Tuning the light absorption of a molecular vanadium oxide system for enhanced photooxidation performance

A new mechanism for enhancing the visible light absorption of a homogeneous polyoxovanadate system is described. The photoactive pentanuclear {V-5} isopolyoxovanadate cluster is formed in situ by a thermally-induced condensation reaction starting from a tetranuclear {V-4} precursor. Upon irradiation with visible light, {V-5} undergoes a light induced reduction reaction resulting in the formation of a 2-electron reduced {V-10} cluster. Simultaneously, the oxidant methanol is selectively oxidized to formaldehyde. The {V-10} cluster can subsequently be re-oxidized using H2O2 or O-2.