Issue 42, 2019

Influence of the distal guanidine group on the rate and selectivity of O2 reduction by iron porphyrin

Abstract

The O2 reduction reaction (ORR) catalysed by iron porphyrins with covalently attached pendant guanidine groups is reported. The results show a clear enhancement in the rate and selectivity for the 4e/4H+ ORR. In situ resonance Raman investigations show that the rate determining step (rds) is O2 binding to ferrous porphyrins in contrast to the case of mononuclear iron porphyrins and heme/Cu analogues where the O–O bond cleavage of a heme peroxide is the rds. The selectivity is further enhanced when an axial imidazole ligand is introduced. Thus, the combination of the axial imidazole ligand and pendant guanidine ligand, analogous to the active site of peroxidases, is determined to be very effective in enabling a facile and selective 4e/4H+ ORR.

Graphical abstract: Influence of the distal guanidine group on the rate and selectivity of O2 reduction by iron porphyrin

Supplementary files

Article information

Article type
Edge Article
Submitted
04 Jun 2019
Accepted
28 Aug 2019
First published
29 Aug 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 9692-9698

Influence of the distal guanidine group on the rate and selectivity of O2 reduction by iron porphyrin

A. Ghatak, S. Bhakta, S. Bhunia and A. Dey, Chem. Sci., 2019, 10, 9692 DOI: 10.1039/C9SC02711D

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