Synthesis, characterization and interaction with DNA of mononuclear metal complexes with oxolinic acid

Seven new neutral mononuclear metal complexes of VO2+, Mn2+, Fe3+, CO2+, Ni2+, Zn2+ and Cd2+ with the quinolone antibacterial agent oxolinic acid (=Hoxo) have been prepared and characterized with physicochemical and spectroscopic techniques. In all the complexes, oxolinic acid acts as a bidentate deprotonated ligand bound to the metal through the pyridone oxygen and one carboxylate oxygen. The metals in all the complexes are six-coordinate with slightly distorted octahedral geometry. The lowest energy model structures of the complexes Fe(oxo)(3), VO(oxo)(2)(H2O) and Mn(oxo)(2)(H2O)(2) have been determined with molecular modeling calculations. The ability of all the complexes to bind to calf-thymus DNA has been investigated with diverse spectroscopic techniques. (c) 2007 Elsevier Ltd. All rights reserved.