Halogen Regulation in Vinylene-Linked Covalent Organic Frameworks for Efficient Photocatalytic C–H Thiolation of Quinone Derivatives

Vinylene-linked covalent organic frameworks (COFs) are considered promising heterogeneous photocatalyst candidates for organic synthesis because of their robust and conjugated frameworks. For the first time, a series of vinylene-linked COFs decorated by halogen atoms (F, Cl, and Br) were synthesized and further utilized as photocatalysts for C–H activation reactions. The corresponding optoelectronic properties could be precisely regulated via the modulation of halogen functionalities in the nanopore channel of COFs. It is worth noting that the unique structures and optoelectronic properties make these COFs effective photocatalysts for C–H activation reactions in organic synthesis. All of the COFs exhibited extraordinary catalytic performance and reusability in C–H functionalization based on halogen functionalities. Especially, the highest yield was achieved in the photocatalytic C–H thiolation of 1,4-naphthoquinones with Br-COF photocatalyst because of the suitable conduction band position. This work may provide a new scaffold to rationally design vinylene-linked COFs as efficient photocatalysts in organic synthesis.