The Photoactive Hydrazone-Linked Covalent Organic Frameworks for Photocyclization Approach to Phenanthridine Derivatives

Covalent organic frameworks (COFs) with precise designable structures are becoming popular semiconductor materials for photocatalytic applications. In this study, a hydrazone-linked COFs ( TFPT-ODH ) material was constructed from the reversible polycondensation of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine with oxalohydrazide. Thanks to the bottom-up strategy, the as-prepared TFPT-ODH exhibited satisfactory crystallinity, high thermal and chemical stability. The benefit of the combined effects of narrow band gap and efficient separation of photogenerated carriers, the photofunctional TFPT-ODH further demonstrated outstanding photocatalytic activity, stability, and recyclability in the photocatalytic cyclization reactions of 2-isocyanodiaryl compounds with phenylhydrazine. The photocatalytic mechanism for the photocyclization approach to phenylphenanthridines was proposed based on experimental data and spectrum techniques. Our work also demonstrates application in developing COFs-based photocatalysts for the photocatalytic cyclization of bioactive PAHs derivatives. Graphical abstract