Mono and Diphosph(on)ate Containing POMs

Mono-&-Di

Polyoxometalates have some properties that make them attractive for applications in medicine. The nanometer size, charge-density, high stability and high solubility of polyoxoanions seem important features for them being potentially active medicinal agents. The anti-HIV activities of a number of heteropolyanions have been investigated and many of them show inhibition properties, but toxicity remains a problem. Furthermore the mechanism of action is not well understood. Most compounds studied so far have compact structures of the Keggin or Wells-Dawson type.

A family of diphosph(on)ate complexes of polyoxometalates exhibits a uniquely open structure with the heterogroups in external positions and the anti HIV-1 properties of these compounds are very interesting. Furthermore the mechanism of action of these compounds was elaborated. The results show that the compounds are potent inhibitors of HIV-1 by interaction with the reverse transcriptase enzyme, but unfortunately problems with selectivity were observed.

An advantage of heteropolyanions with external heterogroups is that derivatization of the heterogroup after formation of the polyoxoanion is possible in principle. This pathway might allow to fine-tune specific properties (e.g. lipophilicity, charge-density) of the polyoxoanion resulting in a species that is more specific as a medicinal agent (drug-design).

We reported the first example of a complex of molybdate with diphosphate isolated from aqueous solution and structurally characterized. The hexamolybdopyrophosphate, [(O3POPO3)Mo6O18(H2O)4]4- has been characterized by 31P-NMR, IR, elemental analysis and single-crystal X-ray diffraction. The polyanion consists of a six-membered ring of MoO6 octahedra, which alternate in sharing edges and corners and can be viewed as the first structurally-characterized intermediate in the molybdate-catalyzed hydrolysis of pyrophosphate.

We have also synthesized a compact polyoxometalate, [{(P2O7)Mo15O45}2]8-, with two internal diphosphate groups. The structure of this novel anion has been elucidated in solution by 31P-NMR spectroscopy and in the solid state by single-crystal X-ray diffraction. The 30-molybdobispyrophosphate contains two eclipsed diphosphate ions with linear P-O-P bonds (180.0(10)°). The dimeric polyanion can be viewed as a fused dimer of two lacunary [(P2O7)Mo15O48] moieties leading to a cigar-shaped structure with four belts and two caps.


Selected Publications

  • Chiral Strandberg-type Molybdates [(RPO3)2Mo5O15]2- as Molecular Gelators: Self-Assembled Fibrillar Nano-Structures with Enhanced Optical Activity
    Carraro, M.; Sartorel, A.; Scorrano, G.; Maccato, C.; Dickman, M. H.; Kortz, U.; Bonchio, M. Angew. Chem. Int. Ed. 2008, 47, 7275-7279. [Read Online]
  • Cation Dependent Formation of Hybrid Organic-Inorganic Frameworks Based on the Strandberg-Type Polyanion [(O2CCH2PO3)2Mo5O15]6- and Cu2+ Ions
    Chubarova, E. V.; Klöck, C.; Dickman, M. H.; Kortz, U. J. Clust. Sci., 2007, 18, 697-710. [Read Online]
  • Heteropolymolybdates of Phosphate, Phosphonate and Phosphite Functionalized by Glycine
    Kortz, U.; Vaissermann, J.; Thouvenot, R.; Gouzerh, P. Inorg. Chem. 2003, 42, 1135-1139. [Read Online]
  • Polyoxomolybdates Functionalized with Phosphonocarboxylates
    Kortz, U.; Marquer, C.; Thouvenot, R.; Nierlich, M. Inorg. Chem. 2003, 42, 1158-1162. [Read Online]
  • Complete List of Publications