Spectroscopic, structure and antimicrobial activity of new Y(III) and Zr(IV) ciprofloxacin

The preparation and characterization of the new solid complexes {[}Y(CIP)(2)(H(2)O)(2)]Cl(3)center dot 10H(2)O and {[}ZrO(CIP)(2)Cl]Cl center dot 15H(2)O formed in the reaction of ciprofloxacin (CIP) with YCl(3) and ZrOCl(2)center dot 8H(2)O in ethanol and methanol, respectively, at room temperature were reported. The isolated complexes have been characterized with elemental analysis, IR spectroscopy, conductance measurements. UV-vis and (1)H NMR spectroscopic methods and thermal analyses. The results support the formation of the complexes and indicate that ciprofloxacin reacts as a bidentate ligand bound to the metal ion through the pyridone oxygen and one carboxylato oxygen. The activation energies. E{*}; entropies, Delta S{*}; enthalpies, Delta H{*}; Gibbs free energies, Delta G{*}, of the thermal decomposition reactions have been derived from thermogravimetric (TGA) and differential thermogravimetric (DTG) curves, using Coats-Redfern and Horowitz-Metzeger methods. The proposed structure of the two complexes was detected by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand as well as their metal complexes was also evaluated for their antibacterial activity against several bacterial species, such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) and antifungal screening was studied against two species (Penicillium (P. rotatum) and Trichoderma (T. sp.)). This study showed that the metal complexes are more antibacterial as compared to free ligand and no antifungal activity observed for ligand and their complexes. (C) 2010 Elsevier B.V. All rights reserved.