Synthesis and characterization of new copper (II) coordination compounds with unsymmetrical N,O-donor ligands: Contributions for the galactose oxidase active site

The reactions of four new unsymmetrical N,O-donor ligands, {H2BBPETEN=[N-(2-hydroxybenzyl)-N,N'-bis(2 methylpyridyl)-N'-(hydroxyethyl) ethylenodiamine], H3BPETEN=[N,N'-bis(2-hydroxybenzyl)-N-(2-methylpyridyl)-N'-(hydroxyethyl) ethylenodiamine], HTPETEN=[N,N,N'-tris(2-methylpyridyl)-N'-(hydroxyethyl) ethylenodiamine] and H3BIMETEN=[N,N'-(2-liydroxybenzyl)-N-(1-methylimidazol-2-il-methyl)-N'-(hydroxyethyl)ethylenodiamine]}, with Cu(ll) salts afforded the following mononuclear compounds: [Cu-II(HBBPETEN)]ClO4, [Cu-II(H2BPETEN)]ClO4, [Cu-II(HTPETEN)](PF6)(2) and [Cu-II(H2BIMETEN)]ClO4. All were characterized by EPR, electronic spectroscopy and electrochemistry. The four copper (II) compounds showed interesting electrochemistry properties. All presented an anodic wave that can be attributed to the Cu (1) Oxide formation at the electrode surface, or to a Cu-0 sediment at the same surface or yet, to Cu(l) --> CU(II) Oxidation process with coupled chemistry reaction, due to their irreversibility. Two of the complexes arc described as interesting synthetic models for the active site of the metalloenzyme galactose oxidase.