Engineering single–atom active sites anchored covalent organic frameworks for efficient metallaphotoredox C[sbnd]N cross–coupling reactions

Abstract

Photoredox catalysis has become an indispensable solution for the synthesis of small organic molecules. However, the precise construction of single-atomic active sites not only determines the catalytic performance, but also avails the understanding of structure–activity relationship. Herein, we develop a facile approach to immobilize single-atom Ni sites anchored porous covalent organic framework (COF) by use of 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,6-diformylpyridine (Ni SAS/TD-COF). Ni SAS/TD-COF catalyst achieves excellent catalytic performance in visible-light-driven catalytic carbon–nitrogen cross-coupling reaction between aryl bromides and amines under mild conditions. The reaction provides amine products in excellent yields (71%–97%) with a wide range of substrates, including aryl and heteroaryl bromides with electron-deficient, electron-rich and neutral groups. Notably, Ni SAS/TD-COF could be recovered from the reaction mixture, corresponding to the negligible loss of photoredox performance after several cycles. This work provides a promising opportunity upon rational design of single-atomic active sites on COFs and the fundamental insight of photoredox mechanism for sustainable organic transformation.