A copper(II) complex of an asymmetrically N-functionalized derivative of 1,4,7-triazacyclononane: synthesis, crystal structure and SOD activity

A copper(II) complex chlorido-{1-carboxylic acid ethyl ester-4, 7-bis[ 1-(carboxylic acid ethyl ester) benzimidazole-2-yl-methyl]-1,4, 7-triazacyclononane} copper(II) hexafluorophosphate ethanol solvate ([CuClL]center dot PF6 center dot EtOH) was synthesized and crystallographically characterized {where L = 1-carboxylic acid ethyl ester-4,7-bis[1-(carboxylic acid ethyl ester) benzimidazole-2-yl-methyl]-1,4,7-triazacyclononane}. X-ray structure analysis shows that the copper(II) adopts a distorted square pyramidal coordination geometry. The activity of dismutation of superoxide (O-2(-)) of the complex in riboflavin-methionine-nitroblue tetrazolium was studied. The result shows that the complex possesses a high superoxide dismutase (SOD) activity in comparison to some reported SOD mimics. Its redox behavior was studied by cyclic voltammetry with the aim of elucidating the reason that the complex reduces superoxide radicals.