Research progress on visible-light-induced C–H functionalization reactions catalyzed by covalent organic frameworks

<p indent="0mm">Covalent organic frameworks (covalent organic frameworks, COFs) are an emerging class of heterogeneous photocatalysts characterized by excellent crystallinity, high surface area, and outstanding stability. Compared to traditional homogeneous and heterogeneous photocatalysts, COFs exhibit tunable photocatalytic performance and reusability, making them increasingly applicable in the visible-light-induced organic small molecule conversion. The visible-light-induced functionalization of C–H bonds, which does not require pre-functionalized precursors, has become an important method for organic transformations. As heterogeneous photocatalysts, COFs not only eliminate the use of expensive transition metals but also reduce environmental pollution caused by their emissions, providing a more economical, efficient, and green catalytic pathway for visible-light-mediated C–H bond functionalization. This review briefly introduces the intrinsic factors affecting the catalytic performance of COFs from three aspects: monomers, linkages, and synthesis methods. Additionally, in conjunction with our works, it delves into the types, mechanisms, and developmental trajectories of visible-light-mediated C(sp³)–H and C(sp²)–H functionalization reactions. Finally, this review summarizes the advantages and disadvantages of COFs in visible-light-promoted C–H bond functionalization reactions and discusses potential future directions in this field.