Cationic Polycarbazole Networks as Visible-Light Heterogeneous Photocatalysts for Oxidative Organic Transformations

Photoredox catalysis has aroused great interest from chemists, as it offers a powerful tool for organic synthesis. Cationic polycarbazole networks (CPOP-28 and CPOP-29) were prepared via simple oxidative coupling reaction and applied as heterogeneous photocatalysts for a wide range of oxidative organic transformations, including oxidation of sulfides, hydroxylation of arylboronic acids, and crossdehydrogenative coupling reactions, in the presence of visible light and air. Remarkably, photocatalytic activities are enhanced by ingenious introduction of trifluoromethyl groups to the polymeric network CPOP-29. The effects of the trifluoromethyl group on photocatalytic activities were elucidated in terms of photophysical and electrochemical properties. The appealing photocatalytic performance of the trifluoromethylated polymer is ascribed to superior light-absorption ability, longer fluorescence lifetime, and stronger oxidative capability. In addition, the photocatalysts showed good recyclability and could be reused after a simple separation workup.