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Institut für Anorganische und Angewandte Chemie

Institut für Anorganische und Angewandte Chemie. Dieter Rehder NMR 2 – Polyoxometalates and Biological Applications PICB Winter School Shanghai 5th-10th March 2007. Nuclei of interest in the context of characterising polyoxometalates and modelling ion transport.

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Institut für Anorganische und Angewandte Chemie

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  1. Institut für Anorganische und Angewandte Chemie Dieter Rehder NMR 2 – Polyoxometalates and Biological Applications PICB Winter School Shanghai 5th-10th March 2007

  2. Nuclei of interest in the context of characterising polyoxometalates and modelling ion transport

  3. Applications of 51V, 95Mo and 183W NMR: Characterising polyoxometalates

  4. Species differentiation by chemical shifts 51V NMR of an aq. solution of 5 mM vanadate, pH 5.7 Vb Va Vc

  5. H4V14PO425- (Capped a-Keggin) -506 (capping V) 1 1 1 -560, -582 (other V) P

  6. H6V15O423- (Capped a-Keggin) -531 (2 capping VO5) -584, -597 (VO6) V -507 C. L. Hill, Chem. Commun. 1993, 426

  7. A host-guest system based on a polyoxovanadate, stabilised by a large cation [Bu4N]4[MeCNV12O32] d(51V) = -590 (4V) -598 (4V) -606 (4V) W.V. Day et al. JACS111 (1989) 5959

  8. From Keggin to Dawson 1 1 3 3 2 2 Remove 1, 2 and 3, and fuse

  9. 183W NMR spectra of Dawson-type polyoxotungstates [P2MoW17O62]n- P P [P2W18O62]n- R. Contant, Inorg. Chem. 1991, 30, 1695

  10. 183W NMR spectra of polyoxotungstates [Mn+As4W40O140](28-n)- M *Line which is strongly cation-dependent O. Howarth, in: Polyoxometalates 1994, 167

  11. [HMo7O24]5- [MoO4]2- Variable temperature 95Mo NMR spectra (molybdate at pH 6) [MoO4]2- [HMo7O24]5- 49 °C 39 °C 30 °C 19 °C 4 °C A.G. Wedd, Aust. J. Chem. 1984, 37, 1825

  12. Applications of 7Li and 23Na NMR: Modeling ion transport by porous polyoxomolybdates in cooperation with Prof. Achim Müller (Bielefeld) and Dr. Erhard Haupt (Hamburg)

  13. Why Li+ ? • Lithium salts are used in the treatment of • Bipolar disorder (manic depression) • high blood pressure (hypertension) • lacking blood supply (ischaemic injury) • Viral infections How does Li+ act? • Competition with Na+ and K+ (disturbance of the Na+/K+ balance) • Inhibition of Mg2+ activated enzymes in signal transduction (e.g. inositol-6-phosphatase) • Modulation of the activity of Mg2+ dependent enzymes in metabolic pathways (e.g. pyruvate kinase)

  14. 7Li NMR: - nuclear spin: 3/2 - quadrupole moment: –4.5 fm2 - natural abundance: 92.85% - receptivity (1H = 1): 0.6

  15. 7Li NMR of erythrocytes (red blood cells) in the presence of Li+ outside Li+ inside 0 5 [Li(H2O)4]+

  16. Paramagnetic shift reagent Dy3+, 4f9: 5 unpaired electrons, magnetic moment: 10.65 BM

  17. Cell membrane with cation ion channel

  18. Ion channel - details blue: Protein Na+, K+ O2- (of carboxy-lates or carbonyl)

  19. Porous Polyoxomolybdates – Models for cellular cation transport [Me2H2N]44Li28{MoVI(MoVI5O21)(H2O)6}12{MoV2O4(SO4)}30•200H2O Diameter ca. 3 nm; 20 pores (0.42 nm  *) and channels, one cavity (containing water cluster) *Effective pore radius: ca. 0.6 Å [Mo132O372(H2O)72(SO4)30]72-

  20. MoO6 polyhedra Sulfate Pore, accomodatingLi+ Detail from the outer surface (viewed from the interior) 2 Mo9O9 rings are linked together by a central {Mo2} unit

  21. Detail from the outer surface, showing one of the pores in a lateral view, with a Na+ attached to 3sulfates and 3 water molecules (towards cavity of the capsule) [Mo132O372(H2O)72(SO4)30]72-

  22. [Li(solv)4]+ Cross-section of cluster capsule [Li(dmso)x]+ 7Li NMR in DMSO, concentration dependence Li+{Mox} [Li(H2O)4]+ Chem. Commun. 2005, 3912-3914

  23. Cross peaks 7Li-2D-EXSY NMR Mixing time: 1.5 ms [Li(dmso)x]+ Li+{Mox} Li+

  24. blocks {Mo9O9} pore 7Li-2D-EXSY NMR in the presence of guanidinium cations: [Li(dmso)x]+ Li+{Mox}

  25. Li+{Mox} + guanidinium guanidinium Li+{Mox} [Li(dmso)x]+ 7Li NMR in the presence of increasing amounts of Dy3+-triphosphate no Dy3+ added External reference

  26. [Li(dmso)n]+ [Na(dmso)n]+ Li+{Mo} Na+{Mo} 7Li NMR 23Na NMR x 10  Increasing c(Na+)  Chem. Asian J. 2006, 76

  27. No (substantial) exchange with Cs+ Essentially the same behaviour is observed for K+, Rb+ and Ca2+ Ionic radii* (coord. number 6) / Å _______________________________ Li+ Na+ K+ Rb+Cs+Ca2+ 0.78 0.98 1.33 1.49 1.641.06 *from close packing ion volumes

  28. Replacement of Li+ by K+ [Li(dmso)n]+ [Li+{Mox}] Increasing c(K+)

  29. Ca2+ completely removes Li+ from internal capsule sites (excess) Ca2+ added no Ca2+

  30. [Li(dmso)n]+ Li+{Mo} 7Li NMR in the presence of Cs+: no substantial exchange Increasing c(Cs+)

  31. Chem. Commun. 2005, 3912 Influence of water [Li(dmso/H2O)4]+ [Li(H2O)x]+{Mox} Equilibrium accelerated by water c(H2O) 2.5 M 0.26 M 0.16 M dry 0.26 M (ca. 0.4%)

  32. Summarising provisional assignments of lithium sites

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