As the development of the work (J. Phys. Chem. B 2019, 123 (10), 2362−2372), we have investigated the translational mobility in the same set of dried imidazoliumbased ionic liquids (ILs) [bmim]A (A = BF 4− , NO 3 − , 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 Dη 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. The most recent hypothesis of "water pockets" in mixtures of IL with water is critically discussed. Considering the totality of data in the literature and obtained here, we propose a specific model of the microstructure which may be applied up to water concentrations of 80−90 mol % (the structure of water-rich solutions is out of our current consideration). To confirm the model, molecular dynamics simulations of "IL−water" mixtures were also carried out.

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 (BF4 –, I–, Cl–, Br–, NO3 –, TfO–) is presented. The measurements of temperature dependencies of the spin–lattice relaxation times of 1H and 13C 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, τc, for the motion of individual molecular groups. In particular, it follows from obtained results that the mobility of the hydrocarbon “tail” is higher (smaller τc) than that of the imidazole ring, and this expected tendency is quantified. The effect of the influence of an anion type on the cation mobility is also analyzed.

Characterization of protein solutions is of great importance for biophysical research, pharmaceutical industry, and medicine. Particularly, the monitoring of the protein aggregation is crucial at all stages of biotechnological production and in the diagnosis of dangerous diseases. The present work is focused on a study of prospects and possibilities of NMR relaxation of solvent nuclei for monitoring the state of proteins in solutions. The spin-lattice and spin-spin relaxation rates (R 1 and R 2) of solvent nuclei were measured in the solutions of a small globular protein, RRM2 domain of TDP-43 protein. The solvent was either H 2 O-or D 2 O-based buffer with pH 6.5 and contained 20 mM sodium phosphate and 150 mM NaCl. The relaxation rates of the solvent 1 H, 2 H, 23 Na, and 35 Cl nuclei in solutions of soluble and aggregated RRM2 domain of TDP-43 protein were studied. The aggregation was induced by mild oxidative stress, using treatment by hydrogen peroxide. It was found that aggregation of protein could be detected using NMR relaxation of 1 H nuclei. The observed CPMG dispersion for R 2 rates confirms the millisecond timescale for the hydrogen exchange between water and protein sites. The correlation times and binding constants for sodium and chlorine ions were estimated using concentration dependences for relaxation rates (23 Na, 35 Cl). The relaxation rates of solvent nuclei are sensitive to the presence of protein in solution even at low protein concentrations, and the relaxation rates of different nuclei reflect various aspects of the state of the protein.