Preparation, characterization and bifunctional electrocatalysis of an inorganic–organic complex with a vanadium-substituted polyoxometalate

An inorganic–organic complex with a vanadium-substituted polyoxometalate 1, formulated as [Cu(phen)2]2PVW11O40 was hydrothermally synthesized. Complex 1 crystallizes in the monoclinic P2(1)/c space group with a = 25.9932(12) Å, b = 11.9889(6) Å, c = 23.2672(11) Å, β = 113.6750(10)°, V = 6640.5(6) Å3, R = 0.0312, and Z = 4. Complex 1 is constructed from a Keggin-type anion PVW11O404− coordinated to two [Cu(phen)2]2+ units. One [Cu(phen)2]2+ unit is coordinated to a terminal oxygen and the other [Cu(phen)2]2+ unit is coordinated to a bridging oxygen of the polyoxoanion. Redox activities for both the tungsten and vanadium centers have been observed using cyclic voltammetry performed on 1-bulk modified carbon paste electrode (CPE). It was found that 1 presents good electrocatalytic activities not only for the reduction of IO3−, NO2−, and H2O2 but also the oxidation of l-cysteine. Complex 1 also shows intense luminescent properties arising from ligand-to-copper charge transfer and oxygen-to-vanadium charge transfer at room temperature in the solid state.