analogs [1, 2].

To our knowledge, this is the first report on the employment of boron-doping as a strategy for modelling

new SF materials. It is also the first attempt to include phenanthrenes in the quest for SF candidates. This

study presents a set of symmetrical diboronated anthracenes and phenanthrenes, using multireference ab

initio calculations in order to estimate the SF propensity. The geometry, stability, absorption spectra and

open-shell character of the species are summarized. The results show that the molecular topology is critical

for the optical properties and, respectively, for the SF proclivity. Several di-boron-doped compounds are

outsingled as prospective SF candidates. Structure-properties correlations are established based on molecular

topology. The latter can serve as guidelines in the molecular design of SF photovoltaics.

References:

1. Smith, M. B.; Michl, J. Recent advances in singlet Fission. Annu. Rev. Phys. Chem. 2013, 64, 361–386. 2. Casanova, D. Theoretical modeling of singlet fission. Chem. Rev. 2018, 118, 7164–7207

Acknowledgments: The research was funded by project SURF 80-10-168/2019 and the National Research Program

E+, grant D01-214/28.11.2018.



35



Efficient methods for preparation of emulsions and nanoemulsions

Slavka Tcholakova, Nikolai Denkov

Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia

University, 1 J. Boucher Ave., 1164 Sofia, Bulgaria

[email protected]

This presentation will summarize briefly our current understanding for efficient formation of emulsions

containing micrometer and nanometer sized droplets. The subtle relations between the material

characteristics of the emulsions (oil type, emulsifier, pH, etc.) and the optimal hydrodynamic conditions for

emulsification will be discussed in the context of obtaining emulsions with desired properties. The

differences between oil-in-water and water-in-oil emulsions will be briefly discussed [1-3]. Special focus

will be given on the recent advance in production of nanoemulsions using high pressure homogenizers, high

viscosity of the continuous phase, and/or high oil volume fraction during emulsification [4-5]. Some new

methods for self-emulsification will be briefly reviewed [6-7]. The basic physicochemical and

hydrodynamic concepts will be illustrated by multiple examples with real systems.

References:

1. S. Tcholakova, N. D. Denkov, and A. Phys. Chem. Chem. Phys. 10 (2008) 1608-1627.

2. N. Politova, S. Tcholakova, N. D. Denkov, Colloids Surfaces A 522 (2017) 608–620.

3. N. Politova, S. Tcholakova, S. Tsibranska, N. D. Denkov, K. Muelheims, Colloids Surfaces A 531 (2017) 32–39.

4. S. Tcholakova, I. Lesov, K. Golemanov, N. Denkov, S. Judat, R. Engel, T. Daner, Langmuir 27 (2011) 14783-14796.

5. D. Gazolu-Rusanova, I. Lesov, S. Tcholakova, N. Denkov, B. Ahtchi, Food grade nanoemulsion preparation by rotor-stator homogenization. Food Hydrocolloids (2019) under review.

6. S. Tcholakova, Z. Valkova, D. Cholakova, Z. Vinarov, I. Lesov, N. D. Denkov, K. Smoukov, Efficient Self-Emulsification via Cooling-Heating Cycles. Nature Comm. 8 (2017) 15012.

7. Zh. Valkova, D. Cholakova, S. Tcholakova, N. Denkov, S. K. Smoukov, Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops. Langmuir 33 (2017) 12155−12170.


36



Multilayer formation in Self-Shaping emulsion droplets

Zh. Valkova, 1 D. Cholakova, 1 S. Tcholakova, 1 N. Denkov, 1 S. K. Smoukov2

1 Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia

University, Bulgaria

2 Active and Intelligent Materials Lab, School of Engineering and Materials Science, Queen Mary

University of London, Mile End Road, London E14NS, UK

[email protected]

In several recent studies, it was shown that micrometer-sized drops from alkanes, alkenes, alcohols,

triglycerides, or mixtures of these components can “self-shape” spontaneously into various non-spherical

shapes upon cooling, such as regular polyhedrons, platelets, rods, and fibers.[1÷4] Тhe spontaneous

deformations of the emulsion drops were explained by assuming that intermediate plastic rotator phase,

composed of ordered multilayers of oily molecules, is formed beneath the drop surface around the freezing

temperature of oil.[1÷3] This study presents new results, obtained by differential scanning calorimetry (DSC),

which quantify the enthalpy effects accompanying the drop-shape transformations. By optical microscopy,

we were able to relate the obtained peaks in the DSC thermograms to the specific changes in the drop shape.

From the enthalpies measured by DSC, we determined the fraction of the intermediate phase involved in the

processes of drop deformation. The obtained results support the explanation that the drop-shape

transformations are intimately related to the formation of ordered multilayers of alkane molecules with

thickness varying between several and dozens of layers of alkane molecules, depending on the specific

system.

References:

1. N. Denkov, S. Tcholakova, I. Lesov, D. Cholakova, S. K. Smoukov, Nature 2015, 528, 392-395. 2. D. Cholakova, N. Denkov, S. Tcholakova, I. Lesov, S. K. Smoukov Adv. Colloid Interface Sci. 2016, 235, 90-107. 3. D. Cholakova, N. Denkov. Adv. Colloid Interface Sci. 269 (2019) 7–42. 4. D. Cholakova, Z. Valkova, S. Tcholakova, N. Denkov, S. K. Smoukov, Langmuir 2017, 33, 5696-5706. 5. D. Cholakova, N. Denkov, S. Tcholakova, Z. Valkova, S. K. Smoukov, Langmuir 2019, 35, 5484–5495.

Acknowledgments: This work was funded by the European Research Council (ERC) grant to Stoyan Smoukov, EMATTER (# 280078). The study falls under the umbrella of European network COST MP 1305.



37



Speciation of Cr, Mn and Hg in environmental samples by using composite sorbents based on noble nanoparticles embedded in thin films

Penka Vassileva, Irina Karadjova, Tanya Yordanova, Elisaveta Mladenova

University of Sofia “St. Kliment Ohridski”Faculty of Chemistry and Pharmacy,

Blv. J. Bourchier 1, 1164 Sofía, Bulgaria

[email protected]

Nowadays, due to extended information about the physiological effects of particular chemical species

and their harmful impact on the environment and human health, versatile analytical methods able to

determine hazardous substances at nano‐ and pico‐levels and simultaneously to accomplish reliable

speciation analysis are necessary to meet the requirements of EU legislation. Modern speciation analysis is

currently progressing in two main directions – hyphenated chromatographic approach which ensures

simultaneous determination of as many as possible species of the element (quite expensive and time

consuming) and non‐chromatographic methods for the quantification of one or two most toxic species of the

element (simple and useful for routine application). From the analytical view point, non‐chromatographic

speciation protocols demand excellent separation of chemical species achieved by quantitative adsorption of

the target form(s) followed by quantification with an appropriate instrumental method. Accordingly, sorbent

materials play a crucial role in the accurate and reliable determination of the particular chemical species of

interest because the highest selectivity at the sorption (or elution) stage is a basic requirement for each

extraction based speciation technique. Combined between the well-known beneficial features of SPE

procedures (low solvent consumption, performance simplicity, rapidity, high enrichment factors, flexible

working in batch or column mode), with high selectivity of new functional materials with easily tunable

properties is a reasonable alternative for the purposes of speciation analysis of trace elements. The

successful application of composite materials based on noble nanoparticles embedded in thin films as

efficient sorbents for speciation of Cr, Mn and Hg in environmental samples is summarized in present study.

The developed analytical procedures, achieved detection limits and reproducibility were discussed as well as

their validation and practical application to real samples were demonstrated.

Acknowledgments: The authors gratefully acknowledge the financial support provided by Bulgarian Scientific Fund,

Grant DN19/10 “Smart Speciation”.


38



Common tea for smoking?

