Abstract
The speed of sound (u)in conjunction with density (ρ) and viscosity (η) for amino acids l-glutamine and l-histidine in aqueous solutions of metformin hydrochloride (an anti-diabetic drug) (0.01, 0.07, and 0.13mol·kg−1) have been measured in the concentration range (0.02–0.20mol·kg−1) at (293.15, 298.15, 303.15, 308.15, and 313.15) K. In order to account for the consequences of drug–amino acid interactions, various acoustical parameters such as intermolecular free length (Lf), relative association (RA), specific acoustic impedance (Z), and molar sound number ([U]) have been evaluated from density and speed of sound data. Combined with viscosity values, the speed of sound data have been used to estimate parameters like relaxation time (τ), internal pressure (πi), molar cohesive energy (MCE)and free volume (Vf). The results of acoustical studies are substantiated with UV–Vis studies for ternary system (water+drug+amino acid). The different kinds of intermolecular interactions existing between different components of the mixture are found to be responsible for the varying trends in aforesaid different acoustic parameters.
•Temperature dependent acoustic and UV–Vis studies for drug–AA system have been carried out.•Intermolecular interactions in aqueous metformin hydrochloride–amino acid system have been investigated.•Strong solute–solvent interactions of the type dipole–dipole through H-bonding have been observed.•These interactions are stronger for histidine as compare to glutamine.•Bathochromic shift for both amino acids has been observed.