Properties and Intermolecular Forces of Ionic Liquid Mixtures: The Archetypical Case of [EMIM][BF₄] + [EMIM][EtSO₄]

The properties and nanostructure of the Double Salt–Ionic Liquid formed by the combination of [1-ethyl-3-methylimidazolium][BF4] and [1-ethyl-3-methylimidazolium][EtSO4] in the whole composition range are studied by a combined experimental and molecular simulation approach. The measured physicochemical properties were analyzed in terms of deviations of ideality and its relationships with intermolecular forces. Quantum chemistry calculations of model clusters were carried out to infer nanoscopic aggregations, considering several mechanisms of interactions. Classical molecular dynamics simulations were carried out as a function of mixture composition, pressure, and temperature, allowing one to characterize structural, dynamic, and energetic properties of the considered mixed ionic liquids. The possible mechanisms of interaction of the involved molecules with biological targets, proteins, and model cell membranes were also computationally studied to infer molecular level roots of toxicological effects of mixtures of ionic liquids. This multiapproach–multiscale study provides for the first time a global characterization of mixtures of ionic liquids.