Thermodynamic Properties of Pyridine Based 1,3,4-Oxadiazole Scaffolds

The present work describes the synthesis, characterization, and thermo-acoustical parameters of binary solutions of 1-(2-(4-fluorophenyl)-5-(pyridin-4- yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(pyridin-2-yl)prop-2-en-1-one, (AS1-08) and 1-(2-(4- methoxyphenyl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(pyridin-2-yl)prop-2-en-1- one, (AS1-12) in dimethyl sulfoxide (DMSO) and N, N-dimethylformamide (DMF) were estimated. Viscosity, ultrasonic velocity, and density methods at different solvents (DMSO and DMF) and different temperatures (298.15, 308.15, and 318.15 K) were used during the experimental research work. Some acoustic parameters such as adiabatic compressibility (κs), intermolecular free path length (Lf), Rao’s molar sound function (Rm), Van der Waals constant (b), internal pressure (π), free volume (Vf) and solvation number (Sn) were calculated. The results obtained were interpreted in terms of solute-solvent and solute-solute interactions. The thermodynamic and various acoustical properties were determined at three different temperatures viz. (298.15, 308.15, and 318.15 K) at atmospheric pressure. Likewise, the similarity between experimental results of the binary solutions was studied to analyze how the change in the structural modification and solvent changes the values of Gibbs energy of activation (ΔG*), enthalpy of activation (ΔH*), and entropy of activation (ΔS*).