cyclic tetranuclear and hexanuclear palladium(ii) complexes and their host-guest chemistry
DESCRIPTION
Cyclic Tetranuclear and Hexanuclear Palladium(II) Complexes and Their Host-guest Chemistry. Judith A. Walmsley,* Shourong Zhu, Antonio Matilla, Tiffanee G. Donowick, Jessica E. Cramp, Jose Manuel Tercero, and Tatyana Dalrymple. Inorg. Chem. 2007 , 46 , 9945-9953. - PowerPoint PPT PresentationTRANSCRIPT
1
Cyclic Tetranuclear and Hexanuclear Palladium(II) Complexes and Their Host-guest Chemistry
Judith A. Walmsley,* Shourong Zhu, Antonio Matilla, Tiffanee G. Donowick, Jessica E. Cramp, Jose Manuel Tercero, and Tatyana Dalrymple
Inorg. Chem. 2007, 46, 9945-9953
2Mirkin, C. A. et al. Angew. Chem. Int. Ed. 2001, 40, 2022-2043
Supramolecular Coordination Chemistry
Hydrogen bonding
Metal-ligand coordination
π-π stacking
Eletrostatic interactions
van der Waals forces
Hydrophobic interactions
Hydrophilic interactions
etc.
3
Selective Formation of Different Geometric Structures by Appropriate Choice of Corner and Bridging Units
Kaiser, A.; Baeuerle, P. Top. Curr. Chem. 2005, 249, 127-201
4
Extraction of Hydrophobic Species into a Water-Soluble Synthetic Receptor
Hooley, R. J.; Van Anda, H. J.; Rebek, J., Jr. J. Am. Chem. Soc. 2007, 129, 13464-13473
5
Molecular Necklace: Quantitative Self-Assembly ofa Cyclic Oligorotaxane from Nine Molecules
Whang, D.; Park, K.-M.; Heo, J.; Ashton, P.; Kim, K. J. Am. Chem. Soc. 1998, 120, 4899-4900
6
Selective Formation of Different Geometric Structures by Appropriate Choice of Corner and Bridging Units
Kaiser, A.; Baeuerle, P. Top. Curr. Chem. 2005, 249, 127-201
7
Structure of Guanine, Guanosine, and Guanosine 5’-monophosphate
(guanosine 5’-monophosphate)
Walmsley, J. A. et al. Inorg. Chim. Acta 2004, 357, 411-420
8
Proposed Coordination Process of Pd(en)2+ with 5’GMP
Walmsley, J. A. et al. Inorg. Chim. Acta 2004, 357, 411-420
9Figure 1. Structure of [Pd(en)(5’GMP)]4
Pd(en)-5’GMP SystemNa2(5’GMP)
8.20
5.95
8.55
6.55
AA’BB’ multipletsinglet
N
N1N7
N
O
NH2
H8
H1'H4'OH OH
H3' H2'
OOPHO
O
O-
PdPd
H2N
NH2
A
B
A'B'
H2N
H2N
10
Figure 2. 1H NMR spectra in D2O at pD 5.4 and 25 °C; (A) [Pd(en)-(5’GMP)]4 (20 mM total Pd(II)); (B) mixture of [Pd(en)(5’GMP)]4 and {-[Pd(en)(5’GMP)]6-DSS} (20 mM DSS and 20 mM total Pd(II)); ‘r’ stands for hexamer host-guest complex, ‘u’ stands for free guest ion.
[Pd(en)(5’GMP)]4 with DSS Guest
Sodium 3-(trimethylsilyl)-1-propanesulfonate (DSS)
-2.76
β-(CH2) 1.19, 1.09 ppm
(Δδ=0.4)
γ-(CH2) -0.91, -1.06 ppm
(Δδ=1.4)
SiH3C
CH3
CH3
(CH2)3 S
O
O
ONa
11
Figure 4. Determination of Pd(en)(5’GMP)/DSS ratio in D2O at pD 5.4 by 1H NMR integrated intensity of the H1’ of host [Pd(en)(5’GMP)]6 and methyl protons of guest DSS; 10 mM total Pd(II) plus variable amounts of DSS.
Determined Pd(en)(5’GMP)/DSS ratio by 1H NMR
slope = 5.9 ± 0.4, 6.0 ± 0.3
12
Figure 3. 31P NMR of 30 mM Pd(en)(5’GMP) in D2O (30 mM total Pd-(II)) with two different concentrations of DSS, pD 5.5; single line at 1.65 ppm is tetramer and two lines at 1.35-1.45 ppm are hexamer with DSS guest.
31P NMR of Pd(en)(5’GMP)/DSS in D2O
tetramer
hexamer
13
Nuclear Overhauser Effect SpectroscopY
• American physicist Albert Overhauser who hypothesized it in the early 1950s. The phenomenon was demonstrated by C. P. Slichter and T. R. Carver in 1953.
• Nuclear Overhauser Effect (NOE) arises throughout radio frequency saturation of one spin, the effect causes the perturbation via dipolar interactions with further nucleus spins.
• NOESY spectra provide information about protons that are 5 Angstroms or less apart in space. The information is through space and not through bond.
14Figure 5. Partial 1H NOESY spectrum of [Pd(en)(5’GMP)]n (19 mM total Pd(II)) with 5 mM DSS in D2O at pD 5.7 and 25 °C.
