Exciton-mediated singlet oxygen generation in a donor–acceptor hydrogen-bonded organic framework for oxidative coupling of benzylamines

Abstract

The selective activation of molecular oxygen remains a central challenge in photocatalytic oxidative coupling of benzylamines, primarily due to inefficient charge separation and uncontrolled radical pathways. In contrast, exciton energy transfer provides a milder and more controllable route by enabling the direct generation of singlet oxygen (¹O₂) without relying on free charge carriers. Herein, we developed a donor–acceptor (D–A) hydrogen-bonded organic framework (HOF), PFC-111, as an intrinsically photoactive catalyst. The hydrogen-bonded linkage between adjacent D–A units facilitates exciton energy transfer, leading to the efficient activation of molecular oxygen under visible light irradiation. As a result, PFC-111 promotes the oxidative coupling of benzylamines under mild conditions with high isolated yield, excellent selectivity, and good recyclability. This work not only establishes PFC-111 as a versatile platform for ¹O₂ organic transformations, but also underscores the great potential of HOFs in sustainable photocatalysis.