Journal of Chemical Thermodynamics, Vol.125, 278-295, 2018
Molecular interactions of some amino acids in aqueous 1-butyl-3-methylimidazolium bromide solutions at different temperatures: A volumetric approach
Apparent molar volumes, V-(empty set) of amino acids i.e. glycine, L-alanine, L-serine, L-threonine and DL-alpha-aminobutyric acid in pure water and in aqueous solutions of imidazolium based ionic liquid, 1-butyl-3-methylimidazolium bromide, [BMIm] [Br] were determined from precise density measurements at temperatures T = ( 288.15-318.15) K and at atmospheric pressure. Partial molar volumes V-2(o) and partial molar volumes of transfer, Delta V-tr(2)o of amino acids in aqueous [BMIm] [Br] solutions have been obtained from the V-(empty set) data. The V-2(o) values follow the order: L-threonine > DL-alpha-aminobutyric acid > L-serine > L-alanine > glycine. Positive Delta V-tr(2)o values for all the studied amino acids indicate the dominance of hydrophilicionic interactions between amino acids and [BMIm] [Br]. The partial molar expansibilities (partial derivative V-2(o)/partial derivative T)(P) and their second order derivatives (partial derivative V-2(2)o/partial derivative T-2)(P), volumetric interaction parameters, V-AB and V-ABB, hydration number, n(H) have been calculated. The charged end groups, V-2(o) (NH(+)3, COO-), side chain contributions of the amino acids, V-2(o) (R) and apparent specific volume, v((empty set)) have also been obtained from V-2(o) and V-(empty set) data. The results have been interpreted in terms of possible molecular interactions. (C) 2018 Elsevier Ltd.