Polyoxometalate Complexes of Anatase‐Titanium Dioxide Cores in Water

Abstract

Abstract Polyoxometalate (POM) cluster anions are shown to serve as covalently coordinated ligands for anatase‐TiO 2 nanocrystals, giving isolable assemblies uniquely positioned between molecular macroanions and traditional colloidal nanoparticles. Na + salts of the water‐soluble polyanionic structures are obtained by reacting amorphous TiO 2 with the 1 nm lacunary ion, Na 7 [α‐XW 11 O 39 ] (X=P 5+ ), at 170 °C, after which an average of 55 α‐PW 11 O 39 7− clusters are found as pentadentate ligands for Ti IV ions covalently linked to 6 nm single‐crystal anatase cores. The attached POMs are reversible electron acceptors, the reduction potentials of which shift in a predictable fashion by changing the central heteroatom, X, directly influencing a model catalytic reaction. Just as POM cluster anions control the reactivities of metal centers in molecular complexes, directly coordinated POM ligands with tunable redox potentials now provide new options for rationally controlling the reactions of semiconductor nanocrystals.