Comparison of three related imidazolium ionic liquids and their CS2 solutions.

The aim of this paper is to give examples showing how computer simulation can be used to obtain insight into the behaviour of ionic liquids. Three related ionic liquids with cations containing imidazolium rings and alkyl groups were studied, namely the monocationic liquids 1-butyl 3-methyl imidazolium triflimide ([C 4 H 9 CH 3 im][(CF 3 SO 2 ) 2 N]), 1-octyl 3-methyl imidazolium triflimide ([C 8 H 1 7 CH 3 im][ (CF 3 SO 2 ) 2 N]) and the dicationic liquid ([C 8 H 1 6 (CH 3 im) 2 ][(CF 3 SO 2 ) 2 N] 2 ). We find that the local structure of the liquids is similar in the dicationic and the C 4 liquid but nanophase separation occurs in the C 8 monocationic liquid, making the latter the odd one out for local structure. In contrast, for dynamical properties it is the liquid containing the dication which differs from the other two liquids showing that the dynamical properties are not necessarily correlated with equilibrium structure. The results of simulations of a probe molecule, CS 2 , in the three liquids are compared. [ABSTRACT FROM AUTHOR]