Trans ‐A 2 B 2 ‐Type Metalloporphyrin‐Based Donor–Acceptor Covalent Organic Frameworks for Efficient Photocatalytic CO 2 Cycloaddition to Aziridines

Abstract The sunlight‐driven CO 2 cycloaddition to aziridines represents a promising strategy for CO 2 resource utilization, offering a green alternative to conventional thermally driven fixation approach that typically requires high temperatures and/or elevated pressures. Inspired by the exceptional light‐absorption properties of porphyrin derivatives and the enhanced charge separation afforded by a donor‐acceptor (D‐A) configuration, two porphyrin‐based D‐A type covalent organic frameworks (COFs), including metal‐free m ‐DBPA‐COF and metallized m ‐NiDBPA‐COF are synthesized through acid‐catalyzed Schiff base reaction between electron donor (tris(4‐aminophenyl)amine) and electron acceptor ( trans ‐A 2 B 2 ‐type m ‐DBP‐CHO or m ‐NiDBP‐CHO) units. The incorporation of trans ‐A 2 B 2 ‐type metalloporphyrin markedly enhances the transfer and separation of photoinduced charge carriers through ligand‐to‐metal charge transfer (LMCT) and the electron push‐pull characteristic inherent in D‐A configurations. Moreover, the incorporated Ni ions provide Lewis acidic sites that facilitate substrate interactions. Encouragingly, under visible light‐assisted and mild conditions (1 atm CO 2 with no heating required), m ‐NiDBPA‐COF exhibited remarkable photocatalytic performance, achieving a reaction rate of 4.13 mol mol −1 h −1 , which is comparable to that of most thermal catalysts in catalyzing the CO 2 cycloaddition to aziridines. Overall, the study not only provides a guide for the design of porphyrin‐based COF photocatalysts, but also offers a green route to address the CO 2 ‐related resource utilization issues.