Molecular interactions of glycine and L-alanine plus citrate buffer solutions at different temperatures: Volumetric, viscometric, and FTIR approach

Densities, rho, and viscosities, eta of glycine/L-alanine in water and in (0.10, 0.50, 1.00) mol.kg(-1) aqueous trisodium citrate buffer (Na3CB) solutions of pH 7.40 at T = (298.15 to 318.15) K have been measured by using vibrating tube digital density meter and suspended level Ubbelohde capillary viscometer, respectively, at atmospheric pressure i.e. 101.3 kPa. Thermodynamic parameters, i.e., phi(omicron)(nu), Delta(tr) phi(nu), viscosity B-coefficients, and Delta B-tr obtained from density and viscosity measurements have been used to unravel predominant forces among glycine/L-alanine and aqueous Na3CB solutions. Activation free energies, Delta mu(omicron#)(2) for the viscous flow of solutions, have been obtained by applying transition state theory to the viscosity B-coefficients values. The results are further supported by FTIR studies for glycine/L-alanine in water and aqueous Na3CB solutions of pH 7.40, revealing the intermolecular hydrogen bonding in these systems. Moreover, the results obtained from volumetric, viscometric, and spectroscopic studies provide valuable information on intermolecular interactions, influencing their efficacy in biological applications.