Trends and cases in Bulgaria

Ivo D. Ivanov1,2, Silviya Stoykova1,2, Nikola Burdzhiev3, Ivayla Pantcheva1, Vasil N. Atanasov1,2 1 Department of Analytical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment

Ohridski”, 1, J. Bourchier blvd., 1164 Sofia, Bulgaria

2 Department of Toxicology, Military Medical Academy, 3, St. G. Sofiiski str., 1606 Sofia, Bulgaria

3 Department of Organic Chemistry and Pharmacognosy, Faculty of Chemistry and Pharmacy, Sofia

University “St. Kliment Ohridski”, 1, J. Bourchier blvd., 1164 Sofia, Bulgaria

[email protected]; [email protected];

Synthetic cannabinoids (SCs) are novel psychoactive substances, which replicate the effects of natural

Δ9-tetrahydrocannabinol (THC) but they are more potent and have been associated with dangerous adverse

effects as respiratory difficulties, hypertension, tachycardia, chest pain, muscle twitches, acute renal failure,

anxiety, agitation, psychosis, suicidal ideation, and cognitive impairment. Many of them are

pharmacologically uncharacterized and are without any study of their toxicity profile and therefore they pose

a risk to human health.

SCs’ products are primarily sold as “herbal smoking blends” under different brand names. These are

prepared as dried plant material was sprayed with acetonic solution, containing corresponding compound/s.

Over the last few years, an ever increasing number of herbal mixtures, containing SCs of various structure,

have been promoted and now represent a large assortment of new popular recreational drugs, which are

difficult to properly identify. In the present study, a few cases of identification of inflicted SCs on seized

herbal mixture using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance

(NMR) are reported.

The performed experiments determine the presence of the following SCs: 5F-PB-22 (5F-QUPIC),

MDMB-CHMICA (MMB-CHMINACA), 5F-ADB (5F-MDMB-PINACA), FUB-AMB (AMB-

FUBINACA) and 5F-MDMB-PICA (MDMB-2201). Firstly, they have been identified by GC-MS and after

that their structure are confirmed with second technique based on a different analytical principle – NMR.




39



ICP-MS characterization of Bulgarian bottled mineral and spring waters

Valentina Lyubomirova, Veronika Mihaylova and Rumyana Djingova

University of Sofia, Faculty of Chemistry and Pharmacy, 1, Trace Analysis Laboratory,

James Bourchier blvd., BG-1164-Sofia

[email protected]

Bulgaria is the second richest country in Europe after Iceland of mineral and spring water of natural origin,

unique composition and drinking qualities. The story of Bulgarian mineral springs dates back to antiquity.

There are over 800 mineral springs and boreholes, the water of which varies in chemical composition,

temperature and health effects.

There are different categories of bottled waters, different manufacturers and brands. According to the

National Register of the Ministry of Health in 2019 in Bulgaria 69 producers of bottled waters are registered.

Of these around 22 companies bottle natural mineral waters, 12 - spring and 39 - table, some of them bottle

more than one category. Bottled water brands from other countries mainly Italy, France, Macedonia,

Norway, etc. are also available on the Bulgarian market

The major components of bottled Bulgarian drinking waters, such as K, Na, Ca, Mg, and Fe are

monitored in accordance with European legislation. Although the quality of drinking water

depends to a large extent on its microelement composition, only limited data are available about

their trace element content.

In the present study, a representative set of mineral and spring water brands have been studied. Using ICP-

MS spectrometry, a simultaneous determination of matrix and microcomponents in bottled mineral and

spring waters purchased from commercial network of Bulgaria has been performed. The water samples were

analyzed for 70 chemical elements and a correlation between water type, local origin and composition was

estimated.

Acknowledgements: This work is part of project BG05M2OP001-1.002-0019:„Clean technologies for sustainable environment – water, waste, energy for circular economy“ (Clean&Circle) 2018 – 2023, for development of a Centre

of Competence, financed by the Operational programme “Science and Education for Smart Growth” 2014-2020, co-

funded by the European union through the European structural and investment funds.

The authors are grateful to the Horizon 2020 project ID: 692146-H2020-eu.4.b “Materials Networking”



40



Local temperature and oxygen sensing in water environment using annihilation

upconversion materials embedded in wax-matrices

R. Dimitrova2, S. Baluschev1, 2, K. Landfester1 1 Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

2 Sofia University “St. Kliment Ochridski”, 5 James Bourchier Blvd., 1164 Sofia Bulgaria

[email protected]

Decrease of phosphorescence intensity or phosphorescence life time decrease is widely used for T– sensing

or O2– sensing in life-science objects [1, 2]. Local temperature change is probably the single biggest source

of error in optical sensors for oxygen [1, 2], because the phosphorescent materials deliver integral response

on simultaneously changed T– or O2– conditions. Temperature is known to affect (a) the phosphorescence

Q.Y. of the used dye, (b) the quenching constant(s), (c) the solubility of oxygen or (d) the diffusion of

oxygen [1]. On other hand, presence of even small (on level of ppm O2) amount of molecular oxygen will

modulate the response of the phosphorescence T–sensing system in a non-predictable manner.

The process of triplet-triplet annihilation upconversion (TTA-UC) relays on optically created densely

populated organic triplet ensembles, in which the inter-molecular energy transfer depends strongly on the

local molecular mobility (i.e. rotational diffusion (RF) and therefore on the local temperature). The increase

of RF leads to substantial increase of the emitter delayed fluorescence and simultaneously to decrease of the

residual sensitizer phosphorescence, creating the possibility for ratiometric all-optical temperature response

[3]. When the TTA-UC – active materials are embedded in singlet-oxygen scavenging matrix the material

response to small temperature and/or oxygen changes can be well distinguished. Simultaneous and all-

optical local temperature sensing and oxygen concentration sensing in water environment will be reported

and discussed.

References:

1. D. B. Papkovsky and R. I. Dmitriev, Chem. Soc. Rev., 2013, 42, 8700-8732. 2. X. Wang and O. S. Wolfbeis, Chem. Soc. Rev., 2014, 43, 3666-3761. 3. M. A. Filatov, S. Baluschev and K. Landfester, Chem. Soc. Rev., 2016, 45, 4668–4689. 4. F. Marsico, A. Turshatov, R. Peköz, Yu. Avlasevich, M. Wagner, K. Weber, D. Donadio, K. Landfester, S. Baluschev, and F. R Wurm., J. Am. Chem. Soc. 2014, 136, 11057−11064. Acknowledgments: The authors acknowledge the European Horizon 2020 Research and Innovation Programme

(grant agreement no. 732794, project HYPOSENS) for the financial support.


41



Multiscale modeling of spin-crossover phenomena in molecular materials

Jordi Cirera

Departament de Quimica Inorganica i Organica and Institut de Recerca de Quimica Teorica i

Computacional, Universitat de Barcelona, Barcelona, Spain

[email protected]

Switchable materials are a type of smart materials that undergo physical changes upon the exposure to

an external stimulus, therefore yielding to different applications such as sensing, molecular recognition or its

potential application in molecular electronic devices. Among them, spin-crossover (SCO) materials, in

which access to two alternative electronic states by means of the temperature (or other external stimulus) is

possible, are a prominent family due to the dramatic physical changes that the material undergoes upon

changing the spin-state of the metal center. The transition temperature (T1/2), a key physical property in the

characterization of SCO systems its usually hard to control, and therefore, the use of computational tools to

predict and rationalize its behavior will be of great help. In this presentation, we will present a

computational approach for the accurate calculation of T1/2 in SCO molecular systems. The trends for

several families of SCO, including [Fe(stpy)4(NCX)2] (X = S, Se, or BH3) or the unusual tetracoordinated

[PhB(MesIm)3Fe–N=PR3] SCO family will be presented.[1-4] Using the reported methodology, the

experimental trends observed will be fully rationalized in terms of the underlying electronic structure using

the corresponding molecular orbitals for each family. Furthermore, this approach can be used in a multiscale

approach, allowing for the construction of ab initio based force fields that can rationalize the experimental

trends for the T1/2 in condensed phase systems. This will be illustrated using as an example the water loading

effect over the T1/2 in the [Fe(pz)Pt(CN)4] Metal-Organic Framework material.[5-6]

References:

1. J. Cirera and E. Ruiz, Inorg. Chem., 57(2), 2018, 702 2. J. Cirera and E. Ruiz, Inorg. Chem., 57(22), 2018, 14097 3. J. Cirera and E. Ruiz, J. Mat. Chem. C, 3(30), 2015, 7954 4. J. Cirera and F. Paesani, Inorg. Chem., 51(15), 2012, 8194 5. J. Cirera, V. Babin and F. Paesani, Inorg. Chem., 53(0), 2014, 11020 6. C. Pham, J. Cirera and F. Paesani, J. Am. Chem. Soc., 138(19), 2016, 6123 Acknowledgments: CTQ2015-64579-C3-1-P, PGC2018-093863-B-C21, MDM-2017-0767


42



Evaluation of newly developed dye tags for proteins characterization and detection by

Fluorescence Correlation Spectroscopy

Stoyan Yordanov1, Aleksey Vasilev2, Martin Drucker3, Hans-Juergen-Butt1, Kaloian Koynov1

1Max Planck Institute for Polymer Research, Mainz, Germany

2Faculty of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria

3INRA – French National Institute for Agricultural Research, Colmar, France

[email protected]

Studying proteins, protein-protein and/or protein-virus interactions as well as their characterization and

detection in solution, in their native state, is difficult task. It is especially challenging if the proteins or

viruses under investigation are present in solution at low concentrations. In this case, Fluorescence

Correlation Spectroscopy (FCS) is a powerful tool to obtain quantitative information about the dynamic

behavior of the system and thus extract parameters such as diffusion coefficient, concentration, size

distribution, oligomeric state etc. However, to be able to apply FCS fluorescent labeling (with suitable dye)

of proteins is required. Covalent labeling can be very tedious and difficult task on its own. After such

labeling (if successful), one needs to purify the sample and remove remaining free dye. As a negative side

effect, some material can be lost in the process.

