Significant cation effects in carbon dioxide-ionic liquid systems

Abstract

Carbon dioxide-ionic liquid systems are of great current interest, and significant efforts have been made lately to understand the intermolecular interactions in these systems. In general, all the experimental and theoretical studies have concluded so far that the main solute-solvent interaction takes effect through the anion, and the cation has no, or only a secondary role in solvation. In this theoretical approach it is shown that this view is unfounded, and evidence is provided that, similarly to the benzene-CO2 system, dispersion interactions are present between the solute and the cation. Therefore, this defines a novel site for tailoring solvents to tune CO 2 solubility. Roles in solvation: The interactions between CO 2 and imidazolium-based ionic liquid (IL) cations are investigated by ab initio molecular dynamics simulations and static quantum chemical calculations. Cation-CO2 dispersion interactions play a structural role in such ILs (see picture), similar to those in the benzene-CO2 system. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.