Structure-Property Correlation in Phenyl N-Substituted Imidazolium Protic Ionic Liquids

Journal article, 2026

Establishing the correlation between chemical structure and physicochemical properties in protic ionic liquids is essential for their rationale design and application. In this context, the recently developed protic ionic liquids, benzylimidazolium bis(trifluoromethylsulfonyl)imide and n-phenylimidazolium bis(trifluoromethylsulfonyl)imide, are characterized with focus on phase behavior, thermal stability, intermolecular interactions, transport, and electrochemical properties, using a wide range of experimental methods. Compared to the chemical structure of the archetypal protic ionic liquid, 1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, the addition of a phenyl group to the cation results in reduced thermal stability, increased viscosity, stronger intermolecular interactions, and lower ionic conductivity, while maintaining comparable fragility, and a wider electrochemical stability window.