Synthesis and Characterization of N3s2 Donors Macrocyclic Copper(ii) Complexes. Catechol Oxidase and Phenoxazinone Synthase Biomimetic Catalytic Activity.

Abstract

A new series of hexa-, and five-coordinated copper(II) complexes, having the molecular formulae of [CuLX]X H 2 O, 1, 2, 3 (X = Cl¯, Br¯, NO 3¯) and [CuL]X 2 nH 2 O, 4, 5 (X= AcO¯ and ClO 4¯) respectively and L is pentadentate pyridine based ligand have been synthesized. Structural characterization of these newly synthesized compounds was achieved by several physicochemical methods including elemental and thermal analysis (TGA and DTG), electrical molar conductance, magnetic moment measurements and spectral investigations such as IR, UV-Vis and ESR. The spectral and magnetic measurements in addition to the electrolytic conductance results demonstrated the octahedral and square-pyramidal stereochemistries for the hexa, and five coordinated copper(II) chelates respectively. Catechol oxidase and phenoxazinone synthase biomimetic catalytic activity of the inspected copper(II) chelates was studied and the results obtained indicated that, the catalytic reactivity is markedly depends on the structural properties of these newly synthesized copper(II) complexes. …………………………………………………………………………………………………….... Introduction:-Functional models of the metalloenzymes that activate molecular oxygen possess great potential as catalyst for specific oxidation reactions and as guides for the development of efficient small molecule catalysts [1]. Since, the oxidation of organic substrates with molecular oxygen under mild conditions is of great interest for industrial [2] and synthetic processes both from an economical and environmental [3] point of view, most of the focus of ongoing biomimetic and bioinspired synthetic approaches is on reproducing some structural and/or functional feature of the title enzymes. The synthesis and reactivity studies of transition metal complexes, as functional model compounds for metalloenzymes with oxidase activity, are of particular interest for the development of bioinspired catalysts for oxidation reactions.The potential role played by copper ions in the active sites of a large number of metalloproteins has stimulated efforts to design and characterize copper complexes as models for providing better understanding of biological systems and for assisting in the development of new homogeneous catalysts for selective oxidation. Particularly, the