In order to facilitate protein characterization and detection we developed three red fluorescent dyes with

special features. Natively, if not bound to a protein or virus, each dye is in a dark state (non-fluorescent) or

exhibits low fluorescent yield when excited with light in aqueous buffer solution. However, upon binding to

a protein the fluorescence increases ca.10 fold or higher.

We used FCS and LSM (Laser Scanning Microscopy) to measure the affinity, efficiency and the

performance of the three sensor dyes for binding to globular (BSA and HSA), fibrillar (Amyloid beta 1-42,

related to Alzheimer disease) and viral proteins (related to CaMV virus assembly and transmission). We

show that at least two of these dyes are promising tool to use for direct fluorescence tagging of bio-

molecules without the requirement of purification.


43



Electron Microscopy and Multivariate Analysis for dynamical characterisation of

perovskite solar cells

G. Divitini


[email protected]

The use of perovskite materials (particularly methylammonium lead iodide) in solar cells has become very attractive due to the fast increase in reported power conversion efficiencies over the last few years, leading to values above 20%. While this value is competitive with established photovoltaic technologies, the stability of perovskite-based solar cells is still insufficient for commercial applications. In particular, it is very well known that some components, including the perovskite layer and the hole transporter, can degrade when exposed to a combination of heat and moisture. In situ TEM is an ideal tool for investigating such degradation and understanding the phenomena underpinning it. We carry out scanning TEM imaging and EDX elemental mapping as cross-sections from full-stack devices are heated in situ in the TEM [1]. To that aim we exploit recent advances in TEM-related technology, such as Silicon Drift Detectors (SDD) for EDX, which collect energy-dispersed X-ray spectra with a good yield, and stable MEMS heaters, enabling the temperature to be cycled quickly and reproducibly. Moreover, we employ multivariate analysis (principal component analysis, PCA) [2] to increase the signal-to-noise ratio of the spectral maps. We observe degradation processes that include decomposition of the perovskite film and ionic migration through the layers, and relate the degradation pathway to the fabrication conditions. References:

1. In situ observation of heat-induced degradation of perovskite solar cells - G. Divitini, S. Cacovich, F. Matteocci, L. Cinà, A. Di Carlo, C. Ducati, Nature Energy, 2016 2. Unveiling the Chemical Composition of Halide Perovskite Films Using Multivariate Statistical Analyses - Stefania Cacovich, Fabio Matteocci, Mojtaba Abdi-Jalebi, Samuel D. Stranks, Aldo Di Carlo, Caterina Ducati, Giorgio Divitini, ACS Appl. Energy Mater. 2018 Acknowledgments:

This work was supported by ERC under grants number 259619 PHOTO EM and 312483 ESTEEM2.


44



Luminescence properties of Gd1.97-xSmxTb0.03Mo3O12 for potential LED applications

M. Tsvetkov*, Ya.-K. Petrova, M. Milanova

Department of Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia

“St. Kliment Ohridski”, 1, J. Bourchier, 1164 Sofia, Bulgaria

[email protected]

Although the white LEDs (based on GaN and YAG:Ce) have been known and put into operation for a while

now, they suffer from few disadvantаges. The lack of red- emission gives rise to low color rendering index

(Ra<80) and high correlated color temperature (CCT≈7750K) that shifts the emitted light towards the blue

part of the spectrum [1]. One of the strategies to overcome these issues is to incorporate red- emitting

phosphor. In the present work we prepared series of solid solutions based on Gd1.97-xSmxTb0.03Mo3O12

(0.01<x<0.11) using conventional solid state reaction. The obtained samples were characterized by XRD

and TEM to confirm the crystal structure and phase homogeneity. UV-VIS and fluorescence spectroscopy

were used to investigate the optical and luminescence properties of the samples at room temperature. It was

found that the samples posses red emission at 601 nm and 645 nm typical for Sm(III) ions. The emission is

sensitive to Sm(III) concentration and the best obtained nanophosphor is the Gd1.92Sm0.05Tb0.03Mo3O12. The

fluorescence lifetime was also measured at room temperature and correlation between concentration and

lifetime was made.

References:

1. Bo Yuan et al., Physica B: Condensed matter, 550 (2018), 75-89 Acknowledgments: The financial support of the Sofia University Fund via Project 80-10-

153/16.04.2019 is highly appreciated.


45



Assessment of the Bulgarian wastewater treatment plants impact on the receiving

water bodies

Galina Yotova, Veronika Mihaylova, Boika Zlateva, and Stefan Tsakovski

Chair of Analytical Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia “St. Kl. Okhridski”,

1, J. Bourchier Blvd., 1164 Sofia, Bulgaria

[email protected]

Deterioration of water quality is a major problem world widely according to many international non-

governmental organizations. As one of the European Union (EU) countries, Bulgaria is obliged by EU

legislation to keep up to best practices in assessing surface waters quality and efficiency of wastewater

treatment processes. For these reasons studies were undertaken to utilize both ecotoxicological (Microtox®,

Phytotoxkit FTM, Daphtoxkit F) and instrumental tests (to determine pH, electrical conductivity (EC),

chemical oxygen demand, total suspended solids (TSS), total nitrogen and phosphorus, chlorides, sulphates,

Cr, Co, Cu, Cd, Ba, V, Mn, Fe, Ni, Zn, Se, Pb) as well as and advanced chemometric method (partial least

squares - discriminant analysis (PLS-DA)) in data evaluation to comprehensively assess wastewater

treatment plant (WWTP) effluents and surface waters quality around 21 major Bulgarian cities. The PLS-

DA classification model for the physicochemical parameters gave an excellent discrimination between

WWTP effluents and surface waters with 95.16% correct predictions (with significant contribution of EC,

TSS, P, N, Cl, Fe, Zn and Se). The classification model based on ecotoxicological data identifies the plant

test endpoints as having greater impact on the classification model efficiency than bacterial or crustaceans’

endpoints studied.

The methodology proposed in the presented study combines original sampling scheme and appropriate

supervised pattern recognition technique and offers:

• new way for WWTPs impact assessment on receiving water bodies;

• prioritization of water quality indicators concerning WWTPs impact on receiving water bodies;

• opportunity for selection of optimal water quality indicator set for assessment of WWTPs impact.

