A thermodynamic study of complexation of ciprofloxacin and lomefloxacin with aluminium ion.

Gibbs energy, enthalpy and entropy for the reactions of ciprofloxacin and lomefloxacin with aluminium ion were determined. No significant differences were observed for Gibbs energy values for these fluorquinolones while significant differences were found for enthalpy and entropy. The highly positive values observed for the entropy give evidence for a strong cation-ligand interaction and point out the role of hydration in the complex formation. As the value of the entropy for the reaction with ciprofloxacin is higher than that observed for lomefloxacin one concludes that the former ligand interacts more strongly with the metal ion than the latter.