Pressure-induced crystallization of 1-butyl-3-methylimidazolium hexafluorophosphate

Abstract

We have investigated the pressure-induced crystallization of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) associated with the conformational changes of [bmim]⁺ by Raman spectroscopy. [bmim]⁺ has trans-trans and gauche-trans (GT) conformers of the butyl side chain at ambient pressure. Our result revealed that liquid to solid-phase transition occurs at 0.2–0.4 GPa region, where the GT conformer becomes dominant. We found that the GT dominant state continues up to 4 GPa.

Keywords:

• ionic liquids
• pressure-induced phase transition
• conformation
• Raman spectroscopy

Notes

^†This article was first presented at the joint IUCr commission on High Pressure 2012 – Quantum Beam Science Directorate Meeting ‘Advances in Crystallography at High Pressures’ International Symposium (IUCrHP2012/QuBS2012), 23–27 September 2012, Mito, Japan.