Revisiting Ether-Derivatized Imidazolium-Based Ionic Liquids

A series of ether-derivatized imidazolium halides have been prepared and characterized. Contrary to literature
reports, they are all crystalline solids and have melting points well above room temperature (50−100 °C).
Single crystals of the imidazolium salts, obtained in situ by slow cooling from their molten state to room
temperature, were analyzed by X-ray crystallography, revealing various anion−cation interactions in the solid
state. Exchange of the halides with [Tf2N]- yielded room temperature ionic liquids with viscosities that are
comparable to related 1-alkyl-3-methylimidazolium ionic liquids. Density functional theory combined with
IR spectroscopy has been used to analyze the role of functionalization of the imidazolium side chain on the
formation of the molecular and supramolecular structure of the compounds and its possible impact on their
physical properties.