Comparative Studies of Structures and Peroxidase-like Activities of Copper(II) and Iron(III) Complexes with an EDTA-Based Phenylene-Macrocycle and Its Acyclic Analogue
dataset
posted on 2019-12-18, 19:06 authored by Melissa Beltran-Torres, Rocío Sugich-Miranda, Hisila Santacruz-Ortega, Lorena Machi, Motomichi Inoue, Enrique F. Velázquez-Contreras, Yedith Soberanes, Herbert Höpfl, Refugio Pérez-González, Rosa Elena Navarro, Alex J. Salazar-Medina, Rogerio R. Sotelo MundoWith the objective of studying the conformational and
macrocyclic effects of selected metal chelates on their peroxidase
activities, Cu<sup>2+</sup> and Fe<sup>3+</sup> complexes were synthesized
with a macrocyclic derivative of ethylenediaminetetraacetic acid and <i>o</i>-phenylenediamine (abbreviated as edtaodH<sub>2</sub>)
and its new open-chain analogue (edtabzH<sub>2</sub>). The Fe<sup>3+</sup> complex of edtaodH<sub>2</sub> has a peroxidase-like activity,
whereas the complex of edtabzH<sub>2</sub> does not. The X-ray study
of the former shows the formation of a dimeric molecule {[Fe(edtaod)]<sub>2</sub>O} in which each metal with an octahedral coordination is
overposed over the macrocyclic cavity, as a result of rigid macrocyclic
frame, to form an Fe–O–Fe bridge; the exposure of the
central metal to the environment facilitates the capture of oxygen
to drive the biomimetic activity. The peroxidase-inactive Fe<sup>3+</sup> complex consists of a mononuclear complex ion [Fe(edtabz)(H<sub>2</sub>O)]<sup>+</sup>, the metal ion of which is suited in a distorted
pentagonal bipyramid to be protected from environmental oxygen. The
copper(II) complexes, which have mononuclear structures with high
thermodynamic stability compared with the iron(III) complexes, show
no peroxidase activity. The steric effects play a fundamental role
in the biomimetic activity.
