Spectrophotometric study of complex formation between iodoquinol (IQ) and Co2+, Mn2+, Cd2+, Pb2+, and Zn2+ in DMF/MeOH binary mixed solvents

The stability constants for complexes of metal ions (M2+) such as Co2+, Mn2+, Cd2+, Pb2+, and Zn2+ with iodoquinol (IQ) at the ionic strength of 0.1 (using NaNO3) have been determined at 25 °C. This study has been done in the binary mixed solvents N,N-dimethyl formamide/Methanol (DMF/MeOH) by a spectrophotometry method. The stoichiometry for M2+/IQ complexes was calculated by applying the “Job” and “molar ratio” methods. A 1:1 complex is generated between each M2+ and the IQ. It was found that the stability constants of the complexes were increased with increasing amount of MeOH in the binary mixtures. The results show that the stability constants decrease in the order Zn2+ > Co2+ > Pb2+ > Mn2+ > Cd2+. The biggest stability constant was found for the Zn2+/IQ system.