Acknowledgments: The support of H2020 programme of the European Union (project ID: 692146-H2020-eu.4.b

“Materials Networking”) is gratefully acknowledged


46



Interfacial layers of volatile surfactants: adsorption and kinetics of evaporation

T. D. Gurkov, R. D. Stanimirova, R. I. Uzunova, K. D. Danov, and P. A. Kralchevsky

Department of Chemical and Pharmaceutical Engineering (DCPE), Faculty of Chemistry and Pharmacy at

the University of Sofia, James Bourchier Avenue 1, Sofia 1164, Bulgaria

[email protected]

In this work we characterize the adsorption at air/ water interface when the system contains a volatile surfactant, and consider the effect of evaporation on the surface tension as a function of time. The study is focused on substances whose characteristic features are (i) appreciable water solubility, (ii) relatively high vapor pressure, and (iii) significant surface activity – we use linalool, benzyl acetate, and citronellol, as volatile amphiphiles (VA). The adsorption is quantified by measuring the surface tension kinetics, (t), at different bulk concentrations using the Maximum Bubble Pressure Method; the data are extrapolated to equilibrium, and fitted with the van der Waals equation of state. Under these conditions there are no effects of evaporation, and we obtain the „isotherm” – the relation between , the adsorbed ammount per unit area, , and the bulk concentration, sc . The case when evaporation takes place is studied using drop shape analysis, with sessile

drops made from surfactant solution, and with pendant drops whose surfaces had been pre-equilibrated in vapors of the volatile amphiphiles (VA). Under the conditions of evaporation, the surface tension is found to increase (see Fig. 1). Theoretical model is proposed for description of this dependence; the balance of fluxes at the interface is taken into account, with the rate-determining process being the diffusion through the boundary layer at the gas side. The mass transport kinetics is combined with the isotherm (the )( sc

relation), to yield a theoretical prediction for )(t . Following the above procedures, we achieve very good agreement between the calculations and the experiment (Fig. 1). As an adjustable parameter, one material constant is determined – the mass transfer coefficient for VA across the A/W boundary. Results for different VA are presented. Fig. 1. Comparison between experimental and theoretical increase of surface tension when benzyl acetate (BA) is left to evaporate from a pendant drop whose surface has been preliminarily equilibrated in saturated vapors of pure liquid BA. Acknowledgements: The authors are grateful for financial support, in part from the Horizon 2020 project ID: 692146-H2020-eu.4.b “Materials Networking”, and in part from the project #DO 02/4 – 12.06.2018 with the Bulgarian Science Fund (FNI).

BA – evaporation from saturated A/W layer

time, s

0 240 480 720 960 1200

su

rface t

en

sio

n,

mN

/m

56

60

64

68

72

Measured-2

Measured-1

Calculated


47



Microfluidic fabrication of micro polymer inclusion beads (µPIBs). Application to the

recovery of gold from electronic scrap

Yanlin Zhang, Robert W. Cattrall and Spas D. Kolev

School of Chemistry, The University of Melbourne, Victoria 3010, Australia

[email protected]

A novel composite material in the form of micro polymer inclusion beads (µPIBs) consisting of poly(vinyl

chloride) as the base-polymer and Aliquat 336, a mixture of quaternary alkylammonium chlorides, as the

extractant, was fabricated using a microfluidic technique previously used by us for the manufacturing of

polymer microspheres1. The size and morphology of the µPIBs were examined using optical microscopy and

scanning electron microscopy, respectively. Their composition was optimized in term of extraction

performance. The newly developed µPIBs were applied to the extraction of Au(III) from its acidic aqueous

solutions which could be stripped completely using thiourea. A proof of concept was provided for the

selective recovery of Au(III) from an acidic aqueous solution with a composition mimicking that of aqua

regia digests of electronic scrap.

References:

1. Y Zhang, RW Cattrall, SD Kolev, A fast and environmentally friendly microfluidic technique for the fabrication of polymer microspheres, Langmuir 33 (2017) 14691−14698


48



Inkjet printing of direct carbon solid oxide fuel cell

R. I. Tomova, M. Dudekb R.V. Kumara

a Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road,

Cambridge, CB3 0FS, United Kingdom b AGH University of Science and Technology, Faculty of Fuels and Energy, Krakow, Poland

[email protected]

After being neglected for almost two centuries, the Direct Carbon Fuel Cells (DCFCs) have recently attracted a renewed interest. This is mostly due to the prospect of using abundant solid carbon reserves with a high efficiency of power generation (up to 80%) - compared to traditional coal-fired power plants which have efficiencies of ~40% - with an option for direct CO2 product capture. DCFCs offer additional benefits of economically feasible conversion of carbonaceous solids from a variety of different sources (coal, biomass, coke, municipal solid waste etc.) directly to electric power employing an existing and well established delivery infrastructure and traditional storage methods.

Iinkjet printing of ceramic suspensions was proven to be feasible technology for the fabrication of electrolyte supported Direct Carbon Solid Oxide Fuel Cells SOFCs (DC-SOFCs). The inkjet printing (IJP) fabrication allowed for easy modification of the anode coatings including thickness control, porosity graduation and precise infiltration with catalytically active materials. The comparative tests showed similar performances for screen printed (thick anode - ~ 50 µm) and inkjet printed (thin anode ~ 10 µm) cells with typical peak power density of ca. 100 mW cm-2 at 800C. The replacement of 8YSZ with doped ceria in the anode was shown to cause substantial increase in the maximum output power. It was also demonstrated that infiltration of the anode by inkjet printing of sol inks (CuNiO3) can lead to an overall improvement in DC-SOFC’ performance related to alteration of the internal gasification processes.


49



Bicontinuous phases from mixed surfactant solutions with enhanced solubilization

capacity and their potential applications

Mihail Georgiev, Lyuba Aleksova, Krassimir Danov, Peter Kralchevsky

Department of Chemical & Pharmaceutical Engineering,

Sofia University, Sofia 1164, Bulgaria

[email protected]

Nowadays, the control of viscosity of mixed solutions of anionic and zwitterionic surfactants by the

addition of NaCl is well known and has found numerous applications in personal care formulations (such as

shampoos, hair-conditioners, and body-washes) and in home-care formulations (dish-washing and liquid

laundry concentrates) as well. However, there is no information about the effect of divalent ions on such

surfactant mixtures. In this work, we investigate the impact of three divalent salts ZnCl2, MgCl2, and CaCl2

on the phase behavior and rheology of the mixture of sodium lauryl ether sulfate (SLES-1EO) and

Cocamidopropyl betaine (CAPB). In the course of our study, in a specific range of compositions, we

observed phase separation. In the case with MgCl2, a denser and viscous phase separates from the aqueous

solution on the bottom of vials. With Zn2+ and Ca2+, we observed the formation of small droplets in bulk,

which very slowly sediment but do not form a separate consolidated phase. Moreover, the droplets in the

systems with Zn2+ have non-spherical form.

Experiments with oil-soluble and water-soluble dyes indicate that the separated phase is bicontinuous.

It possesses very high solubilization capacity for hydrocarbons of medium chainlength (C8-C12), which

could be useful in various applications.

Acknowledgment: The authors gratefully acknowledge the support from the National Science Fund of Bulgaria, Grant No. DN 09/8/2016.


50



NHC-ligands: Imidazopyridine-3-ylidenes versus Imidazoquinoline-1-ylidenes

Rumen Lyapchev 1a, Rositsa Kostandieva 1, Luben Borislavov 1, Petar Petrov 1, Miroslav Dangalov 2,

Nikolay G. Vassilev 2 1 Department of Organic Chemistry, Faculty of Chemistry and Pharmacy, Sofia University St. Kliment

Ohridsky, 1, James Bourchier Blvd., 1164, Sofia, Bulgaria

2 Institute of Organic Chemistry with Center of Phytochemistry, Bulgarian Academy of Sciences, Acad. G.

Bonchev Str. Bl. 9, 1113 Sofia, Bulgaria

[email protected]

Despite the wide variety of different types of NHC structures, there is almost no information for the

electronic properties and the catalytic performance of imidazopyridine-3-ylidene (A) and imidazoquinoline-

1-ylidene (B) carbene ligands.

Herein we present synthesis of palladium complexes bearing carbene ligand with condensed phenyl

(A1) or naphthalene (B1) system. These complexes were tested in model Suzuki reaction.

Selenoureas (A2 and B2) were synthesized and analyzed by 77Se NMR spectroscopy to evaluate the π-

acceptor ability of the new ligands.

Acknowledgments:The authors acknowledge the program “Young scientist and Postdoctoral candidates” MCD №577/17.08.2018 for the support.



51



Ionic liquids as alternative solvents in the sample treatment for determination of

biologically active compounds in plants

Ivan Svinyarov, Milen G. Bogdanov

Faculty of Chemistry and Pharmacy, Sofia University “St. Kl. Ohridski”, Sofia, Bulgaria

[email protected]

The majority of methods for quantification of natural products (NPs) are based on High Performance Liquid

Chromatography (HPLC), which employ organic solvents, such as methanol, diethyl ether, chloroform, etc,

to perform the sample preparation step. All these solvents, however, are highly volatile, flammable and

toxic, which is in a contradiction with the widely accepted nowadays twelve principles of the Green

chemistry. In particular, according to the 5th principle, the use of safer auxiliary substances (e.g. solvents,

separation agents, etc.) is rather preferable to the harmful ones in the laboratory practice.

