Metalloligand Hybrid Polyoxometalates for Efficient Selective Photocatalytic Oxidation of Sulfides to Sulfoxides under Visible-Light Irradiation

The development of novel high-efficiency photocatalysts to solve the bottleneck problems of low efficiency and harsh conditions of organic oxidation reactions is of vital significance. In this paper, a novel hybrid polyoxometalate (POM) crystal, (C2H8N)6[SiW11CdO39][Ru(bpy)2(dcbpy)]·DMF·5.5H2O (RuCd–SiW), was synthesized by combining the metalloligand [Ru(bpy)2(dcbpy)] with the oxidation catalyst POM. The introduction of the metalloligand extended the light absorption range of RuCd–SiW to the visible region, while electrochemical measurements demonstrated its potential as an excellent photocatalyst. Under visible light (λ > 400 nm) irradiation with O2 as the sole oxidant, RuCd–SiW showed highly efficient photocatalytic activity for the selective oxidation of thioanisole to (methylsulfoxide)benzene with a yield of 99.5%, a turnover number of 497.5, and a turnover frequency of 103 h–1. Particularly, the yield of (methylsulfoxide)benzene was still higher than 99% after five rounds of recycling, demonstrating its high stability and recyclability.