We present here the possibility of forming triphilic mixtures from alkyl‐ and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domains—polar and nonpolar—three stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self‐associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long‐range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment.
We report for the first time joined energy dispersed x-ray and neutron diffraction experiments on a series of (both protiated and selectively deuteriated) 1-alkyl-3-methylimidazolium hexafluorophosphate salts (alkyl = butyl, hexyl, octyl) at ambient conditions. The x-ray experimental data are used to optimize the interaction potential used for running molecular dynamics simulations on these systems. Such a potential leads to a good description of neutron scattering data from the samples without additional refinement, thus further validating the potential definition. The molecular dynamics simulations were used to access microscopic information on the morphology of the proposed systems, thus probing the role played by alkyl chain length on the structure. The comparison of x-ray weighted and neutron-weighted computed diffraction patterns allows the rationalization of several diffraction features. Further insight into cation–anion coordination and alkyl chain conformational equilibrium is provided on the basis of the MD-derived snapshots, confirming and extending previously obtained results on these issues.
6 August 2019 in Journal of Chemical Information and Modeling