Molecular dynamics simulations are used to investigate the molecular mechanism of ion pair association between the Room-Temperature Ionic Liquid(RTIL) ions in aqueous solutions. We choose commonly studied Imidazolium based ionic liquids. We used potential of mean force(PMF) calculations to explore the ion pair association and its dependence on the anion as well as cation chain length. Our PMF studies show a stronger interaction between ion pairs, for the systems involving [DMIM] as cation compared to that of the systems containing [OMIM], indicating a decrease in ion-pair association with the increase in alkyl tail length of the cation. Our analysis of rotational dynamics of cations shows that the time scales for molecular reorientation are longer for cations with longer alkyl tails. Kinetics of Ion pair dissociation using different rate theories is also investigated.

Ion pair association among room-temperature ionic liquid ions in aqueous solutions

246th National Meeting (2013)

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