Synthesis and reactivity of Copper complexes for Oxygen reduction

Abstract

Oxygen reduction catalyzed by copper-containing enzymes and their synthetic analogs is one of the most fundamental processes and has gained much attention due to its application in fuel cells. In this study, two copper complexes containing dipicolylaminebased ligands were successfully prepared, and their reactivity towards oxygen reduction was examined. The CuII complexes were synthesized from reaction of DPA or L (DPA = 2,2'-dipicolylamine; L = 9-[(2,2'-dipicolylamino)methyl]anthracene) with Cu(ClO₄)₂ in CH₂Cl₂ /CH₃OH (1:1 v/v). The CuII products were then characterized by mass spectrometry, elemental analysis and UV-vis spectroscopy. Monitored by UV-vis, reaction of CuII complexes and ascorbic acid under nitrogen atmosphere resulted in the formation of CuI species. It was also shown that the presence of anthracene moiety in the Cu complexes has a significant influence on CuII reduction and stability of the CuI species. In addition, when [CuIL]+ was exposed to oxygen atmosphere, the CuII species was slowly regenerated. The result suggested that [CuIL]+ was capable of mediating oxygen reduction.