NMR is widely used to study chemical, physical and biological processes in ionic liquids (ILs). We present results from nuclear Overhauser effect experiments designed to probe specific interactions between the IL molecular ions, as well as between these ions and solutes in the ILs. In particular, we have studied ILs that pair 1-alkyl-1-methylpyrrolidinium and 1-alkyl-3-methylimidazolium cations with bis(trifluoromethylsulfonyl)amide and fluoralkylphosphate anions. Our studies of ion-solute interactions focus on electro-active species including metallocenes and photosensitizers such as Ru(II)(bpy)3. Clear differences in the local solvation environment are observed between ILs cations with short alkyl chain substituents (such as ethyl or butyl) and cations with long alkyl groups (such as octyl or decyl). Pulse gradient spin echo experiments are used to characterize the self-diffusion of the IL molecular ions and the solutes. We find the self-diffusion of the redox-active solutes is retarded by about 10% for each charge for solutes with 0, +1 and +2 overall charge. Our goal is to determine how ion size, charge, amphiphilicity, and other properties determine solvation and interactions in ILs.

NMR studies of interactions and solvation in ionic liquids

246th National Meeting (2013)

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