Translational Diffusion in a Set of Imidazolium-Based Ionic Liquids [bmim]A and Their Mixtures with Water.

As the development of the work ( (10), 2362-2372), we have investigated the translational mobility in the same set of dried imidazolium-based ionic liquids (ILs) [bmim]A (A = BF, NO, TfO, I, Br, and Cl) in a wide temperature range using the NMR technique. It is shown that for the [bmim] cation, the temperature dependencies of product η do not follow the Stokes-Einstein relation for most systems studied, that is, the so-called "diffusion-viscosity decoupling" was realized. The correlation between local and translational mobility in pure IL of the [bmim][A] type was investigated using the data on NMR relaxation rates and diffusion coefficients.

Molecular Mobility in a Set of Imidazolium-Based Ionic Liquids [bmim]A by the NMR-Relaxation Method.

The detailed investigation of the local mobility in a set of dried imidazolium-based ionic liquids (1-butyl-3-methylimidazolium) in a wide temperature range and varying anions (BF, I, Cl, Br, NO, TfO) is presented. The measurements of temperature dependencies of the spin-lattice relaxation times of H and C nuclei are motivated by the need to obtain a fundamental characterization of molecular mobility of the substances under study, namely, to estimate the correlation times, τ, for the motion of individual molecular groups. In particular, it follows from obtained results that the mobility of the hydrocarbon "tail" is higher (smaller τ) than that of the imidazole ring, and this expected tendency is quantified.