Enhancing photocatalysis in conjugated microporous polymers via π-bridge engineering between pyrene and thiazolothiazole

Abstract

Conjugated microporous polymers (CMPs) offer a versatile platform for molecular design that holds significant promise for photocatalysis. The optoelectronic properties of CMPs are intrinsically linked to the characteristics of their constituent molecular units like pyrene, an electron-rich unit, and thiazolo[5,4-d]thiazole (TzTz), a particularly notable electron-deficient unit. Here, we report the design and synthesis of Py-π-TzTz-CMP, a donor–π–acceptor architecture, by engineering an alkyne-based π-bridge into a donor–acceptor architecture, Py-TzTz-CMP. This modification enhances π-electron delocalization across the network, reducing coulombic attraction between electrons and holes, suppressing charge recombination, and improving electron transfer. As a result, Py-π-TzTz-CMP exhibits broader light absorption and superior charge separation and transfer compared to Py-TzTz-CMP. Both CMP photocatalysts demonstrate performance in the aerobic hydroxylation of phenylboronic acids to phenols, with Py-π-TzTz-CMP achieving a reaction rate twice that of Py-TzTz-CMP. Engineering a π-bridge into CMPs provides a new paradigm of steric-electronic trade-offs for enhancing visible light photocatalysis.