A photo- and redox actives mesoporous 3D covalent organic framework enables highly efficient metal-free photoredox catalysis

Abstract

Visible-light photoredox catalysis has been emerged as prominent methodology for efficient chemical synthesis. However, the relying use of soluble noble-metal photoredox catalysts suffer from long-term supply, inefficient separation, and could pos serious threats to the environment. Development of recyclable metal-free photoredox catalyst is thus highly significance. Herein, suitable molecular chromophore and redox units are condensed into photo- and redox active mesoporous 3D COF (3D TAPPy-TFPA) that enable highly efficient photoredox catalysis. The 3D COF displayed high crystallinity, mesoporous channel, and excellent structural stability. Optical and electrochemical studies revealed the excellent light harvesting, redox activity and effective generation of reactive radical species to induce photoredox catalysis. As proof-of-concept, 3D TAPPy-TFPA efficiently catalyzed the visible-light induced photoredox thiol-ene cross coupling and thiol radical mediated acylation of amines with activities surpassing most of the reported soluble photoredox catalysts. Beside recoverable, 3D TAPPy-TFPA showcased the previously inaccessible diacylation of amine into di-amide with high selectivity. This report shows robust design of outstanding and low-cost photoredox catalyst and paves the development of functional 3D COFs.