Hydrazone-based covalent organic frameworks for efficient photocatalytic redox reactions

Abstract

Covalent organic frameworks (COFs) have emerged as an exciting class of organic porous materials with tremendous potential in heterogeneous catalysis. Thermal/chemical stabilities, adjustable porosities, and tunable functionalities with the flexible installation of active sites are promising features in COF-based photocatalysis. This work focuses on synthesis and analysis of two hydrazone-linked COFs, namely MOH-Tf1₁Tf2₁ and MOH-Tf1₁Tf2₂, and their photocatalytic application in the visible-light-induced synthesis of benzothiazole derivatives. Significantly, MOH-Tf1₁Tf2₁ exhibits remarkable substrate tolerance and high catalytic activity, together with excellent stability and recyclability in the catalytic process. To our delight, MOH-Tf1₁Tf2₁ also exhibits outstanding yield in large-scale synthesis of benzothiazole. The enhanced catalytic performance of COF-based systems could be attributed to efficient charge separation and migration of charge carriers of these extended π-conjugation networks. The present study also provides valuable information for addressing the structure–function correlations in COF photocatalyst systems and highlights promising opportunities in developing COF platforms with a wide range of photocatalytic applications.