Synthesis, spectral and thermal studies of the sodium salts of some Ru(III) complexes with quinolone antibiotics

Solubilisation by salt formation is an effective method to increase the solubility of slightly soluble drugs, applied especially for the development of liquid formulations for parenteral administration. In the present study, this strategy is applied for new Ru(III) complexes with quinolone antibiotics, valuable for biological application such as anticancer activity. The parent compounds, formulated as RuCl (3) (HL) (2) (DMSO) (m) (H (2) O) (n) (HL: pipemidic acid, norfloxacin, ciprofloxacin, ofloxacin, levofloxacin, enrofloxacin, enoxacin), were transformed in their corresponding soluble sodium salts with general formula Na (2) RuCl (3) (L) (2) (DMSO) (m) (EtOH) (n) (H (2) O) (p) . The sodium salts have been characterised by elemental analysis and some spectrometric methods (IR, UV-Vis, mass spectra). The thermal behaviour of these newly compounds was studied by simultaneous TG/DTG/DTA analysis, and it was evidenced a higher thermal stability compared to that of the parent compounds. The thermal transformations occur in two or three steps and comprise solvent (solvation or coordination) elimination as well as oxidative degradation of quinolone derivatives. A mixture of ruthenium and sodium chloride was identified as final residue.