Tetrathienoanthracene-functionalized conjugated microporous polymers as an efficient, metal-free visible-light solid organocatalyst for heterogeneous photocatalysis

Abstract

Owing to their advantages of superior inherent porosity, high chemical stability, light weight, and molecularly tunable optoelectronic properties, conjugated microporous polymers (CMPs) have been receiving increasing attention and research interest as promising alternatives to traditional inorganic semiconductors for heterogeneous photocatalysis. Herein, we report the concise synthesis of tetrathienoanthracene-based conjugated microporous polymers (TTA-CMP) via a bottom-up strategy. TTA-CMP was employed as metal-free visible-light solid organocatalyst for three prototypic organic reactions: the dehydrogenative coupling reaction, dehydrogenative-Mannich reaction, and photocatalytic synthesis of benzimidazoles. Indeed, TTA-CMP showed excellent photocatalytic activity (29 examples, 80–98% yield) and outstanding reusability (10–12 times) in these three reactions. The extended π-conjugation in TTA-CMP enhances its visible light absorption, therefore, TTA-CMP displays higher catalytic activity than the corresponding small molecular photocatalyst. This work reveals the bright future of TTA-CMP as an efficient solid organocatalyst for other photocatalytic syntheses.