Metal complexes of the fourth generation quinolone antimicrobial drug gatifloxacin: Synthesis, structure and biological evaluation

Three metal complexes of the fourth generation quinolone antimicrobial agent gatifloxacin (GFLX) with Y(ΙΙΙ), Zr(ΙV) and U(VΙ) have been prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, gatifloxacin acts as a bidentate deprotonated ligand bound to the metal through the ketone oxygen and a carboxylato oxygen. The complexes are six-coordinated with distorted octahedral geometry. The kinetic parameters for gatifloxacin and the three prepared complexes have been evaluated from TGA curves by using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The calculated bond length and force constant, F(UO), for the UO2 bond in uranyl complex are 1.7522 Å and 639.46 N m−1.The antimicrobial activity of the complexes has been tested against microorganisms, three bacterial species, such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) and two fungi species, penicillium (P. rotatum) and trichoderma (T. sp.), showing that they exhibit higher activity than free ligand.