Direct synthesis of triphenylamine-based ordered mesoporous polymers for metal-free photocatalytic aerobic oxidation

Abstract

Visible-light active, heterogeneous, and metal-free photocatalysts represent a more sustainable and environmentally friendly alternative to conventional metal-based photocatalysts. Highly ordered mesoporous polymers (OMPs) with tunable periodic structures, ordered and uniform mesopores, and excellent stability can become a promising platform for heterogeneous photocatalysis of organic transformations. Here we report the preparation of triphenylamine (TPA) functionalized ordered mesoporous polymers (TPA-MPs) through a facile and cost-effective process. The new three-dimensional connected networks possess periodic porosity, excellent stability and good photoelectric response characteristics. Among them, TPA-MP-1 was selected as the optimized heterogeneous photocatalyst for visible-light driven cross coupling of glycine derivatives with indoles and synthesis of 2-substituted benzothiazoles using oxygen in air as a green oxidant. In addition, the TPA-MP-1 catalyst can be easily recovered with good retention of photocatalytic activity and reused at least five times, demonstrating its good recyclability. This work highlights the opportunity in constructing a new generation of metal-free, heterogeneous photocatalysts for organic transformations.