The pervasive solvent-separated sodium chloride ion pair in water-DMSO mixtures

摘要

Sodium chloride exists as a contact ion pair (CIP) as well as a solvent- separated ion pair (SSIP) in its solutions in water and in dimethyl sulphoxide (DMSO). In a mixture of these two solvents, the CIP is not formed in the two mixture compositions with Xdmso=0.35 and 0.21 and the ions stay as the SSIP near an interionic distance of 5.0A. This has been shown by constructing the ion-ion potentials of mean force and by following the ion-pair trajectories initiated at various initial ion-pair separations in the two solvent mixtures.