Ionic liquids (ILs) consist of charge-stabilised organic cation and inorganic or organic anion. They

are liquids at temperatures below 100 °C and display a wide range of unique properties, such as negligible

vapor pressure, non-flammability, high thermal stability, low chemical reactivity, etc. The above mentioned

features, together with their fine tunable physicochemical properties, favor ILs application as extractants of

NPs from their native sources.1

Following the above mentioned general trends we studied the performance of a wide variety of ILs in

the sample preparation step for determination of NPs of industrial interest, e.g. glaucine, galantamine and

valerenic acids. All possible influential factors were comprehensively investigated, optimal conditions for

quantitative extraction of the target NPs were found and safer HPLC methods for determination were

developed and validated. The methods proposed avoid the use of organic solvents, while ensure quantitative

yields, the latter suggesting their high potential for industrial application.

References:

1. M.G. Bogdanov, Ionic liquids as alternative solvents for extraction of natural products, in: F. Chemat, M. Abert

Vian (Eds.), Alternative Solvents for Natural Products Extraction, Green Chemistry and Sustainable Technology,

Springer-Verlag, Berlin Heidelberg, 2014, pp. 127–166.

Acknowledgments: The financial support of the National Science Fund of Bulgaria at the Ministry of Education and

Science (project DFNI T 02/23), as well as the contribution of Horizon2020 program of the European Commission

(project Materials Networking, ref. no. 692146) is greatly acknowledged by the authors.


52



Stability or photoactivity? Properties of realistic TiO2 nanoparticles

Ángel Morales-García,a Antoni Macià,a Stefan T. Bromley,a,b Francesc Illasa

aDepartament de Ciència de Materials i Químia Física & Institut de Química Teórica i Computacional

(IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1-11, 08028 Barcelona, Spain

bInstitució Catalana de Recerca i Estudis Avançats (ICREA) Passeig Lluis Companys 23, 08010 Barcelona,

Spain

[email protected]

Hydrogen constitutes an ideal green fuel but so far it is mainly obtained from fossil resources. Water

splitting using TiO2 as a photocatalyst constitutes an alternative although its practical use under visible

sunlight is hindered from the too large “band gap” of the known forms of this oxide. Suitable modifications

have been proposed including doping and/or nanostructuring. Nevertheless, finding a practical solution

without a deep knowledge of how the properties of TiO2 nanoparticles evolve with size, shape and

morphology seems to be an insurmountable task. To make progress in this direction, a systematic study has

been carried out regarding the relative stability and properties of differently shaped realistic (TiO2)n

nanoparticles containing explicitly up to 1785 atoms or 595 formula units.1 Using all electron, relativistic,

density functional theory-based calculations with accurate numerical orbital centered basis sets, we

investigated the relative stability of spherical and faceted nanoparticles as a function of size. A crossover

between faceted and spherical morphology is found at ~100 TiO2 units where the faceted nanoparticles

become more stable than the spherical ones. The present study provides compelling evidence that for

stoichiometric nanoparticles of realistic size, a faceted morphology is preferred although spherical shaped

ones tend to exhibit smaller optical gap. Therefore, the successful synthesis of spherical nanoparticles, often

showing better photocatalytic activity, has to be attributed to the particular route used able to stabilize these

energetically metastable structures. The present study suggests that controlling kinetic of particle growth

rather than thermodynamic stability is the key towards TiO2 nanoparticles with better photocatalytic activity

under sunlight.

References:

1. Á. Morales-García, A. Macià, F. Illas, S. T. Bromley, Nanoscale 2019, 11, 9032-9041. Acknowledgments: Spanish MINECO/FEDER (CTQ2015-64618-R), Spanish MICIU (MDM-2017-0767, IJCI-2017-

31979), Generalitat de Catalunya (2017SGR13), PRACE (EXCIPHOCAT 2016163940). ICREA Academia Award.



53



Inclusion complexes of naproxen in amorphous gamma cyclodextrin

Hristo Veselinski, Tsveta Sarafska, Stiliyana Pereva, Veselin Petrov, Tony Spassov

Address: 1164 Sofia, 1 James Bourchier Blvd.

[email protected]

Cyclodextrines are cyclomalto-oligosaccharides, consisting of a macrocyclic ring of glucose subunits joined

by α-1,4-glycosidic bonds. These structures are in the shape of a truncated cone, the outer part of which has

hydrophilic nature, while a hydrophobic cavity is formed inside. These structural features of cyclodextrins

allow the inclusion of a large number of drug substances in their hydrophobic cavities, forming “host-guest”

complexes. Gamma-cyclodextrin (γ-CD) is a cyclic oligosaccharide formed by bacterial digestion of starch

and is used as a solubilizing agent and stabilizer in various pharmaceutical and food products. Like other

cyclodextrins, γ-CD can form water-soluble inclusion-complexes with otherwise very poorly soluble

compounds. Compared to natural α-CD and β-CD, γ-CD has the largest hydrophobic cavity, the highest

water solubility and the most favorable toxicological profile.

The goal of the present study is the possibility of increasing the solubility of naproxen (characterized by

very low water solubility causing undesirable gastric reactions) by forming a complex with amorphous-γ-

CD. For this purpose amorphous-γ-cyclodextrin is obtained and is structurally and thermally characterized.

“Host-guest” type of inclusion complexes were obtained between crystalline and amorphous-gamma-

cyclodextrin and naproxen, and the degree of inclusion of the complexes obtained by various techniques was

determined by differential scanning calorimetry. The structure and microstructure of the complexes was

determined by scanning electron microscopy. To prove the complex formation in the final products, X-ray-

diffraction analysis and IR spectroscopy were used.


54



SHORT ORAL PRESENTATIONS


55

Horizon 2020 Project “Materials Networking” SO1 “Advanced Materials” Workshop


Polymer-grafted gold nanoflowers with temperature-controlled catalytic features by

combining ARGET ATRP and metal reduction in one pot

Chaojian Chen,1,2 David Yuen Wah Ng*1 and Tanja Weil*1,2 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.

2Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.

[email protected]

We report a convenient strategy for the construction of polymer-grafted gold nanoflowers by combining

activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and the

reduction of metal ions in a one-pot fashion. The approach is based on a protein-derived biopolymer

template providing (1) distinct numbers of amino groups able to bind chloroauric anions and (2) many

initiation sites for ARGET ATRP. Poly(N-isopropylacrylamide)-coated gold nanoflowers (PNIPAM-

AuNFs) with controllable sizes, shapes, and shell thickness are obtained and applied as temperature-

controlled nanoparticle catalysts for the hydrogenation of p-nitrophenol.

The combination of in-situ particle growth and polymerization represents a novel and facile approach

for the preparation of polymer-metal nanocomposites. Compared to conventional methods involving

nanoparticle synthesis, purification and post-modification, in-situ growth allows the convenient synthesis of

polymer-coated metal catalysts without any further reaction and tedious purification steps. More

significantly, smart polymers formed during the polymerization process provide additional in situ control

over the formation of metal nanostructures, which has not been achieved yet. We believe the novel strategy

can be expanded to other noble metal nanoparticles and functional polymers, providing access to a variety of

multifunctional polymer-metal hybrid nanomaterials for broad applications such as sensing, catalysis,

controlled drug delivery, and photothermal therapy in the near future.

References:

1. C. Chen, D. Y. W. Ng, T. Weil, Polymer-grafted gold nanoflowers with temperature- controlled catalytic features by in-situ particle growth and polymerization, Mater. Chem. Front. 2019, accepted.

Acknowledgments: The authors acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG,

German Research Foundation) – Project number 213555243 SFB 1066 (A06). C.C. is grateful for a doctoral

fellowship from Promotionskolleg Pharmaceutical Biotechnology of Ulm University funded by the state of Baden-

Württemberg.


56



Solvation-desolvation thermodynamics in mixed alkaline-ion batteries

Hristo Rasheev1, R. Stoyanova2, Alia Tadjer1 1Faculty of Chemistry and Pharmacy, University of Sofia

2Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences

[email protected]

Developing batteries has always been a challenge but this is even more so nowadays when we are

dependent on them in most of our daily activities. Among the main components of batteries, the most

attention is dedicated to the electrodes and the electrolytes, for which elaborate theories are applied, while

the choice of solvent is rather a matter of trial-and-error.

