A High Nucleus Cu-Incorporated Giant Phosphotungstate with Photocatalytic Oxidation C-H of Toluene.

ABSTRACT

Exploring a novel photocatalyst for catalytic oxidation of toluene is a sustainable strategy for energy conversion in times of an energy crisis. However, designing an effective photocatalyst for the conversion of toluene remains challenging. Herein, a novel organic monophosphonate-modified high nucleus Cu-incorporated polyoxotungstate, K8H33[{Cu0.5(H2O)4}{Cu2(O3PCH2COO)(1,4,9-α-P2W15O56)}]4·Cl·60H2O (1), has been intentionally synthesized by a self-assembly process utilizing conventional aqueous method. It reveals that 1 contains a polyanion of [{Cu0.5(H2O)}4{Cu2(O3PCH2COO)(1,4,9-α-P2W15O56)}]440- composed of four Dawson-type {1,4,9-α-P2W15} subunits, forming an oval-shaped structure and further connecting into a three-dimensional (3D) framework by lateral {Cu(H2O)4}2+. Interestingly, the trivacant {1,4,9-α-P2W15} subunits were observed in the organophosphonate acid-functionalized polyoxometalates for the first time. Notably, 1 exhibits a wonderful performance in catalytic oxidation of the recalcitrant C(sp3)-H bond of toluene to benzoic acid with a conversion as high as 97% under visible light utilizing O2 as an oxidant.