Why are aromatic compounds more soluble than aliphatic compounds in dimethylimidazolium ionic liquids? A simulation study

Molecular dynamics simulations of solutions of benzene in dimethylimidazolium chloride and dimethylimidazolium hexafluorophosphate have been performed with a view to answering the question posed in the title. The difference between the chemical potential of a normal model of benzene and one with no charges was found to depend on the solvent but is at least 4 k(B)T. This difference is sufficient to account for the observed solubility differences. There are substantial changes in the local structure around benzene with and without charges. (C) 2003 Elsevier Science B.V. All rights reserved.