Selenium- and sulfur-containing compounds can act as antioxidants by binding copper. To determine how this copper coordination results in the observed antioxidant activity, biologically relevant Cu + and Cu 2+ complexes with the formulae [Cu(dmit) 3] + (3), [Cu(dmise) 4] + (4a), and [Tpm iPrCu(MISeox)] 2+ (6) (dmise = N,N′-dimethylimidazole selone; dmit = N,N′-dimethylimidazole thione; MISeox = bis(1-methylimidazolyl)diselenide; Tpm iPr = tris(1,3-diisopropylpyrazolyl)methane) were synthesized, characterized, and their structures determined by single-crystal X-ray crystallography. In addition, kinetic studies using UV-vis spectroscopy indicate that dmise reduces Cu 2+ to Cu + three times faster than dmit. Coordination of dmise and MISeox to copper also results in more negative Cu 2+/+ reduction potentials (-373 mV and -503 mV) compared to dmit (-217 mV). These results highlight the different complexation behaviors and reactivities of analogous selone- and thione-containing compounds, traits which likely influence their antioxidant activity.
ASJC Scopus subject areas
- Inorganic Chemistry