BINDING ABILITY OF N-PARA-AMINO-PHENYLSULFONYL DERIVATIVES OF AMINO-ACIDS - POTENTIOMETRIC AND SPECTROSCOPIC STUDIES OF CU(II) COMPLEXES

N-Para-amino-phenylsulfonyl derivatives of amino acids are very effect ive ligands for Cu(II) ions. Potentiometric and spectroscopic results have shown that Cu(II) ions are able to deprotonate and bind to sulfon amide nitrogen below pH 5 to form stable mono- and bis-{N-, COO-} chel ates. The basicity of sulfonamide nitrogen is lower than peptide amide nitrogen and no distinct anchoring site is necessary to promote the a mide nitrogen deprotonation.