Integrating Two Photochromics into One Three-Dimensional Covalent Organic Framework for Synergistically Enhancing Multiple Photocatalytic Oxidations

While photocatalytic oxidations are a category of important reactions in wide chemical synthesis, the fabrication of effective photocatalysts for broad oxidation reactions is still of a great challenge. Herein, by rationally integrating two photochromics, porphyrin and triphenylamine, a three-dimensional photoactive covalent organic framework (COF) is successfully constructed for photocatalytic oxidations. Characterization studies not only show the formation of a crystalline and three-dimensional porous framework, but also reveal its effective photochemical semiconductor properties derived from the porphyrin and triphenylamine moieties. Electron paramagnetic resonance measurements indicate that the COF is an effective photocatalyst for the generation of both singlet oxygen (¹O₂) and superoxide radical anions (⋅O₂⁻). Synergistically enhanced efficiency in all photocatalytic reactions of photocatalytic aerobic oxidation of alkylbenzenes and silanes as well as thioanisoles, and cross-dehydrogenative coupling reaction of N-phenyltetrahydroisoquinoline and indole is confirmed by both experimental and theoretical studies, demonstrating its promising potential for broad photocatalytic oxidation reactions.