Peculiar High-Pressure Phase Behavior of 1-Butyl-3-methylimidazolium Iodide

Abstract

We investigated the stability of the liquid phase of 1butyl-3-methylimidazolium iodide (hereafter abbreviated as [C 4 mim]-[I]) up to 16.7 GPa at room temperature. We observed a peculiar phase transition behavior in the [C 4 mim][I] sample. In particular, a glassy state was formed at ∼1.3 GPa; however, the reddish-brown precipitate was formed probably due to concentrated I 3 − or I 2 − species that were formed above 12 GPa; [C 4 mim][I] showed a pressure-induced partial crystallization from the glassy state. We concluded that the conformation of [C 4 mim] + is essential in iterative modulation to control the environmental formation of iodide precipitate.

High-Pressure Raman Study of n-Octane up to 15 GPa

“…These results implied that the amorphous phase is formed above 6 GPa along with the gauche conformer, whose population increases upon further pressurization (8–9 GPa). It should be noted that a certain quantity of the gauche conformer is required to prevent HP crystallization during the HP formation of glassy liquid in the conformational equilibrium. , …”

“…It should be noted that a certain quantity of the gauche conformer is required to prevent HP crystallization during the HP formation of glassy liquid in the conformational equilibrium. 58,59 Therefore, we explored the effect of the gauche conformer population on the conformational change of n-C 8 under HP. To gain more insights into the conformational change in n-C 8 , we decomposed the observed Raman C−C stretching and CH 3 rocking bands into several peaks and determined the integrated intensity using the curve-fitting analysis (Figure 3a).…”