Interaction studies of diglycine with aqueous solutions of sulphathiazole drug at different temperatures

Abstract

The interactions of diglycine with sulphathiazole drug as a function of temperatures have been studied using volumetric and acoustic parameters. Densities and speeds of sound of diglycine in (0.001, 0.002, 0.005 and 0.010) mol·kg^-1 aqueous solutions of sulphathiazole drug have been measured at five different temperatures of (288.15, 293.15, 298.15, 303.15 and 308.15) K under 0.1 MPa pressure. From density data, the apparent molar volume, the partial molar volume and the standard partial molar volume of transfer for glycine from water to aqueous sulphathiazole solutions have been calculated. Partial molar isentropic compression and partial molar isentropic compression of transfer have been calculated from the speed of sound data. Transfer parameters by using cosphere overlap model have been explained on the basis of ionic-hydrophilic, hydrophilic-hydrophilic, hydrophilic-hydrophobic and hydrophobic-hydrophobic group interactions. To draw the conclusion from the volumetric and acoustic data, limiting apparent molar expansion as well as the hydration numbers have been studied. The calculated values of thermal expansion coefficient have small and positive values. All of these derived or calculated parameters are explained to understand the solvation behaviour and various types of interactions born in the ternary solutions of (dipeptide + drug + water) due to change in structure. We have also attempted to examine the temperature and concentration dependence of such interactions.