Conformations of 1-Butyl-3-methylimidazolium Chloride Probed by High Pressure Raman Spectroscopy

International Journal of Molecular Sciences

Hai-Chou Chang¹  Chao-Yen Chang¹  Jong-Chang Su¹  Wen-Chi Chu¹  Jyh-Chiang Jiang² 

[1]Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan

[2]Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

关键词: Raman spectroscopy;    High pressure;    1-Butyl-3-methylimidazolium chloride;   

DOI  :  10.3390/i7100417

来源: mdpi

【 摘 要 】

The behavior of 1-butyl-3-methylimidazolium chloride has been investigated by Raman spectroscopy as a function of hydrostatic pressure. Under ambient pressure two rotational isomers (GA and AA forms) of the 1-butyl-3-methylimidazolium cation coexist in the ionic liquid state. As the supercooled liquid was compressed from ambient to 0.9 GPa, the contribution of the GA conformer decreases in intensity as the pressure was elevated. A new high pressure phase is formed above the pressure of 1.5 GPa. This new high pressure phase of 1-butyl-3-methylimidazolium chloride arises from perturbed GA conformer, i.e., distorted Crystal 2. Crystal 1 form (AA form) is known as a thermodynamically stable form under ambient pressure. Nevertheless, crystal 1 form is switched to a metastable state under the condition of high pressure.

【 授权许可】

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