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

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