Visible-light-driven photocatalytic selective oxidation of amines and sulfides over a vanadium metal–organic framework

Abstract

Photocatalytic selective oxidation in organic synthesis has been emerging as an environmentally friendly and energy sustainable approach to produce valuable chemicals, yet it remains a great challenge. In this study, a vanadium(IV) metal–organic framework constructed from triphenyl-based organic linkers, named BIT-66, was first employed as a photocatalyst for the selective oxidation of amines and sulfides in the presence of molecular oxygen or tert-butyl hydroperoxide (TBHP). BIT-66 possesses efficient visible-light absorption and photoinduced charge generation properties, and exhibits an excellent photocatalytic performance for oxidation reactions to produce valuable imines or sulfoxides with a high selectivity under visible light, as well as good reusability. The reactive oxygen species were further investigated via lots of quenching experiments and electron paramagnetic resonance trapping measurements for photocatalytic reactions. It is found that the superoxide radicals, resulting from the photogenerated electron transfer of the excited BIT-66, could be the main active species in the oxidative coupling of amines, while both hydroxyl and peroxyl radicals together play crucial roles in the oxygenation of sulfides using TBHP as the oxidant. This study demonstrates the great potential of photoactive MOFs for organic transformations to produce valuable chemicals.