Photochemically Stable Amide-Linked Covalent Organic Framework for Efficient Dual Photoredox and Copper Catalysis

Covalent organic frameworks (COFs) have shown promise in photocatalysis, but currently, there are limited synthetic strategies for the simultaneous integration of efficient photosensitizers and catalytic metal sites into COFs for dual metallaphotoredox catalysis. Herein, we report the synthesis of an amide-linked COF (Am-COF) via oxidative linkage transformation of an imine-linked COF (Im-COF), significantly enhancing photochemical stability and catalytic activity in alkene arylation reactions under visible-light irradiation. Im-COF was oxidized with KHSO5 to form Am-COF and then coordinated with Cu centers via bipyridine moieties to form Am-COF-Cu. The addition of phenanthrolines to Am-COF-Cu formed both Cu photosensitizers and catalysts to mediate dual photoredox and Cu catalysis. With enhanced stability, Am-COF-Cu efficiently catalyzed arylazidation, arylbromination, and arylthiocynation reactions of 27 alkene substrates and was used in five consecutive reaction runs without the loss of catalytic activity. Mechanistic studies revealed a dual photoredox and Cu catalysis process.