Synthesis and physical properties of new low-viscosity sulfonium ionic liquids.

Several new sulfonium ionic liquids (ILs) with dicyanamide ([DCA]⁻) and bis(trifluoromethylsulfonyl)imide ([TFSI]⁻) counter anions have been synthesized. Their viscosity and ionic conductivity values were determined. The ILs with [DCA]⁻ were previously prepared by the metathesis reaction involving silver dicyanamide (AgDCA). We report here a very convenient and much less expensive method using an ion-exchange resin. The structures of these ILs have been confirmed by ¹H-NMR, ¹³C-NMR, and elemental analysis. Some of these sulfonium ILs displayed low viscosity (< 30 cP) and high ionic conductivity (> 10 mS cm⁻¹). A concluding remark on structure-property relationship has also been drawn involving alicyclic and cyclic sulfonium cations vs. [DCA]⁻ and [TFSI]⁻ anions. [ABSTRACT FROM AUTHOR]