Metal Complexes of Enrofloxacin Part I: Preparation, Spectroscopic, Thermal Analyses Studies and Antimicrobial Evaluation

Abstract

The interaction of titanium (IV), yttrium (III), zirconium (IV), palladium (II) and cerium (IV) with deproto- nated enrofloxacin leads to the formation of the neutral or cationic mononuclear complexes. The isolated solid complexes have been characterized with physicochemical and spectroscopic techniques and thermogravimeteric analyses. The spectro- scopic data indicate that the enrofloxacin ligand is on the deprotonated mode acting as bidentate ligand coordinated to the metal ions through the ketone oxygen and a carboxylato oxygen and the metal ions completed the coordination number with water molecules. The thermal decomposition mechanisms proposed for enrofloxacin and their metal complexes were discussed. The activation energies, E * , enthalpies, ∆H * , entropies, ∆S * and Gibbs free energies, ∆G * , of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves, using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The antimicrobial activity has been evaluated against six different microorganisms.