Physicochemical study of solute-solute and solute-solvent interactions of homologous series of α-amino acids in aqueous-isoniazid solutions at temperatures from 293.15 to 318.15 K

Drug-amino acid interactions have been investigated in aqueous media from the experimentally measured data of densities, rho, ultrasonic speeds, u and viscosities, eta of glycine, l-alanine, l-valine and l-isoleucine in water and in aqueous-isoniazid (1% and 2% isoniazid in water, w/w) solvents at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The rho and u data have been used to calculate the apparent molar volume, V-phi, limiting apparent molar volume, V-phi degrees apparent molar compressibility, K-s,K-phi, limiting apparent molar compressibility, K-s,K-phi degrees, transfer volume, V-phi,V-tr degrees, and transfer compressibility, K-s,K-phi tr degrees and hydration number, n(H). The viscosity data have been used to determine Falkenhagen Coefficient, A, Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Delta(mu 1)degrees(#) and per mole of solute, Delta(mu 2)degrees(#). These parameters have been discussed in terms of solute-solute and solute-solvent interactions prevailing in these solutions. A detailed insight into the structure making/breaking ability of the amino acids in these solutions has been retrieved through the close perusal of all these parameters. In addition, the values of V-phi degrees K-s,K-phi degrees B and Delta(mu 2)degrees(#) have been split into groups' contributions of the amino acids. Entropies, Delta S degrees(#) and enthalpies, Delta H degrees(#) of activation of viscous flow for amino acids in aqueous isoniazid solutions have been used to interpret interactions between the ions of amino acids and isoniazid. (C) 2019 Elsevier B.V. All rights reserved.