@misc{oai:repo.qst.go.jp:00068904,
 author = {Ｍａｎｄａ, Ｓｕｓｈｍａ and 中西, 郁夫 and 川島, 知憲 and 大久保, 敬 and 金澤, 秀子 and 小澤, 俊彦 and 福住, 俊一 and 伊古田, 暢夫 and 安西, 和紀 and Ｍａｎｄａ Ｓｕｓｈｍａ and 中西 郁夫 and 川島 知憲 and 小澤 俊彦 and 伊古田 暢夫 and 安西 和紀},
 month = {Mar},
 note = {Recently we have reported that 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine- N-oxyl (3-carbamoyl-PROXYL, CP), one of cyclic nitroxyl radicals used as a spin probe for in vivo electron spin resonance (ESR) measurements, can act as an electron donor to scavenge a reactive oxygen radical.1  Thus, the one-electron oxidation potentials of cyclic nitroxyl raicals are of considerable importance to evaluate their radical-scavenging activity.  In this study, the solvent effect on the redox behavior of CP and 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl (TEMPOL) has been investigated by the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) in acetonitrile, methanol, or aqueous phosphate buffer.
The different voltammetric profiles were observed for these two nitroxyl radicals in various solvents of different nature, demonstrating that the higher the solvent polarity becomes, the more negatively shifted the one-electron oxidation potential.  Furthermore, the viscosity of solvents was also found to limit the oxidation of nitroxyl radicals by controlling diffusion of species at the electrode surface.  Since the one-electron oxidation potentials of nitroxyl radicals are closely related to their radical-scavenging activity, the detailed electrochemical data obtained in this study provides valuable information to develop novel cyclic nitroxyl radicals with stronger radical-scavenging activity.  Furthermore, it is also possible to evaluate the extent of scavenging as the unequal diffusion current in different solvents reflects the different concentration of scavenger oxidized that consequently reveal the extent of scavenging in corresponding solvent by the scavenger.
In conclusion, solvent polarity and solvent viscosity play an important role in the one-electron oxidation of nitroxyl radicals and it may be possible to augment the radical-scavenging efficiency by choosing a proper solvent., 日本化学会第87春季年会},
 title = {ニトロキシルラジカルの酸化還元挙動に対する溶媒効果},
 year = {2007}
}