Porous aromatic frameworks with precisely controllable conjugation lengths for visible light-driven photocatalytic selective C-H activation reactions

Abstract

Organic visible light-active porous polymers have been established as a novel promising class of heterogeneous photocatalysts for a variety of important photoredox reactions. To date, given the usually fully conjugated nature of most polymer-based photocatalysts, precise control of the energy band structure and thereby their redox potentials in photocatalytic reactions while retaining highly active surface area is a huge challenge. Here, we design a series of porous aromatic frameworks (PAFs) with precise control of the conjugation length within the polymer architecture as efficient metal-free photocatalysts. The polymers exhibit a high intrinsic surface areas of up to 1070 m2/g as well as tunable optical and redox properties that allow applications in C-H activation reactions driven selectively either by the photogenerated electron or hole species. Furthermore, as an attractive example for high-value chemical conversions, the formation of dantrolene, an active pharmaceutical ingredient, was successfully catalyzed by the PAFs in the simple one-pot cascade synthesis.