Síntese e caracterização de complexos de cobre (II) com ácidos di-hidroxâmicos

Abstract

Metal complexes play multiple roles in maintaining life, and over the years several studies have been published involving the investigation of complexes aimed at treating various types of diseases. The objective of this work was to contribute to the understanding of the interactions between organic ligands and metal ions, with the goal of identifying new complexes with potential pharmacological applications. The specific objectives were to synthesize copper(II) complexes with acetylacetonate and with di-hydroxamic acids, aiming to clarify how the presence of the hydroxamate group affects complex formation and to compare complexes formed with acetylacetonate and di-hydroxamic acids. In this work, di-hydroxamic acids were chosen for complexation with the Cu(II) ion because they are chelating agents and possess varied functionalities. The hydroxamic acids used in this study were prepared according to methods described in the literature, consisting of the reaction of the carboxylic acid ester with hydroxylamine under basic conditions. The yields obtained for the synthesized ligands were 3.85% for and 18.17%. The products obtained were characterized by infrared spectroscopy, thermogravimetric analysis, melting point, and cyclic voltammetry. The melting point values identified for the ligands were 171–181 °C and 153–155 °C, respectively, and for the synthesized complexes the values obtained were 221–246 °C, 196–198 °C, and 208–215 °C, respectively. The TG curves confirmed the stoichiometry of the coordination compounds in a 1:1 metal:ligand ratio for both ligands, occupying the coordination sphere of Cu(II) through the two chelating coordination sites present in their structures. Experiments involving Copper(II) sebacyl dihydroxamate showed strong interactions between the ligand and Cu(II), and the results demonstrated that the hydroxamate group exhibited stronger interactions than acetylacetonate in the formation of coordination compounds with Cu(II).