Hybrid Organic–Inorganic Porphyrin–Polyoxometalate Complexes

Two Anderson‐type polyoxomolybdates [FeMo6O18{(OCH2)3CNHCO(4‐C5H4N)}2]3– and [MnMo6O18{(OCH2)3CNHCO(4‐C5H4N)}2]3– and two Lindqvist‐type polyoxovanadates [V6O13{(OCH2)3CCH2OC(O)(4‐C5H4N)}2]2– and [V6O13{(OCH2)3CNHCO(4‐C5H4N)}2]2– were functionalized with pendant pyridyl groups. The electrochemical analysis revealed reversible redox processes at the heteroatom of the Anderson‐type compounds and at the vanadium atoms in the Lindqvist series. Axial coordination of the polyoxometalate‐grafted pyridyl groups to the metal ion in [Ru(CO)TPP] (TPP = tetraphenylporphyrin) and [ZnTPP] yielded polyoxometalate–porphyrin assemblies in solution. Evidence for electronic communication between the polyoxometalate and the porphyrin was established by fluorescence spectroscopy. Cyclic voltammetry showed the influence of the porphyrin on the redox process of the polyoxometalate and also nucleophilic attack at the porphyrin skeleton by the pendant pyridyl groups. Implications for the construction of supramolecular functional devices based on these components are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)