Reversed linkage-oriented intermolecular electron-transfer in isomeric covalent organic frameworks for electrochemical CO reduction.

Designing specific electroactive sites and modulating their local microenvironments of covalent organic frameworks (COFs) toward electrochemical CO reduction (ECR) have received increasing attention. However, the underlying impact of the change in intramolecular electron-transfer capability, caused by the tuning in electronic state of active sites, on the redox-mediated catalytic process still remains inadequately understood. In this work, we constructed a metalloporphyrin-based COF as the isomer of the representative COF-367-Co, with an identical chemical composition but a reversed imine-linkage orientation via Schiff-base condensation reaction using [meso-tetrakis(4-formylphenyl)porphyrin]cobalt (CoTFPP) and Benzidine (BD) as the precursors, denoted as CoTFPP-BD-COF, to exclusively investigate the linkage orientation as an individual variable for enhanced electron transmission efficiency toward ECR.