Donor-acceptor type two-dimensional porphyrin-based covalent organic framework for visible-light-driven heterogeneous photocatalysis

Abstract

• New metal-free acceptor-donor type COFs were synthesized. • As-synthesized COFs exhibited excellent photocatalytic properties. • The simulation of energy levels reveals the mechanism of electron transfer. • The COFs have excellent recyclability. Two-dimensional covalent organic frameworks (2D-COFs) with permanent porosity, structural controllability, and excellent stability, are receiving ongoing attention in metal-free heterogeneous photocatalysis of organic conversions. In order to construct high optical performance COFs for selective organic transformation, herein, 2D porphyrin-based donor-acceptor (D-A) type COFs were prepared by adjusting the morphology and structure. The as-synthesized COFs facilitate charge transfer and separation of photogenerated electron-hole pairs, efficaciously producing superoxide radical anions as mediates for selective oxidation of sulfides (97% conversion and 99% of selectivity) and reductive dehalogenation of 2-bromoacetophenone (up to 99% conversion and 82% of yield). The COFs have excellent stability and recyclability, demonstrating that the 2D D-A type COFs are attractive as heterogeneous photocatalyst for visible light driven organics transformation.