Structural Change of 1-Butyl-3-methylimidazolium Tetrafluoroborate + Water Mixtures Studied by Infrared Vibrational Spectroscopy

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• 作者：Yoonnam Jeon ; Jaeho Sung ; Doseok Kim ; Chungwon Seo ; Hyeonsik Cheong ; Yukio Ouchi ; Ryosuke Ozawa ; Hiro-o Hamaguchi
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：January 24, 2008
• 年：2008
• 卷：112
• 期：3
• 页码：923 - 928
• 全文大小：198K
• 年卷期：v.112,no.3(January 24, 2008)
• ISSN：1520-5207

文摘

Mixtures of ionic liquid (IL, 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF₄]) and water withvarying concentrations were studied by attenuated total reflection infrared absorption and Raman spectroscopy.Changes in the peak intensities and peak positions of CH_x (x = 1, 2, 3) vibration modes of the cation of theIL and OH vibration modes of the water molecules were investigated. Peaks from normal-mode stretchvibrations of CH bonds belonging to the imidazolium ring of the cation did not change their positions, whilethose from the terminal methyl group of the butyl chain blueshifted by ~10 cm^-1 with the addition of water.On the other hand, change in the spectral shape in the OH stretch vibration region shows hydrogen-bondingnetwork of water molecules breaking down rapidly as the IL is added. Trends in the change of the peakpositions and the peak intensities suggested qualitative change of the intermolecular structure in the [BMIM][BF₄] + H₂O mixture at 32 ± 2 and 45 ± 2 mol/L of water concentration.