Solvation behaviour of some amino acids in aqueous solutions of an antibiotic drug streptomycin sulfate at different temperatures: Volumetric, acoustic and viscometric approach

Abstract

The volumetric, acoustic and viscometric approach has been used for investigating the interactions of l-serine, l-threonine and l-leucine in aqueous solutions of an antimycobacterial drug, namely, streptomycin sulfate, over a temperature range of (305.15, 310.15 and 315.15) K at atmospheric pressure. The apparent molar volume, Vϕ, limiting apparent molar volume, V0ϕ, the slope, Sv, partial molar volume of transfer, V0ϕ, tr, limiting apparent molar expansivity, E0ϕ, and Hepler's constant, (∂2V0ϕ/∂T2)P, have been calculated from density data. The apparent molar isentropic compression, Kϕ,s, limiting apparent molar isentropic compression, K0ϕ,s, its slope, Sk, and partial molar isentropic compression of transfer, K0ϕ,s,tr, have been calculated from speed of sound data. The compression data is also used for calculating the number of water molecules hydrated, nH, to the amino acids. The viscosity data has been used to determine relative viscosity ηr, viscosity B-coefficients, temperature derivative of B-coefficients, dB/dT and viscosity B-coefficients of transfer, Btr. Solvation behaviour, of amino acids has also been computed. The calculated parameters have been discussed in terms of various solute–solute and solute–solvent interactions prevailing in these solutions. Further, a detailed insight into the physicochemical interactions, e.g., ion-hydrophilic and hydrophilic–hydrophilic interactions in the amino acids in conjunction with the drug along with the structure-making/structure-breaking tendency has been retrieved through the perusal of these calculated parameters.