Interactions of sodium salicylate and β-cyclodextrin in water: A volumetric, ultraacoustic and optical study

Abstract

Present article reports the thermodynamic studies on standard transfer volumes and compressibilities of non-steroidal anti-inflammatory drug, sodium salicylate in 0.0005, 0.001, 0.004, 0.009, 0.0140 mol·kg−1 aqueous-β-cyclodextrin solutions at 303.15, 308.15 and 313.15 K. The transfer properties have been calculated from the standard partial molar volumes and compressibilities determined form the linear dependence of corresponding apparent molar properties over the drug concentration. Apparent molar properties have been calculated from measured density and ultrasonic velocity data. Further, the optical property, refractive index (n) of the studied drug solutions has been measured. In addition to this, the quantum mechanical calculations were performed using the DFT. The solvation energy (ΔESol), relative stabilization energy (ΔERel), complexation energy (ΔEComp) and change in the volume (ΔV) of the different complexes have been calculated. The results have been discussed in terms of the drug-solvent and drug-β-cyclodextrin interactions. The complex formation of sodium salicylate with β-cyclodextrin with dominating lateral interactions namely ion-hydrophilic/hydrophilic-hydrophilic or hydrogen bonding interactions has been confirmed from standard partial molar properties and computational studies.