Complexation equilibria of ciprofloxacin with proton and metal ions in aqueous-organic mixutres

Abstract

The proton-ligand stability constants (log K 1 H , log K 2 H ) of ciprofloxacin (CIP) and its metal-ligand stability constants (log K 1 ) in aqueous, acetonitrile-water, alcohol-water, DMSO-water and 1,4-dioxan-water (25 : 75 and 50 : 50% v/v) mixtures have been determined potentiometrically at 25 ± 0.1 °C and 0.1 mol dm -3 (NaCl) ionic strength. Ciprofloxacin formed 1: 1 (M: L) complexes with VO, Cu, Zn, Ni, Mn and Co. In general, the values of log K 1 follow Irving-Williams stability order in each solvent system.