Affiliation:
1. Centro de Química Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla (BUAP), Ciudad Universitaria, Col. Jardines de San Manuel, Puebla, Pue. 72570, Mexico
2. Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla (BUAP), Ciudad Universitaria, Col. Jardines de San Manuel, Puebla, Pue. 72570, Mexico
Abstract
The synthesis and characterization of a novel hexacoordinated compound as a product of the reaction between chlorodimethylesterprotoprphyrin–Fe(III) 1 and 2–methylpiridine (2–CH3Py) was performed. The [bis(o–methylpyridino)(dimethylesterprotoporphyrinato)Fe(III)] chloride 2 is a compound of the family of the pinch–porphyrins, a model of peroxidase enzymes. We analyzed 2 using UV-Vis, 1H NMR, and EPR spectroscopies, as well as kinetic quantifications of its peroxidase activity and computational analysis, to evaluate the presence of the pinch-ligand coordinated to 1 in a series of pinch-ironprotoporphyrin complexes, as previously reported. Our investigation revealed that the oxidant activity of Compound I derived from peroxidase activity determination of 1 and 2, respectively, is better controlled when a heterohydrocarbonated chain is attached to the pyridyl groups that coordinate axially to 1; an effect evidenced by a decrease of the activation energy value associated with Compound 0 formation during the reaction performed by pinch–porphyrin, with the picdien axial ligand and hydrogen peroxide. When correlating the contribution of [Formula: see text]3/2 in the quantum mixed-spin state (qms), [Formula: see text]3/2, [Formula: see text]5/2, of iron(III)-based complexes with their peroxidase activity, we found that when the qms [Formula: see text]3/2, [Formula: see text]5/2, of iron(III) had 80% character [Formula: see text]3/2, the peroxide activity increased significantly. This could be a fundamental trait that could affect the peroxidase activity owing to the distortion of the iron geometry associated with its coordination number when o−methylpyridine is used as an axial ligand.
Funder
CONACyT network of national laboratories
Publisher
World Scientific Pub Co Pte Ltd