Carbazole-triazine based donor-acceptor porous organic frameworks for efficient visible-light photocatalytic aerobic oxidation reactions

We report the synthesis of a series of carbazole-triazine based donor-acceptor (D-A) POFs and their photocatalytic activities for aerobic oxidation reactions. The simultaneous introduction of a carbazole-based electron donor and a triazine-based electron acceptor in D-A POFs stabilizes the charge transfer state and enables an efficient triplet-triplet energy transfer to generate O-1(2). Meanwhile, systematic variation of the D-A distance results in the tunable photoredox properties and consequently the efficiency for generation of reactive oxygen species (ROSs). Upon visible light excitation, all three D-A POFs exhibit excellent capability to promote three aerobic oxidations: sulfide oxidation, oxidative amine coupling, and Mannich reactions. This systematic study validates the design principle of D-A POFs as high-performance photo-oxidation catalysts with wide substrate scope and excellent stability and recyclability.