Charge templates in aromatic plus ionic liquid systems revisited: NMR experiments and molecular dynamics simulations

The mutual solubilities of [C2C1im][Ntf2] ionic liquid and aromatic molecules (benzene and its fluorinated derivatives) can be correlated to the dipolar and quadrupolar moments of the latter molecules. This fact can be interpreted as a consequence of the charge-induced structuration of the IL ions around the aromatic molecules. In this paper we demonstrate that we can follow the above-mentioned structural changes in the mixtures using different NMR-based techniques, namely 1D (1)H and (13)C NMR and 2D (1)H-(1)H NOESY NMR spectroscopy. These have been complemented by more detailed structural analyses of the different (IL plus aromatic solute) mixtures using MD simulations. Such systematic studies included eight systems, namely mixtures of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid with benzene, fluorobenzene, 1,2-difluorobenzene, 1,4-difluorobenzene, 1,3,5-trifluorobenzene, 1,2,4,5-tetrafluorobenzene, penta-fluorobenzene, and hexafluorobenzene.