The molecular modelling allows deeper insight into the interactions of electrolyte components and

solvent molecules in the charge-discharge process. Particularly in the case of alkaline-ion batteries, the metal

ions change continuously their solvation status starting from none in the electrodes, gradually acquiring a

solvation shell in the bulk of the solution and stripping it off subsequently before intercalating in the other

electrode. All these stages can be simulated and characterised by means of various molecular descriptors

using an assortment of theoretical methods.

In the present study, the free energy of clusters of single-cation- and mixed-cation pairs with

increasing/decreasing number of explicit solvent molecules in the gas phase and in implicit solvent is

estimated quantum-chemically in order to gain knowledge about: i) the preferred coordination number of the

metal ions; ii) the charge transfer between metal ions and solvation shell; iii) the competition between the

cations in batteries utilizing a dual-cation electrolyte. The cations considered are Li+, Na+, and Mg2+

(neutralized by PF6ˉ) and the solvent is ethylene carbonate.

The results obtained will provide guidelines for enhancement of the performance of mixed-cation

electrolytes as compared to the single-cation ones.

Acknowledgments: The research was funded by projects NRF D09/13/2016, SU-RF 80-10-155/2019 and the National

Research Program E+, grant D01-214/28.11.2018.



57



Extending the carbazole core towards enhanced organic semiconductors

Roger Bujaldón and Dolores Velasco

Grup de Materials Orgànics, Institut de Nanociència i Nanotecnologia (IN2UB), Departament de Química

Inorgànica i Orgànica, Secció de Química Orgànica, Universitat de Barcelona, Barcelona, Spain.

[email protected]

Carbazole-based semiconductors have been gradually setting as important materials within the

optoelectronic technology.1 Indeed, carbazole stands as a very promising building block for constructing

novel organic semiconductors with effective charge carrier transport. Moreover, derived structures such as

indolocarbazole and triindole, show high thermal stability, π-stacking capability and optoelectronic

properties.2 Thus, they have been targeted by our research group both synthetically and in terms of

application in vacuum-deposited Organic Thin-Film Transistors (OTFTs). Specifically, this study is centered

on the design and preparation of π-extended carbazole-based cores, which go from triindole to the novel

diindolocarbazole, and several functionalized derivatives. In fact, a key factor is the attachment of alkylic

moieties, since the position and length of the alkyl chains affect the intermolecular organization, and thus,

the charge-transporting properties of the thin films.3 Alongside the characterization of their optoelectronic

properties, the integration in OTFTs with different organic dielectrics has confirmed the potential of this

new family of materials.

References:

1. X.-C. Li, C.-Y. Wang, W.-Y. Lai, W. Huang, J. Mater. Chem. C 2016, 4, 10574.

2. M. Reig, J. Puigdollers, D. Velasco, J. Mater. Chem. C 2015, 3, 506.

3. M. Reig, G. Bagdziunas, A. Ramanavicius, J. Puigdollers, D. Velasco, Phys. Chem. Chem. Phys. 2018, 20, 17889.

Acknowledgments: Financial support from the Ministerio de Economía y Competitividad (Spain, grant CTQ2015-

65770-P MINECO/FEDER) is gratefully acknowledged.


58



Surface and foam properties of nonionic surfactant solutions

at high sugar concentration

Fatmegyul Mustan,a Nadya Politova,a Zahari Vinarov,a

Slavka Tcholakova,a Damiano Rossetti,b Pip Raymentb

aDepartment of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia

University, 1 J. Boucher Ave., 1164 Sofia, Bulgaria

bUnilever R & D, Colworth, UK

[email protected]

Characterization of the surface and foam properties of the amphiphilic molecules which possess high surface

activity is very important from the view point of their practical application in different formulations. One of

such type of molecules is alkyl esters and ethers which are a focus point in our study. Series of esters and

ethers with different hydrophilic groups in wide range of hydrophilic-lipophilic balance (HLB) values are

investigated. The surface properties of their aqueous solutions in presence of high sucrose concentration are

studied in terms of adsorption kinetics and surface elasticity determined upon slow compression of the

surface layer. Their foamability and foam rheology are also studied.

By the optical observations it is found that the hydrophobic surfactants (hydrophilic-lipophilic balance

<11) form different in shape and in size vesicles inside the solutions depending on their hydrophilic head

group. From the surface properties characterization is obtained that the presence of vesicles inside the

solutions is responsible for the formation of condensed adsorption layers which give very high surface

elasticity several hundreds mN/m and very high (>30 mN/m) surface stress upon slow deformation. The

values for both surface and foam rheology of the hydrophilic ones, which do not form any entities inside the

solution, are much lower. But foams with very small bubbles in size and high yield stress are produced with

hydrophobic substances. The results from both types of experiments show very good correlation between the

rheological behavior of the adsorption layers and foams stabilized by these layers.


59



Physico-chemical properties of L-Asp based Gemini surfactants

Kristina M. Mircheva1, Nikolay A. Grozev 1, Borislav A. Anchev2, Daniela S. Tsekova2,

1-University of Sofia, Faculty of chemistry and pharmacy, Dept. of Physical Chemistry.

2 - University of Chemical technology and Metallurgy, Dept. of Organic Chemistry.

[email protected]

Two types of molecules containing L-Asp were synthesized – gemini (A6Nx) with hydrocarbon tail

length (x= 6, 10 and 14) and a spacer of 6 methylene groups (A6), and “monomers” (mA6Nx) with

hydrophobic tail and a spacer. Two series of each type are obtained - with and without benzyle group

(A6NxC).

In a previous study it was found that these compound were water insoluble. They form monolayers at the

air-water interface. By means of BAM and AFM the presence of some fibril-like structures were observed.

In the present work we study the sodium salts of the aforementioned surfactants (A6NxC) which are

readily water soluble. The critical aggregation concentrations of these compounds were evaluated by

measuring the surface tension and the conductivity of their aqueous solutions.

In order to understand the nature of the aggregates preliminary observations were performed. The

aggregates formed after the evaporation of deposited drop of solution on a glass or silica plate are studied by

means of optical microscopy technics. It should be stressed that gemini molecules do not form visible

structures in the bulk of the drop. In this case aggregates are formed after the evaporation. In the case of the

“monomers” – the form aggregates in both in the bulk of the drop and after the evaporation process had

finished.



60



A DFT/PCM study of the complexation between Ga3+ and ribonucleotide reductase substrates

Nikoleta Kircheva and Todor Dudev

Faculty of Chemistry and Pharmacy, Sofia University, 1164 Sofia, Bulgaria

[email protected]

[email protected]

The abiogenic gallium, administered in the form of soluble gallium salts, is used to fight neoplastic formations. The broadly accepted mechanism of its action postulates the inactivation of the upregulated/hyperactive enzyme ribonucleotide reductase (RNR) in cancer cells by substituting the redox-active iron by redox-silent gallium in the enzyme active site. Recently, another hypothesis for the Ga3+ therapeutic action has been put forward: The metal cation can deactivate the enzyme by entrapping its substrates (nucleotide diphosphates; NDPs) into Ga3+-NDP complexes lowering in such a way the free substrate levels in the cell. Several outstanding questions, related to this hypothesis, arise: Does gallium readily form complexes with NDPs? What are the preferable modes (monodentate or bidentate) of metal binding to NDPs? How does the metal complexation with NDP depend on the type of nucleobase and dielectric properties of the environment? Does, and if so, to what extent, the metal binding alter the native conformation of the substrate thus influencing the process of substrate-enzyme recognition? Here, by employing an integrated DFT/PCM approach, we attempt to answer these questions and shed light on the intimate mechanism of gallium’s therapeutic action. The calculations, which are in line with the available experimental data, lay support (for the first time) to the recent hypothesis about the curative effect of gallium, revealing that, by engaging the free NDPs in forming metal complexes, on one side, and producing metal constructs that are not/poorly recognizable by the host enzyme, on the other, gallium deprives RNR from its substrates, thus reducing the enzyme activity in malignant cells.

