Microscopic Aspects in Dicationic Ionic Liquids through the Low-Frequency Spectra by Femtosecond Raman-Induced Kerr Effect Spectroscopy
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- Hideaki Shirota
- Department of Nanomaterial Science, Graduate School of Advanced Integration Science & Department of Chemistry, Faculty of Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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- Tateki Ishida
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
書誌事項
- 公開日
- 2011-08-30
- 資源種別
- journal article
- DOI
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- 10.1021/jp206266e
- 公開者
- American Chemical Society (ACS)
この論文をさがす
説明
The interionic vibrations in imidazolium-based dicationic ionic liquids (ILs) containing the bis(trifluoromethylsulfonyl)amide ([NTf(2)](-)) counteranion were investigated using femtosecond optical-heterodyne-detected Raman-induced Kerr effect spectroscopy. The microscopic nature of the dicationic ILs ([C(n)(MIm)(2)][NTf(2)](2), where n = 6, 10, and 12; MIm = N-methylimidazolium) was compared with that of the corresponding monocationic ILs ([C(n)MIm][NTf(2)], where n = 3, 5, and 6) used as reference samples. Low-frequency Kerr spectra within the frequency range 0-200 cm(-1) of the ILs revealed that (i) the spectral profile of the dicationic ILs as well as that of the corresponding monocationic ILs is bimodal; (ii) the difference in the spectral shapes of the dicationic and monocationic ILs is greater for [C(6)(MIm)(2)][NTf(2)](2) and [C(3)MIm][NTf(2)] than for the ILs with longer alkylene linker/alkyl groups, namely [C(10)(MIm)(2)][NTf(2)](2) and [C(5)MIm][NTf(2)], and [C(12)(MIm)(2)][NTf(2)](2) and [C(6)MIm][NTf(2)]; (iii) the small difference between the dicationic and monocationic ILs is confirmed by the relative intensity of the low-frequency component (ca. 17 cm(-1)) to the high-frequency component (ca. 70 cm(-1)); and (iv) the spectral profiles of the three dicationic ILs are not very different, but the line-shape of the low-frequency Kerr spectrum of 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)amide ([C(3)MIm][NTf(2)]) is significantly different from those of the other two monocationic ILs whose cations have a longer alkyl group. The distinguished line-shape of the low-frequency Kerr spectrum of [C(3)MIm][NTf(2)] from the other ILs can be accounted for by the homogeneous nature in the microstructure of the IL, but the other ILs indicate microsegregation structures due to the longer nonpolar alkylene linker or alkyl group in the cations.
収録刊行物
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- The Journal of Physical Chemistry B
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The Journal of Physical Chemistry B 115 (37), 10860-10870, 2011-08-30
American Chemical Society (ACS)
