Transformation
of CO2 into valuable chemicals and especially
fuels is deemed as a promising approach to reduce our dependence on
fossil fuels and to alleviate climate change. Carbazole-based porous
polymers bearing rhenium-metalated polypyridine functionalities were
constructed via simple oxidative coupling reaction. These porous polymers
are employed as heterogeneous supports for immobilization of catalytically
active rhenium complexes and furthermore provide high CO2 adsorption capabilities and light absorption abilities, i.e., photosensitizing
properties. Consequently, such rhenium-metalated microporous polycarbazole
networks show high efficiencies for CO2 photoreduction
upon visible-light irradiation, with a CO evolution rate up to 623
μmol g–1 h–1 and selectivity
of 97.8%. The microporous solid photocatalyst shows enhanced stability
and photocatalytic performance compared to the molecular catalysts
during long-term use.
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.
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