Density, viscosity and electrical conductivity of four amino acid based ionic liquids derived from l-Histidine, l-Lysine, l-Serine, and Glycine

Amino acid ionic liquids (AAILs), as a kind of renewable and biocompatible ionic liquids, show special properties of strong polarity, strong hydrogen bonding ability, stable chiral center and excellent biodegradability, and share huge application potentials in almost all of the biological, medical, pharmaceutical and biotechnological processes. The investigation of physico-chemical properties of AAILs both in purity and interacting with molecular solvents highly contributes to understanding the huge application potential of AAILs in different fields of the chemical, pharmaceutical and petrochemical industries. This paper synthesized several AAILs of [VilmC3][His], [VilmC3][Lys], [VilmC3][Ser] and [VilmC3][Gly], by using l-Histidine, l-Lysine, l-Serine, and Glycine as anions, respectively. The obtained AAILs were characterized by 1H NMR analysis and TG-DTG analysis. The basic physical properties of density, dynamic viscosity, and conductivity were systemically measured. The apparent molar volume, limiting apparent molar volume, excess molar volume, isobaric expansivity coefficient and apparent molar expansivity were estimated from density. The viscosity deviation, the molar and limiting conductivities were calculated from dynamic viscosity and conductivity, respectively. Various models were used to correlate the experimental data, and the molecular interactions were discussed. The information obtained from this work serves as the basement to the AAILs application.