Experimental Signature of Microheterogeneity in Ionic Liquid-H2 O Systems and Their Perturbation by Adding Li(+) Salts: A Pulsed Gradient Spin-Echo NMR Approach

Abstract

Distinct microheterogeneity has been observed in the [OMIM]Br-H2 O system, which is interestingly perturbed by the addition of Li(+) salts, indicating unusual diffusivity of [OMIM]Br and H2 O molecules. However, the diffusional dynamics of water clusters show contrasting salting behavior at higher concentrations of Li(+) salts, following the classical salting phenomenon in lower amounts. In contrast, the existing microheterogeneity in the [BMIM]Br-H2 O system is weak enough to show any perturbation caused by the Li(+) salts on the NMR time scale.

Keywords: ionic liquids; lithium; microheterogeneity; salt effect; viscosity.