Micellar effects on the complex formation reaction of copper (II) with ciprofloxacin

Abstract

Complex formation between Cu (II) and ciprofloxacin in aqueous micellar media has been reported. Conventional spectroscopic and <i style="mso-bidi-font-style:normal">p</i>H-metric methods have been adopted to investigate the micellar effects. Both cationic (cetyltrimethylammonium bromide, CTAB and cetylpyridinium chloride, CPC) and anionic (sodiumdodecylsulphate, SDS) surfactants have been used in the investigation. Results indicate considerable micellar effects with SDS, while the effects of CTAB and CPC are marginal. Deprotonation of ciprofloxacin hydrochloride is hindered in aqueous SDS medium, but the complex formation between Cu (II) and ciprofloxacin is considerably enhanced. The Cu (II) ciprofloxacin complex in SDS medium absorbs at 657 nm. The absorbance – [SDS] profile exhibits double maxima, one below cmc and the other almost at the cmc of SDS. The results are explained in terms of pseudo-phase model whereby it is assumed that the complex formation reaction predominantly occurs on the negatively charged SDS micellar surface compared to the bulk aqueous phase. From the rate-[SDS] profile, binding constant of ciprofloxacin-SDS is found to be 20.