Equilibrium studies of binary and ternary complexes of oxytetracycline and amino acid or DNA units

Abstract

The acid-dissociation constants of oxytetracycline (OTC) and the formation constants of the copper(II) complexes were determined att=25°C and μ=0.1 mol dm−3 (NaNO3) in dioxane-water mixtures. The mixed-ligand complexes of copper(II) with OTC as primary ligand and amino acids or DNA constituents as secondary ligands were investigated in 50% v/v dioxane-water mixture. The formation constants of the complexes formed in solutions and their concentration distributions as a function ofpH were evaluated. The relative stabilities of the ternary and corresponding binary complexes were also studied.