Aggregation models of potential cyclical trimethylsulfonium dicyanamide ionic liquid clusters.

Raman and infrared spectra of trimethylsulfonium dicyanamide [(CH(3))(3)SN(CN)(2)] are reported and accurately reproduced by DFT methods (B3LYP and B3PW91), MP2, and MP3, and to a lesser extent by the RHF method. The (CH(3))(3)SN(CN)(2) ionic liquid forms two isomeric dimers that are of cyclic structure, one of which is 13 kcal/mol lower in energy than the other. Both isomeric cyclic pairs (versions 1 and 2), [(CH(3))(3)SN(CN)(2)](2), have the potential to further combine and form a common structure containing four pairs of (CH(3))(3)SN(CN)(2). This structure can then conceivably undergo a stacking procedure to form extended ionic liquid nanotubes of eight ionic liquids, [(CH(3))(3)SN(CN)(2)](8). The possible formation of gas phase ionic liquid clusters of two, four, and eight trimethylsulfonium dicyanamide ionic liquids is supported by highly exergonic free energy changes obtained from B3LYP/(6-311+G(d,p)) density functional calculations.

Revealing the influence of the strength of coulomb interactions on the viscosity and interfacial tension of ionic liquid cosolvent mixtures.

Within this work, viscosity and interfacial tension of selected ionic liquid cosolvent mixtures, [EMIM][EtOSO3] (1-ethyl-3-methyl-immidazolium ethyl sulfate) with water and ethanol, were studied as a function of composition by surface light scattering (SLS) and the pendant drop method in a consistent manner, allowing a close insight into the nature of interactions. Here, we show that the viscosity behavior clearly reflects the bulk structure of the ionic liquid cosolvent mixtures and correlates to the fluid structure at the phase boundary. In contrast to former work, we found the viscosity of ionic liquid [EMIM][EtOSO3] to be decreasing the stronger by small amounts of the cosolvents and the lower their dielectric constant. Furthermore, two distinct trends for the dependence of the viscosity on the cosolvent concentration were resolved. These were assigned to ion-dipole interactions dominating in the salt-rich region and to dipole-dipole interactions in the diluted one. A crossover between both regions is reflected by the interfacial tension data, where it seems that up to a "critical" concentration almost no cosolvent is present at the phase boundary.

Trialkylsulfonium dicyanamides--a new family of ionic liquids with very low viscosities.

Trialkylsulfonium dicyanamides show surprisingly low viscosities down to -20 degrees C and are therefore highly interesting liquid materials for separation processes and electrolyte applications at low temperatures.