Visible-Light-Driven C–S Coupling Reaction Using Covalent Organic Framework Films

A visible-light-driven C–S cross-coupling reaction using covalent organic frameworks (COFs) as heterogeneous photocatalysts is reported. Three β-keto-enamine-linked COFs, TpAzo, TpDPP, and TpBDMe 2, were synthesized and systematically evaluated. Among them, TpAzo exhibited superior photocatalytic activity due to its high surface area (1725 m 2 g –1 ), low band gap (1.78 eV), and efficient charge separation. To enhance the reusability and accessibility, a thin-film morphology of TpAzo COF was developed, which facilitated catalyst recovery and sustained performance over multiple cycles. The optimized protocol enabled the arylation of thiols with a wide range of aryl halides, including iodides, bromides, chlorides, tosylates, and mesylates, delivering the corresponding thioethers in good to excellent yields (55–94%) under ambient conditions. This study highlights the potential of COF-based photocatalysts for sustainable C–S bond formation and broadens their application in organic synthesis