A covalent heterojunction enhances electron transfer and oxygen activation for photocatalytic C(sp3)–C(sp2) cross-dehydrogenative coupling reactions

Abstract

Heterogeneous aerobic photocatalytic oxidation has emerged as a powerful strategy for efficient organic transformations, thus making O₂ activation extremely attractive but challenging due to the spin-forbidden nature of O₂. Herein, we constructed a covalently bonded type-II heterojunction by integrating a porphyrin-based metal-organic framework (PCN-222(Cu)) and the triazine framework (TR-1). Specifically, the strong covalent bond between the two components can extend the visible-light absorption range and facilitate robust interfacial electron transfer, enabling faster separation of photo-induced charge carriers. Consequently, it can effectively activate O₂ through enhanced electron transfer, exhibiting greater catalytic performance with high yields (90%) than the parent compound and the samples without covalent linkage between the two components, extensive adaptability for various substrates, and excellent recyclability in the photocatalytic aerobic oxidative C(sp³)–C(sp²) cross-dehydrogenative coupling reaction. We believe that this is a powerful approach for boosting photocatalytic O₂ activation and offers new insights for manufacturing more composite materials for organic transformations.