References:

1. “Novel insights into gallium’s mechanism of therapeutic action: a DFT/PCM study of the interaction between Ga3+ and ribonucleotide reductase substrates”, recently accepted for publication in J. Phys. Chem B




61



Fe-based MOFs as efficient catalysts for the degradation of emerging contaminants in

urban wastewater

Zhihong Ye, Enric Brillas, Francesc Centellas, Pere L. Cabot, Ignasi Sirés Laboratori d’Electroquimica dels Materials i del Medi Ambient, Seccio de Quimica Fisica, Facultat de

Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain

[email protected], [email protected]

The occurrence of emerging contaminants in the environment has become a global challenge intimately

linked to climate change. Their vast and expanding usage has raised great awareness worldwide because of

their toxicity, persistence, bioaccumulation and long-range transport [1].

Metal organic frameworks (MOFs) have attracted substantial attention in recent years as ordered porous

materials with extensive applications embracing gas storage, separation, fuel cells, catalysis and

environmental preservation. Among numerous MOFs applied for the abatement of organic pollutants, iron-

containing MOFs are particularly interesting due to their potentially excellent catalytic ability to promote

Fenton’s reaction [2].

Fenton-based electrochemical advanced oxidation processes (EAOPs) have been proven efficient and

promising technologies for the treatment of wastewater containing recalcitrant and toxic emerging

contaminants. However, their use in practice is limited owing to several drawbacks such as the requirement

of acidic pH conditions and production of iron sludge. In this study, iron-containing MOFs or their

derivatives were introduced as heterogeneous electro-Fenton (EF) or photoelectro-Fenton (PEF) catalysts for

the first time to overcome those drawbacks and treat various contaminants in urban wastewater. Specifically,

FeS2/C nanoparticles, fabricated by sulfidation and carbonization of an Fe-MOF precursor, Fe@C-N,

derived from NH2-MIL 88B, and a 2D MOF, Fe-bpydc, were developed and applied in EAOPs. Their

unique mesoporous structure conferred a great degradation performance to EF and PEF processes.

References:

1. J.Q. Jiang, Z. Zhou, V.K. Sharma, Microchem. J. 110 (2013) 292–300. 2. V.K. Sharma, M. Feng, J. Hazard. Mater. 375 (2019) 3–16.

Acknowledgments:

The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU). The PhD scholarship awarded to Z. Ye (State Scholarship Fund, CSC, China) is also acknowledged.


62



Correcting flaws in the assignment of nitrogen chemical environments in N-doped graphene

Marc Figueras†, Ignacio J. Villar-Garcia‡, Francesc Viñes†, Carmen Sousa†, Vcitor A. de la Peña O’Shea‡,

and Francesc Illas†

†Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional

(IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain

‡Photoactivated Processes Unit, IMDEA Energy Institute, Parque Tecnológico de Móstoles, Avda. Ramón

de la Sagra 3, 28935 Móstoles, Madrid, Spain

[email protected]

X-ray photoelectron spectroscopy (XPS) applied to N-doped graphene leads to a rather broad N(1s) core

level signal that, based on different sources available in the literature, is most often interpreted by fitting the

experimental spectra to three peaks, see Figure 1. The resulting N(1s) features are assigned to graphitic,

pyrrolic, and pyridinic nitrogen, even if these are far from being uniquely defined in the literature. This

broadly accepted interpretation has been questioned by recent accurate Hartree–Fock calculations

concluding that graphitic and pyrrolic N(1s) core level binding energies are too close to be distinguished,

and therefore, a more sensible fit is first-principles guided towards two peaks.


63



First principles evaluation of the initial oxidation

of transition metal surfaces

Anabel Jurado-Mañas,* Francesc Viñes

Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional de

la Universitat de Barcelona (IQTCUB),c/ Martí i Franquès 1-11, 08028 Barcelona, Spain

[email protected]

Transition Metals (TM) are key materials in many research fields, including heterogeneous catalysis,

electrocatalysis, and nanotechnology, mostly due to their properties, including the moderate chemical

activity of late TMs surfaces, and a generally good malleability, and electrical and thermal conductivities.

The TM properties can be greatly affected when oxidized, e.g. having a reduced chemical activity, fragility,

and a semiconductor/insulator behavior. It is crucial to understand the thermodynamic stability of oxygen on

such TM surfaces from an atomistic point of view so as to foster/avoid such an oxidation. The present work

explores the atomic O interaction on 81 low index Miller surfaces of 27 TMs, by Density Functional Theory

(DFT) 1 simulations on slab models, including the possible preference on surface or incorporated subsurface.

The results are used to gain phase diagrams of O stability in terms of working temperature, T, and O2 partial

pressure, PO2, see Figure, by exploiting the Ab Initio Thermodynamics (AIT) approach.2

References:

1. J. P. Perdew, K. Burke, M. Ernzerhof, Generalized Gradient Approximation made Simple. Phys. Rev. Lett. 77

(1996) 3865.

2. J. Rogal, K. Reuter, Ab Initio atomistic thermodynamics for surfaces: A primer. Educational notes (pp. 2-1–2-18)

RTO-EN-AVT-142, Paper 2.



64



Triple stimuli-responsive interpenetrating polymer network of

poly(carboxybetaine methacrylate)/poly(sulfobetaine methacrylate) Konstans Ruseva1, Radostina Alexandrova2, Maya Argirova3, ElenaVassileva1

1Laboratory on Structure and Properties of Polymers, Department of Pharmaceutical and Applied Organic

Chemistry, Faculty of Chemistry and Pharmacy, Sofia University ”St. Kl. Ohridski”

2Institute of Experimental Morphology, Pathology and Anthropology, Bulgarian Academy of Sciences

3Department on Burns and Plastic surgery, Pirogov Hospital, 21, Totleben blvd., 1606 Sofia, Bulgaria

[email protected]

Stimuli-responsive or ‘‘smart’’ polymers exhibit large and sharp changes in their physical and/or chemical

properties in response to small external stimuli. They have been considered very useful in many fields such

as chemical and mechanical engineering systems, as temperature or pH indicators, as well as biomaterials

and drug delivery systems.

Interpenetrating polymer networks (IPNs) are polymer materials comprising two or more networks that are

at least partially entangled on a molecular scale but not covalently bonded to each other and cannot be

separated unless chemical bonds are broken. The formation of IPN structures is an effective way to improve

and enrich the properties of single polymer networks and their hydrogels due to the additive effect of the

IPNs components. Thus, it is possible to tailor the IPNs characteristics in order to achieve specific properties

by an appropriate control on their composition.

The present work reports the synthesis of an entirely zwitterionic “smart” IPN consisting of

poly(carboxybetaine methacrylate) (PCB) and poly(sulfobetaine methacrylate) (PSB). As PCB is pH

responsive and PSB is thermoresponsive, it was interesting to study if their joint IPN is able to intelligently

respond upon changes of these two external stimuli. Furthermore, as both PCB and pSB are also salt-

responsive due to their anti-polyelectrolyte behavior, we expected the joint PCB/PSB network to exhibit

simultaneous triple responsiveness. Our results confrmed the expectations and here we report the succesful

developemеnt of a triple responsive polymer based material which shows changes in its properties upon

changes in pH, temperature and salt. This makes the newly developed PCB/PSB IPNs a unique material

exhibiting triple responisve behaviour towаrds three “bilogical” stimuli, namely temperature, pH and salt

cocnentration. The inherent bicompatibility of zwitterionic polymers was also demonstarted via cytotoxicity

tests.

Acknowledgments: The financial support received by the Bulgarian National Science Foundation, Grant DFNI T-02-

15/12.12.2014 and the program “Young scientists and Postdoctoral candidates” of the Bulgarian Ministry of Education and

Science, MCD № 577/17.08.2018 is highly appreciated.


