Binding ability of N-Para-amino-phenylsulfonyl derivatives of amino acids. Potentiometric and spectroscopic studies of Cu(II) complexes

Abstract N-Para-amino-phenylsulfonyl derivatives of amino acids are very effective ligands for Cu(II) ions. Potentiometric and spectroscopic results have shown that Cu(II) ions are able to deprotonate and bind to sulfonamide nitrogen below pH 5 to form stable mono- and bis-[N − , COO − ] chelates. The basicity of sulfonamide nitrogen is lower than peptide amide nitrogen and no distinct anchoring site is necessary to promote the amide nitrogen deprotonation.