Dynamical Behavior and Local Interactions in a Binary Mixture between Room-Temperature Ionic Liquid and Organic Solvent

M Armstrong and K Tashiro and M Jitvisate and S Rimjaem and P Nimmanpipug, ACS OMEGA, 10, 62477-62488 (2025).

DOI: 10.1021/acsomega.5c04701

Elucidation of innate interactions between room-temperature ionic liquids (RTILs) and organic solvents can enable the effective use of binary solvent systems, particularly in electrotunable lubricants, electrolytes in energy storage devices, solvents for synthesis, and catalysis, where solubility and ion concentration are key to achieving optimal performance. Molecular dynamics simulations using a polarizable force field and a non-polarizable force field for 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (C2mimNTf2) mixed with dimethyl sulfoxide (DMSO) have been carried out. Trends in local structure and dynamics behavior as a function of the mole fraction of DMSO (x DMSO) were examined. The cis-trans conformational transition around the S-N bonds of RTIL molecules was found to develop a more scattered orientation at a high DMSO concentration range (x DMSO = 0.70-0.95). The NTf2- anion and DMSO share the same preferred interaction site at the imidazolium ring of C2mim+. Hydrogen bonding interactions are found to predominantly exchange from C2mim+NTf2- to C2mim+DMSO at around x DMSO = 0.80.

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