Effects of Dissolved Water on Li+ Solvation in 1-Ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)amide Ionic Liquid Studied by NMR

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• 作者：Tatsuya Umecky ; Toshiyuki Takamuku ; Tomoya Matsumoto ; Eiji Kawai ; Masaya Takagi ; Toshitaka Funazukuri
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：December 19, 2013
• 年：2013
• 卷：117
• 期：50
• 页码：16219-16226
• 全文大小：329K
• 年卷期：v.117,no.50(December 19, 2013)
• ISSN：1520-5207

文摘

¹H and ⁷Li NMR chemical shifts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide鈥搘ater solutions in the presence and absence of lithium bis(trifluoromethanesulfonyl)amide were determined at 293.2 K over a wide range of water concentrations from 0.0156 to 1.16 mol kg^鈥?. These results revealed the attractive interaction between water molecule and Li⁺ as well as the hydrogen bonding among water molecules. Moreover, self-diffusion coefficients of water, 1-ethyl-3-methylimidazolium cation, Li⁺, and bis(trifluoromethanesulfonyl)amide anion in the ionic liquid solutions at various water contents were determined by ¹H, ⁷Li, and ¹⁹F NMR techniques. It was found that Li⁺ is averagely hydrated by eight water molecules in the ionic liquid solutions. Furthermore, ⁷Li longitudinal relaxation times of Li⁺ in the ionic liquid solutions at 293.2 K were measured with two different magnetic fields and various water contents. The mean one-jump distances of Li⁺ in the ionic liquid solutions were estimated from the correlation times and the self-diffusion coefficients. A comparison between the hydrodynamic radius and the mean one-jump distance of Li⁺ suggested the formation of water channels in the ionic liquid solutions.