Hydroxyl Functionalized Pyridinium Ionic Liquids: Experimental and Theoretical Study on Physicochemical and Electrochemical Properties

Abstract

Structurally modified hydroxyl functionalized pyridinium ionic liquids (ILs), liquid at room temperature, were synthesized and characterized. Alkylated N-(2-hydroxyethyl)-pyridinium ILs were prepared from alkylpyridines via corresponding bromide salts by N-alkylation (65–93%) and final anion exchange (75–96%). Pyridinium-alkylation strongly influenced the IL physicochemical and electrochemical properties. Experimental values for the ILs physicochemical properties (density, viscosity, conductivity, and thermal decomposition temperature), were in good agreement with corresponding predicted values obtained by theoretical calculations. The pyridinium ILs have electrochemical window of 3.0–5.4 V and were thermally stable up to 405°C. The IL viscosity and density were measured over a wide temperature range (25–80°C). Pyridine alkyl-substitution strongly affected the partial positive charge on the nitrogen atom of the pyridinium cations, as shown by charge distribution calculations. On-going studies on Mg complexes of the new ILs demonstrate promising properties for high current density electrodeposition of magnesium.

Temperature-Dependent Electrochemical Stability Window of Bis(trifluoromethanesulfonyl)imide and Bis(fluorosulfonyl)imide Anion Based Ionic Liquids

“…Frontiers in Chemistry | www.frontiersin.org June 2022 | Volume 10 | Article 859304 10 reducing nature of the aromatic groups (Lethesh et al, 2019). It is worth mentioning that the temperature has only a negligible influence on the E c values of ether functionalised ILs.…”

Prospects and Design Insights of Neat Ionic Liquids as Supercapacitor Electrolytes

“…Another strategy to reduce the viscosity of the ILs is creating asymmetry in the cation by attaching alkyl substitution in the relevant positions of the cationic core. For instance, the viscosity of the pyridinium-based ILs, as previously discussed, can be significantly improved by attaching alkyl groups on the meta (3) position of the pyridine ring (Lethesh et al, 2019;Chellappan et al, 2011).…”

Novel two-photon absorption compounds with different organic cations: facile synthesis, photophysical properties, detection of viscosity, and selective imaging of the endoplasmic reticulum in living cells

“…1-(2-Hydroxyethyl)-4-methylpyridinium bromide ( 1a ) 25 and 1-(2-hydroxyethyl)-2-methylquinolinium bromide ( 1b ) 26 were synthesized according to the literature procedures. Other materials for the synthesis were purchased from commercial suppliers and used without further purification.…”