Role‐Specialized Division of Labor in CO2 Reduction with Doubly‐Functionalized Iron Porphyrin Atropisomers.

In enzymes, the active site residues function differently to promote chemical reactions. Such a role‐specialized division of labor has been rarely realized by synthetic catalysts. We report herein on catalytic CO2 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 TOFmax of 4.4×105 s−1 in acetonitrile using phenol proton source. Theoretical studies revealed that the two cationic units in the cis‐isomer are more effective than a single cationic unit to improve the CO2 binding, and more importantly, they function differently but cooperatively to promote the C−O bond cleavage: one interacts with the CO2‐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. [ABSTRACT FROM AUTHOR]