Visible-Light-Mediated Selective Fluorine Incorporation by Anthraquinone-Based Covalent Organic Framework as Recyclable Photocatalyst

Abstract

Covalent organic frameworks (COFs) serve as an excellent foundation for heterogeneous photocatalysis. Herein, we synthesized an anthraquinone-based COF (TpAQ) on a gram scale via a mechanochemical grinding pathway. This COF was employed as a visible-light-harvesting photocatalyst for selective fluorination of benzylic C─H bonds and perfluoroalkylation of arenes. The carbonyl core in the anthraquinone linker facilitated benzylic fluorination through a hydrogen atom transfer (HAT) pathway. Control experiments and photophysical analysis were conducted to gain deeper insight into the reaction mechanism. The recyclability up to the fifth cycle without significant loss of yield (>90%) highlighted the robustness of the catalyst. This reaction strategy was also executed on a gram scale to validate the scalability of the protocol.