Synthesis, spectral and oxidase studies of a new diamide copper(II) complex with pendant benzimidazolyl groups
作者:Sunil K. Upadhyay、Sarita Tehlan、Pavan Mathur
DOI:10.1016/j.saa.2006.03.002
日期:2007.2
A new benzimidazole-based diamide ligand-N,N '-bis(alanine-2-benzimidazolyl) hexanediamide (ABHA) has been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(ABHA)X-2](nH2O)-H-center dot, where X is an exogenous anionic ligand (X = Cl-, NO3-). Low temperature EPR spectra has been obtained that shows g(parallel to) > g(perpendicular to) > 2.0024, indicating a tetragonal geometry in the solution state. The complexes display a quasi-reversible redox wave due to the Cu(II)/Cu(I) reduction process. E-1/2 values shift anodically as NO3- < Cl-, indicating that the bound NO3 stabilizes the Cu(II) ion while the bonded Cl- destabilizes it. The complex [Cu(ABHA)Cl-2] has been found to oxidize dopamine to dopachrome or aminochrome, both in a methanolic and a reverse-miceller system. The oxidation of dopamine to aminochrome is reminiscent of the functioning of Prostglandin H-synthetase in brain cells which requires dopamine as a cofactor for catalytic activity. (c) 2006 Elsevier B.V.. All rights reserved.