Elaboration of Covalently Linked Polyoxometalates with Ruthenium and Pyrene Chromophores and Characteriation of Their Photophysical Properties
B. Matt, C. Coudret, C. Viala, D. Jouvenot, F. Loiseau, G. Izzet, A. Proust, Inorg. Chem., 2011, 50, 7761–7768

Keggin and Dawson-type polyoxometalates (POMs) decorated by organometallic [cyclometalated ruthenium(II) polypyridine complex] or organic (pyrene) chromophores were prepared by postfunctionalization of hybrid disilylated POM platforms. The connection is made in a very efficient and modular way via Sonogashira coupling reactions, which provide a rigid linkage between the POM and the photoactive centers. Electronic properties have been inferred from electrochemical and photophysical studies and reflect poor electronic interactions between both partners. The presence of the POM leads to luminescence quenching of the chromophores, which was attributed to an intramolecular electron transfer from the chromophore to the POM. The rate of this process is much faster in the POM-pyrene than in the POM-Ru system. It depends on the driving force dictated by the redox potentials of both partners but also in the case of the POM-Ru system on the presence of the metallacycle, which acts as a molecular insulator and delays the intramolecular electron transfer. In the POM-Ru system, a comparative study of the luminescence quenching showed that the electron transfer is still more important in the covalently bonded hybrids than in systems where the POM and the ruthenium complexes are assembled via electrostatic interactions.

 Versatile host–guest chemistry and networking ability of the cyclic tungstophosphate {P₈W₄₈} : Two further manganese derivatives
Su-Wen Chen, Kamal Boubekeur, Pierre Gouzerh, Anna Proust, J. Mol. Struct., 2011, 994, 104-108.

Two new manganese derivatives of the cyclic polyoxotungstate [H₇P₈W₄₈O₁₈₄]³³⁻ are reported, providing further illustration of its versatile host–guest chemistry. Relatively small changes in the synthetic conditions result in different crystalline compounds 1 and 2 with respectively eight and six manganese(II) ions per {P₈W₄₈} unit. The cyclic cavity of the polyanion accommodates respectively six and four manganese(II) in 1 and 2. In addition, extra tungsten groups are grafted onto the inside of the cavity in 2. The cyclic subunits are differently linked into chains by manganese(II) ions in 1 and 2.

 Hybrid Polyoxometalates : Keggin and Dawson Silyl Derivatives as Versatile Platforms
B. Matt, S. Renaudineau, L.-M. Chamoreau, C. Afonso, G. Izzet, A. Proust, J. Org. Chem. 2011, 76, 3107-3112.

A new series of polyoxometalate-based hybrids has been synthesized. These covalently linked organic-inorganic materials represent valuable elementary building blocks ready for postfunctionalization, using classical organic reactions and couplings. This approach is exemplified by the grafting of an organic chromophore via a Sonogashira coupling.

 Electroactive Benzothiazole Hydrazones and Their [Mo₆O₁₉]^2- Derivatives : Promising Building Blocks for Conducting Molecular Materials S. Gatard, S. Blanchard, B. Schollhorn, P. Gouzerh, A. Proust, K. Boubekeur., Chem. Eur. J., 2010, 16, 8390-8399.

Synthesis of electroactive benzothiazole hydrazones has been achieved and they have been successfully coupled to [Mo₆O₁₉]^2- to give rare examples of diazoalkane-hexamolybdates. The molecular packing arrangements of the hydrazone precursors and the electronic features of the covalent organic-inorganic hybrids showing communication between the organic pi-system and the metal centers make these compounds very promising building blocks for the synthesis of conducting molecular materials.

 Organosilyl/germyl polyoxotungstate hybrids for covalent grafting onto silicon surfaces : towards molecular memories N. Joo, S. Renaudineau, G. Delapierre, G.Bidan, L.-M. Chamoreau, R. Thouvenot, P. Gouzerh, A. Proust, Chem. Eur. J., 2010, 16, 5043-5051.

A hybrid organosilyl/-germyl Keggin polyoxotungstate was covalently grafted to an n-type silicon wafer (see figure) and the electrochemical behavior of the thus modified electrode was investigated.

 Straightforward Synthesis of New Polyoxometalates-based Hybrids Examplified by the Covalent Bonding of a Polypyridyl Ligand V. Duffort, R. Thouvenot, C. Afonso, G. Izzet, A. Proust, Chem. Commun., 2009, 6062–6064.

A new polyoxometalate-based organic/inorganic plateform has been designed for further facile derivatization and covalent attachment of organic linkers. This is examplified by the grafting of a polypyridyl ligand.

 Functionalization of polyoxometalates : towards advanced applications in catalysis and materials science A. Proust, R. Thouvenot, P. Gouzerh, Chem. Commun., 2008, 1837-1852.

Functionalization via covalent grafting of organic functions allows to tune the redox and acid–base properties, and the solubility of polyoxometalates, to enhance their stability and biological activity and to reduce their toxicity, to facilitate their implementation in extended structures and functional devices. We discuss herein the electronic and binding connections, and the various synthesis methodologies. We emphasize on organonitrogen, organosilyl and organophosphonyl derivatives with special attention to synthesis, characterization and potential applications in catalysis and materials science. We also consider the giant molybdenum oxide-based clusters especially the porous capsule-type clusters (Keplerates) which have high relevance to this context.