Better Than the Best Polar Solvent: Tuning the Polarity of 1,2,4- Triazolium-Based Ionic Liquids

In search of better replacement for highly polar volatile organic solvents, ionic liquids (ILs) with high polarity and high polarizability were synthesized using N-1 substituted 1,2,4-triazolium-based cation with trifluoromethanesulfonate as the counter anion. The temperature dependence polarity of the synthesized ILs has been investigated using solvatochromic dyes and expressed in terms of and Kamlet-Taft parameters (dipolarity/polarizability (π*), hydrogen bond donor acidity (α), and hydrogen bond basicity (β) in the range of (293.15−353.15) K. The introduction of the –SO3H functional group and triazole ring on the cation has revealed high polarity (ETN > 1.2) and high polarizability (π*> 3.2). Furthermore, to understand the extent of intermolecular interaction temperature dependence refractive indices have been measured in the temperature range (293.15−343.15) K and a positive correlation was observed with polarity parameter. Finally, the impact of structure variants in terms of the N-1 functionalized 1,2,4-triazole ring has been analyzed over the studied properties which is scrutinized to understand the solvation capability and intermolecular interaction in ILs.