O-2(-) SCAVENGER PROPERTIES OF COPPER(II) COMPLEXES WITH DIAMINO-DIAMIDE-TYPE LIGANDS

Copper(II) complexes with diamino-diamido-type ligands were tested as catalysts of O-2(-) dismutation. ESR spectra of these systems showed that, in consequence of the O-2(-) interaction, all the bis complexes of formula [Cu(L)(2)H--2] (where L = L-valylamide, L-phenylalanylamide, L-prolylamide) transformed into [Cu(L)H--1(OH)(2)] species. They also showed the highest scavenger as well as catalytic activity. The complex species formed after the interaction continued to show scavenger activity also. Stronger copper(II) complexes hardly interacted and showed scarce scavenger properties. In the series of [Cu(L')H--2] complex species (where L' = (S,S)N,N'-bis(phenylalanyl)1,2-ethanediamine and -1,3-propanediamine and (S,S)N,N'-bis(prolyl)-1,2-ethanediamine) the attempt to correlate catalytic activity with structural features revealed that a longer methylene chain could become a critical factor.