# Synthesis, Physical and Ion-Conducting Properties of 1,2,3-Triazolium Ionic Liquids

## TL;DR

This paper describes the synthesis and properties of new 1,2,3-triazolium ionic liquids with various substituents, highlighting their thermal stability and ionic conductivity.

## Contribution

The study introduces a novel series of 1,2,3-triazolium ionic liquids with diverse substituents and evaluates their structure-property relationships.

## Key findings

- The PEGylated TIL derivative shows the lowest glass transition temperature (−76 °C) and highest thermal stability (345 °C).
- The same TIL derivative exhibits the highest ionic conductivity (6.5 × 10−4 S cm−1 at 30 °C).

## Abstract

1,4-Disubstituted 1,2,3-triazoles are readily obtained by copper(I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition (CuAAC)—the most widespread illustration of click chemistry to date. 1,2,3-Triazoles form a vast and easily accessible library of precursors for synthesizing 1,2,3-triazolium ionic liquids (TILs). A series of four 1,3,4-trisubstituted TILs with N-1-n-octyl, N-3-methyl and different C-4 substituents (i.e., aromatic, aliphatic, PEGylated and perfluorinated groups) is synthesized in two steps involving: (i) CuAAC to generate 1,2,3-triazole precursors and (ii) N-alkylation of the 1,2,3-triazole groups with methyl iodide to afford the corresponding 1,2,3-triazolium salts with iodide counter-anions. A thorough investigation of the correlations between structure and properties is carried out using NMR spectroscopy, high-resolution mass spectrometry, differential scanning calorimetry, thermogravimetric analysis and broadband dielectric spectroscopy. The PEGylated TIL has also undergone ion metathesis to produce the TIL analogue with a bis(trifluoromethylsulfonyl)imide counter-anion. Of all the synthesized TILs, this derivative exhibits the lowest glass transition temperature (Tg = −76 °C), the highest thermal stability (Td10 = 345 °C) and the greatest ionic conductivity (σDC = 6.5 × 10−4 S cm−1 at 30 °C under anhydrous conditions).