Synthesis, Characterization and Biological Profile of Cationic Cobalt Complexes with First-Generation Quinolones.

The interaction of cobalt(II) with first-generation quinolones oxolinic acid (Hoxo), flumequine (Hflmq), pipemidic acid (Hppa) and cinoxacin (Hcx) in the presence of the N,N'-donor heterocyclic ligands 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen) afforded a series of novel cobalt complexes, namely [Co(bipy)(2)(oxo)](PF(6))(2)·H(2)O (1), [Co(phen)(2)(oxo)](PF(6))(2)·0.5CH(3)OH·0.5H(2)O (2), [Co(bipy)(2)(flmq)](PF(6))(2)·0.5CH(3)OH·0.5H(2)O (3), [Co(bipy)(2)(ppa)](PF(6))(2)·CH(3)OH·0.5H(2)O (4), [Co(phen)(2)(cx)](PF(6))(2)·CH(3)OH·0.5H(2)O (5), and [Co(phen)(2)(flmq)](PF(6))·0.5CH(3)OH·H(2)O (6). The characterization of the complexes involved physicochemical techniques, various spectroscopies and single-crystal X-ray crystallography. The affinity of complexes to calf-thymus (CT) DNA was monitored with various techniques, suggesting intercalation in-between the DNA-nucleobases as the most probable interaction mode, which may be combined with electrostatic interactions as a result of the cationic nature of the complexes. The affinity of the complexes for bovine and human serum albumin proteins was monitored, and the determined corresponding albumin-binding constants revealed a tight and reversible interaction.