Donor-acceptor engineering of a triplet-exciton-optimized MOF photocatalyst for efficient singlet oxygen-mediated oxidation

Abstract

The exploration of photocatalysts (PCs) for efficient singlet oxygen (¹O₂)-based photocatalytic oxidation is critical and challenging. Herein, a new series of donor-acceptor metal-organic frameworks (D-A MOFs) are constructed through the engineering of the D-A system, and investigated as PCs for the ¹O₂ oxidation reaction. By regulating the intersystem crossing and reversed intersystem crossing features of the D-A system, D-A MOFs could reveal highly tunable triplet-exciton generation. Via the synergy of the enhanced electron transfer properties and the effective energy transfer to ground-state O₂, the optimized D-A MOF (<b>C1</b>) could reveal remarkable activity toward ¹O₂ generation under appropriate irradiation, which is fully proven by the highly efficient oxidation and detoxification of mustard simulant 2-chloroethyl ethyl sulfide into 2-chloroethyl ethyl sulfoxide (conversion and selectivity >99% within 15 min). Moreover, the application of <b>C1</b> for the photocatalytic oxidation of dihydroartemisinic acid to artemisinin results in the highest selectivity and yield (selectivity 88% and conversion >99% at 25°C) among all reported homo- or heterogeneous PCs.