Síntese e caracterização de complexos heterolépticos de Fe e Mn a partir de ligantes piridínicos como modelos biomiméticos da enzima metano monooxigenase

Abstract

Bioinorganic chemistry plays a central role in understanding the behavior of various metal ions in a variety of biological systems. A class of enzymes that act in redox reactions using molecular oxygen as an oxidizing agent are known as oxygenases. Methane monooxygenase, a binuclear iron enzyme, is capable of oxidizing methane to methanol, which generates great interest due to its ability to labile C-H bonds in hydrocarbons. Using the structure found in the active site of the enzyme as inspiration, mononuclear complexes of FeII and MnII were proposed from nitrogenous ligands seeking to reproduce the catalytic properties of Methane monooxygenase. As a strategy for the preparation of these compounds, we used a bidentate and a tridentate ligand, resulting in an N5-donor system, leaving the sixth posítion free for interaction with oxidizing agents (O2, H2O2) aiming at the formation of the possible active species for the oxidation of hydrocarbons. These synthetic complexes of rigid structure present catalytic activity against the oxidation of benzyl alcohol substrate in the conversion range of 40%. Through these studies, two mononuclear complexes of FeII and MnII with the 2,2’-bipyridine ligand and the N,N’-bis (pyridinylmethyl)hydrazine ligand were proposed, synthesized and characterized, which presents a benzyl alcohol conversion of 46 % in 6 hours demonstrating that the rigid structure of the ligands has little influence on their conversion rate.