Mixed-ligand complexes of copper(II) with salicylhydroxamic acid as primary ligand and amino acids, peptides, DNA units, or amines as secondary ligands

The formation equilibria of the mixed-ligand complexes of copper(II) with salicylhydroxamic acid (H(2)SHAM) and amino acids, peptides or DNA units have been investigated by the potentiometric technique. The ternary complexes are formed in a stepwise mechanism, whereby H2SHAM first binds to Cu(II) and then ligates to the secondary ligand. The formation constants of the formed complexes were determined at 25 degrees C and mu = 0.1 MNaNO3. The results indicate that the apical coordination of the ionized amide group of the peptide and the ionized alcoholato group of the amino acids serine and threonine is not possible. The ternary complexes involving Cu(II), H(2)SHAM and aromatic amines such as 2,2'-bipyridyl or 1,10-phenanthroline were synthesized and characterized.