title: Properties of Apolar Solutes in Alkyl Imidazolium-Based Ionic Liquids: The Importance of Local Interactions.
abstract: The solvation and the dynamic properties of apolar model solutes in alkyl imidazolium-based ionic liquids (IL) are studied by using all-atom molecular dynamics simulations. In regards to specific IL effects, we focused on the often used 1-ethyl-3-methyl imidazolium cation in combination with the anions tetrafluoroborate, acetate, and bis(trifluoromethanesulfonyl)imide. Our findings reveal that the size of the anion crucially influences the accumulation behavior of the cations, which results in modified IL solvation properties. Deviations between the different alkyl imidazolium-based IL combinations can be also observed with regard to the results for the radial distribution functions, the number of surrounding molecules, and the molecular orientation. The analysis of the van Hove function further shows pronounced differences in the dynamic behavior of the solutes. The simulations verify that the solute mobilities are mainly influenced by the composition of the local solvent shell and the properties of the underlying Lennard-Jones interactions. Additional simulations with regard to modified short-range dispersion energies for alkyl imidazolium-based ILs validate our conclusions.
authors.affiliation: Helmholtz-Institut Münster: Ionics in Energy Storage (IEK-12), Forschungszentrum Jülich, Münster (Germany).|Institute of Physical Chemistry, University of Münster, Münster, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Lesch
authors.affiliation: Institute of Physical Chemistry, University of Münster, Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Heuer
authors.affiliation: Institute for Computational Physics, University of Stuttgart, Stuttgart, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Holm
authors.affiliation: Institute for Computational Physics, University of Stuttgart, Stuttgart, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Smiatek
keywords: dispersion interactions; ionic liquids; molecular dynamics; solute dynamics; solvation