Partial 1H NOESY Spectrum of [Pd(en)(5’GMP)]n with DSS Guest in D2O
H1’
H8
H8
H1’
H2’, H3’
N
NN
N
O
NH2
H8
H1'H4'OH OH
H3' H2'
OOPHO
O
O-
Pd(en)(en)Pd
methyl group
SiH3C
CH3
CH3
(CH2)3 S
O
O
O-
15
Figure 6. (A) Proposed structure for the hexamer. The 5’GMP units are alternately pointing up and down around the ring. (B) Schematic drawing of [Pd(en)(5’GMP)]6 with DSS guest. The oval represents the Pd(en)-(guanine) and the vertical solid, and wavy lines represent the ribose group. Water molecules may mediate H-bonding between phosphate anions and between phosphate and sulfonate groups.
Proposed Structure for [Pd(en)(5’GMP)]6 Hexamer with DSS Guest
16
pH 4.0 bonding of DSS was first observed
pH 5.0-5.5 reached a maximum
pH 6.0 decreasing
pH 7.7 only a small fraction of the DSS was bonded as host
NH
N
N
O
NH2N
O
H
HHHHOH
OPHO
O
OH
N
N
N
O
NH2N
O
H
HHHHOH
OPHO
O
O-
(en)Pd Pd(en)
N
N
N
O
NH2N
O
H
HHHHOH
OP-O
O
O-
(en)Pd Pd(en)
low pH
pH 5.0-6.0
pH 6.5
Strong pH Dependence of Host-guest Formation
17
Figure 7. 1H NMR spectra of Pd(en)(5’GMP) (20 mM total Pd(II)) and t-butanol in D2O at pD 5.4 and 25 °C. The ‘u’ stands for the resonance from methyl protons of free t-butanol, and ‘r’ stands for methyl protons of guest or H8 and H1’ of hexamer.
1H NMR Spectra of Pd(en)(5’GMP)with t-Butanol Guest in D2O
Pd / t-butanol ratio is 5.9 ± 0.7
18
1H NOESY Spectrum of [Pd(en)(5’GMP)]n with t-Butanol Guest in D2O
N
NN
N
O
NH2
H8
H1'H4'OH OH
H3' H2'
OOPHO
O
O-
Pd(en)(en)Pd
H1’
H8
t-BuOH methylu r
19
Figure 8. 1H NMR resonances of i-butanol as guest in [Pd(en)(5’GMP)]6 in D2O at pD 5.4 and 26 °C; (20 mM total Pd(II) and 10 mM total i-butanol).
1H NMR Spectra of Pd(en)(5’GMP)with iso-butanol Guest in D2O
iso-butanol
heptet
two doubletsequal intensityJ = 7.0 Hz
r
r
r
uu
H8
H1’
u
20
1H NMR Spectrum of Pd(en)(5’GMP)with 2-Propanol Guest in D2O
r uu
r
2-PrOHr
2-PrOHu
H8
H1’
21
1H NMR Spectrum of Pd(en)(5’GMP)with TMS Guest in D2O
CH3
SiH3C CH3
CH3
tetramethylsilane (TMS)
22
Crystal Structure of [Pd(dapol)Cl2]
Figure 10. ORTEP drawing of [Pd(dapo)Cl2] with the atomic numbering scheme; displacement ellipsoids are shown at the 50% level.
Table 4. Selected Bond Lengths (Å) and Angles (deg) for [Pd(dapol)Cl2]
1,3-diamino-2-propanol (dapol)
H2N NH2
OH
23
Figure S12. Packing diagram of [Pd(dapol)Cl2]; Color code: Pd (green), Cl (yellow), C (black), N (blue), O (red), H (white).
Packing Diagram of [Pd(dapol)Cl2]
24
Figure 9. 1H NMR spectra in D2O at 25 °C. (A) 25 mM Pd(dapol)-(5’GMP), pD 5.4 (25 mM total Pd(II)); (B) mixture of (A) and [Pd(dapol)-(5’GMP)]6-2-PrOH (20 mM total Pd(II), 1.5 mM 2-PrOH), pD 5.8. ‘react’ refers to the host-guest complex.
1H NMR Spectra of Pd(dapol)(5’GMP)with 2-Propanol Guest in D2O
1,3-diamino-2-propanol (dapol)
H2N NH2
OH
25
Chemical Shifts of Methyl Protons of Guests in [Pd(diamine)(5’GMP)]n
Table 2. Chemical Shifts of Methyl Protons of Guests in [Pd(diamine)(5’GMP)]na
TSP = Sodium 3-(trimethysilyl)propionate-d4
SiH3C
CH3
CH3
(CH2)3 S
O
O
O-CH3
SiH3C CH3
CH3
O
NaO Si
DD
D D
DSS = Sodium 3-(trimethylsilyl)-1-propanesulfonate TMS = Tetramethylsilane
26
Table 3. K’assoc and Thermodynamic Parameters of [Pd(en)(GMP)]6 Host-Guest Complexes at 26 °C
Association Constants of [Pd(en)(GMP)]6
Host-Guest Complexes
27
Conclusions
1. Upon the introduction of a small organic molecule with hydrophobic interaction sites, the tetramers spontaneously expanded to form a hexamer with one guest molecule strongly incorporated into the central cavity.
2. We feel that the ease with which the tetramer expanded to the hexamer might be related to unfavorable steric interactions of the 5’GMP at the N7-Pd-N7 corners in the tetramer, rendering the expansion in the presence of a templating agent enegetically favorable.
3. The guests can be cationic, anionic, or neutral with a high degree of hydrophobic character. They bind strongly to the host in a 1:1 mole ratio, are in slow chemical exchange with uncomplexed guest molecules, and exhibit very large upfield chemical shifts (2.5-3.0 ppm) in the NMR spectra for the most highly affected protons.