Synthesis, characterization and antimicrobial investigation of some moxifloxacin metal complexes

The new complexes of moxifloxacin (MOX), with Ti(IV), Y(III), Pd(II) and Ce(IV) have been synthesized. These complexes were then characterized by melting point, magnetic studies and spectroscopic techniques involving infrared spectra (IR), UV-Vis, (1)H NMR. C, H, N and halogen elemental analysis and thermal behavior of complexes also investigated. The results suggested that the molar ratio for all complexes is M: MOX = 1:2 where moxifloxacin acts as a bidentate via one of the oxygen atoms of the carboxylate group and through the ring carbonyl group and the complexes have the following formula {[}Ti(MOX)(2)](SO(4))(2)center dot 7H(2)O, {[}Y(MOX)(2)Cl(2)]Cl center dot 12H(2)O, {[}Pd(MOX)(2)(H(2)O)(2)]Cl(2)center dot 6H(2)O and {[}Ce(MOX)(2)KSO(4))(2)center dot 2H(2)O. The activation energies, E{*}, enthalpies, Delta H{*}, entropies, Delta S{*} and Gibbs free energies, Delta G{*}, of the thermal decomposition reactions have been derived from thermogravimetric (TGA) and differential thermogravimetric (DrTG) curves, using Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and three Gram-negative bacteria and compared with the reference drug moxifloxacin. The antibacterial activity of Ti(IV) complex is significant for E. coli K32 and highly significant for S. aureus K1, B. subtilis K22. Br. otitidis K76, P. aeruginosa SW1 and K. oxytoca K42 compared with free moxifloxacin. (C) 2011 Elsevier B.V. All rights reserved.