Copper(II) complexes of amino acids and peptides containing chelating bis(imidazolyl) residues

Copper(II) complexes of amino acids and peptides containing the chelating bis(imidazolyl) residues have been reviewed. The results reveal that bis(imidazolyl) analogues of these biomolecules are very effective ligands for metal binding. The nitrogen donor atoms of the chelating agent are the major metal binding sites under acidic conditions. In the presence of terminal amino group the multidentate character of the ligands results in the formation of various polynuclear complexes including the ligand and the imidazole bridged dimeric species. The most intriguing feature of the coordination chemistry of these ligands is that the deprotonation of the coordinated imidazole-N(1)H groups results in the appearance of a new chelating site in the molecules. It leads to the formation of stable trinuclear complexes via negatively charged imidazolato bridges.