Role‐Specialized Division of Labor in CO₂Reduction with Doubly‐Functionalized Iron Porphyrin Atropisomers

Abstract

In enzymes, the active site residues function differently to promote chemical reactions. Such a rolespecialized division of labor has been rarely realized by synthetic catalysts. We report herein on catalytic CO 2 reduction with Fe porphyrins decorated with two cationic N,N,N-trimethylbenzylamine groups in cis-or trans-arrangement. The cis-isomer outperforms the trans-isomer and reaches a TOF max of 4.4 × 10 5 s À 1 in acetonitrile using phenol proton source. Theoretical studies revealed that the two cationic units in the cisisomer are more effective than a single cationic unit to improve the CO 2 binding, and more importantly, they function differently but cooperatively to promote the CÀ O bond cleavage: one interacts with the CO 2 -adduct, while the other one interacts with the phenol molecule through electrostatic interactions. This work therefore presents a significant example of synthetic catalysts, which boost chemical reactions using a role-specialized strategy for substrate activation.