13C NMR relaxation studies of ionic liquids

A new method of obtaining molecular reorientational dynamics from 13 C spin-lattice relaxation data of aromatic carbons in viscous solutions is applied to the cation and anion of the ionic liquid, l-ethyl-3-methyl-imidazolium butane-sulfonate ([EMIM]BSO 3 ). Rotational correlation times are compared with viscosity data and indicate several [EMIM]BSO 3 phase changes over the temperature range from 278 to 328 K. Chemical shift anisotropy values are obtained for the ring and immediately adjacent methylene and methyl carbons in the imidazolium cation and for the three carbon atoms nearest to the sulfonate group in the anion.