65



Synthesis and characterization of nanostructured Pt-Ag-based chalcogenidesemiconductors

Mengxi Lin, Albert Figuerola

University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain

[email protected]

Platinum-based chalcogenides have been gaining a lot of attention due to the special electrical and catalytic

properties stemming from both the platinum presence and the semiconductor nature of the

material.1Colloidal chemistry approaches are found to be a perfect candidate to form homogenous and

compositionally complex nanostructured systems.2In this work, the silver selenide nanoparticles (NPs) are

used as starting materials due to their high conductivity and super-ionic characteristic3to explore the

possibility of partial cation exchange reaction between Pt and Ag cations from the host lattice of Ag2Se

NPs. Thus, a set of synthesis were designed by changing reaction parameters such as temperature, amount of

reactants and alsovarieties of capping agentsin order to form suchnanostructured systems. The

characterization results suggested that the silver chalcogenide nanocrystalshave successfully transformed

into compositionally more complex systemsby using oleylamineas capping agent at certain temperaturesby

means of cation exchange reaction. Structural and chemical characterization of these novel system suggests

the formation of a ternary material with a Ag3PtSe2stoichiometry

References:

1.Chia, X. et al., Adv. Funct. Mat.2016, 26(24), 4306–4318

2. Costi, R. et al., Angew Chem. Int. Ed. 2010, 49(29), 4878–4897

3.Simon, R. et al., Adv. Energ. Conv. 1963, 3(2),481-505

Acknowledgments:

We acknowledge financial support from the Spanish MINECOthrough CTQ2012-32247, CTQ2015-68370 P,and

ENE2015-63969-R and from the Generalitat de Catalunya through 2014SGR 129.



66



Two dimensional Transition Metal Carbides/nitrides (MXenes) as potential catalysts

for CO2 conversion to CO

Raul Morales-Salvador1,*, Daniel Gouveia2, Ángel Morales-García1, Francesc Viñes1, José R.B Gomes2, and

Francesc Illas1

1 Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional

Universitat de Barcelona (IQTCUB), Martí i Franquès 1-11, 08028, Barcelona, Spain.

2CICECO, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193

Aveiro, Portugal

[email protected]

Carbon dioxide (CO2) is one of the main actors of the greenhouse effect and its removal from the

atmosphere is becoming an urgent need. CO2 capture and storage (CCS) and usage (CCU) technologies are

intensively investigated to decrease CO2 concentration in the atmosphere. Both CCS and CCU require

appropriate materials to adsorb and activate CO2. Inspired by the promising results on Transition Metal

Carbides (TMCs), it has been found that a recently reported family of 2D TMC materials, called MXenes,

can be potentially useful in CCS technologies, later on experimentally confirmed1.

Here we investigate the CCU possibilities by MXene within computational simulations based on Density

functional theory (DFT), inspecting how easy is to convert CO2 into CO on a set of 18 MXenes even in

adverse conditions of high temperature and low partial pressure of CO22,3, evidencing the easy CO2

conversion through energy barriers ranging from ≈0 to 0.4 eV. This could imply a key role at using the CO

product as a reagent in subsequent processes, such as in Fischer-Tropsch processes.

[1] Persson et al. Adv. Mater. 31 (2019) DOI: 10.1002/adma.201805472. [2] Morales-García et al. J. Mater. Chem. A 6 (2018) 3381-3385. [3] Morales-Salvador et al. Phys. Chem. Chem. Phys. 20 (2018) 17117-17124.


67



How to accurately model IR spectra of silicate grains

Joan Mariñoso Guiu, Antoni Macià, Stefan. T. Bromley

Universitat de Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain

[email protected]

Silicates are ubiquitous both terrestrially and throughout the universe, where they are often present as small particles. Nanosized silicate particles are likely to be particularly important for understanding the formation, processing and properties of cosmic dust grains. Although astronomical infrared (IR) observations and laboratory studies have revealed much about silicate dust, our knowledge of this hugely important class of nanosolids largely rests on top down comparisons with the properties of bulk silicates. Herein, we assess the accuracy of various computational methods for obtaining IR spectra of silicate nanosized dust grains of astronomical interest, directly from the atomistic structure and their atomic motions. First, IR spectra for a selection of small nanosilicate clusters with a range of sizes and chemical compositions are obtained using density functional theory (DFT) within the harmonic oscillator approximation. To check if anharmonicity effects play a significant role in the IR spectra of these nanoclusters, we further obtain IR spectra from finite temperature DFT-based ab initio molecular dynamics (AIMD). Finally, we also study the effect of temperature on the broadening of the obtained IR spectra peaks in a range of larger nanosilicate grains with a range of crystallinities. In this case, less computationally costly classical MD simulations are necessary due to the large number of atoms involved. We present the harmonic broadening that better fit the MD based IR spectra for those large nanosilicate grains IR spectra. Generally, we find that although DFT-based methods are more accurate, surprisingly good IR spectra can also be obtained from classical MD calculations. Overall, our work should provide a new platform for an accurate and detailed understanding of the IR spectra of nanoscale silicates which will thus assist the interpretation of experiment and observation.



68



LIST OF PARTICIPANTS Pere Alemany IQTCUB, University of Barcelona [email protected] Jaume Garcia-Amorós Departament de Química Inorgànica i Orgànica University of Barcelona [email protected] Anton Apostolov Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Konstantin Balashev Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Stanislav Baluschev Max Planck Institute for Polymer Research, Mainz, Germany [email protected] Roger Bujaldón Departament de Química Inorgànica i Orgànica University of Barcelona [email protected]

Zoe Barber Department of Materials Science & Metallurgy, University of Cambridge [email protected] Milen Bogdanov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Ruth E. Cameron Department of Materials Science and Metallurgy, University of Cambridge [email protected]

Chaojian Chen Max Planck Institute for Polymer Research, Mainz, Germany [email protected] Jordi Cirera IQTCUB, University of Barcelona, Spain [email protected] Nikolai Denkov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Giorgio Divitini Department of Materials Science & Metallurgy, University of Cambridge [email protected] Todor Dudev Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Kai Exner Justus-Liebig-University Giessen, Germany [email protected] Marc Figueras IQTCUB, University of Barcelona, [email protected] Albert Figuerola Departament de Química Inorganica i Organica, Universitat de Barcelona [email protected]

Ángel Morales-García IQTCUB, University of Barcelona, [email protected]












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Mihail Georgiev Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Lindsay Greer Department of Materials Science & Metallurgy, University of Cambridge [email protected] Nikolay Grozev Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Joan Mariñoso Guiu University of Barcelona [email protected] Theodor Gurkov Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Ivo Ivanov Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Anela Ivanova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Anabel Jurado IQTCUB, University of Barcelona, [email protected] Irina Karadjova Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

NIkoleta Kircheva Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Spas Kolev School of Chemistry University of Melbourne, Australia [email protected] Ana Koleva Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Iskra Koleva Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Kaloian Koynov Max Planck Institute for Polymer Research, Mainz, Germany [email protected] R Vasant Kumar Department of Materials Science & Metallurgy, University of Cambridge, UK [email protected] Mengxi Lin University of Barcelona [email protected] Rumen Lyapchev Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Valentina Lyubomirova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Galia Madjarova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Lyuben Mihaylov Faculty of Chemistry and Pharmacy, University of Sofia [email protected]













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Kristina Mircheva Faculty of Chemistry and Pharmacy, University of Sofia

[email protected]

Elisaveta Mladenova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Raul Morales IQTCUB University of Barcelona [email protected] Fatmegul Mustan Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Aneli Nedelcheva Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Rositca Nikolova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Petko Petkov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Petar Petrov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Petar Petrov Institute of Polymers Bulgarian Academy of Sciences [email protected] Chris J Pickard University of Cambridge [email protected]

Antoan Rangelov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Boyka Rangelova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Hristo Rasheev Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Konstans Ruseva Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Tsveta Sarafska Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Marin Simeonov

Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Tony Spassov

Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Maya Spassova

Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Silviya Stoykova

Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Ivan Svinyarov

Faculty of Chemistry and Pharmacy, University of Sofia [email protected]














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Christopher V. Synatschke Max-Planck-Institute for Polymer Research, Mainz, Germany [email protected] Alia Tadjer Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Slavka Tcholakova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Rumen Tomov Department of Materials Science and Metallurgy, University of Cambridge, UK [email protected] Stefan Tsakovski Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Vanya Tsakovska Institute of Biophysics and Biomedical Engineering, BAS [email protected] Roumen Tsekov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Martin Tsvetkov Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Zhulieta Valkova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Georgi Vayssilov Faculty of Chemistry and Pharmacy, University of Sofia [email protected]

Zhihong Ye Faculty of chemistry University of Barcelona [email protected], [email protected] Nevena Petkova-Yankova Faculty of Chemistry and Pharmacy, University of Sofia [email protected] Stoyan Yordanov Max Planck Institute for Polymer Research, Mainz, Germany [email protected]

Stanislava Yordanova Faculty of Chemistry and Pharmacy, University of Sofia [email protected]







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