PF6－を対アニオンとしたイミダゾリウム系イオン液体の複雑な熱的相挙動とその分子レベルでの理解

摘要

Here we review our recent works on thermal phase behaviors of ionic liquids, 1-alkyl-3-methylimidazolium hexafluorophosphates ([Cnmim]PF6, n=1~4). Their complex thermal phase behaviors observed in calorimetric measurements were investigated at the molecular level using combined techniques of Raman spectroscopy, quantum chemical calculations, X-ray analyses, and nuclear magnetic resonance spectroscopy. It was demonstrated that the conformational flexibility of the side chain in the cation played a key role for thermal phase behaviors of some ILs as represented by [C4mim]PF6, nevertheless, which was not always the case for others as evidenced in [C1mim]PF6 results.