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 ( 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.