Solvent effects of 1-ethyl-3-methylimidazolium acetate: solvation and dynamic behavior of polar and apolar solutes

Abstract

We study the solvation properties of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]⁺[ACE]⁻) and the resulting dynamic behavior for differently charged model solutes at room temperature via atomistic molecular dynamics (MD) simulations of 300 ns length and 200 ns equilibration time. The solutes are simple model spheres which are either positively or negatively charged with a valency of one, or uncharged. The numerical findings indicate a distinct solvation behavior with the occurrence of well-pronounced solvation shells whose composition significantly depends on the charge of the solute. All the results of our simulations evidence the existence of a long-range perturbation effect in presence of the solutes. Our findings validate the dominance of electrostatic interactions with regard to unfavorable entropic ordering effects which elucidates the enthalpic character of the solvation process in ionic liquids for charged solutes.