Exploring low temperature behavior of superacid-based ionic liquids through in situ XRPD analysis

Superacid-based Ionic Liquids (ILs) hold promise for diverse applications such as electrolytes for battery and fuel cells and as polar solvents both for high-temperature reactions and technological applications. Their inherent stability further contributes to their appeal. Based on a previous paper by some of us, the behavior of three ILs were studied by in situ X-ray powder diffraction (XRPD) under controlled temperature ramps, shedding light on their behavior at lower temperatures, an aspect previously unexplored, marking a significant stride towards understanding the fundamental properties of these intriguing systems, opening roads for their tailored applications in diverse technological domains. Each IL is synthetized from a unique superacid (methanesulfonic, trifluoroacetic and triflic) in combination with triethylamine base. DSC analysis suggested that at the lower temperatures new phases could be formed. Their presence was revealed combining XRPD and principal component analysis (PCA). Most of the newly identified structures were then solved by XRPD data.