Molecular Interaction Studies of an Antidepressant Drug with Imidazolium-Based Ionic Liquids in an Aqueous System: A Volumetric, Acoustic, and Viscometric Approach

To study and comprehend the molecular interactions between ionic liquids (ILs) such as 1-ethyl-3-methylimidazolium bromide [EMIm]Br, 1-butyl-3-methylimidazolium bromide [BMIm]Br, and 1-hexyl-3-methylimidazolium bromide [HMIm]Br, and the antidepressant drug-nortriptyline hydrochloride (NTPH), we have examined the volumetric, acoustic, and viscometer properties of the binary and ternary solutions of different concentrations at different temperatures 288.15-318.15 K in the temperature interval of 10 K. The intermolecular interactions have been appraised and identified on the basis of different parameters, i.e., apparent molar properties (V-Phi, K-s,(Phi)), limiting apparent molar properties (V-Phi(o), K-s,Phi(o)), viscosity coefficients A and B, limiting apparent molar transfer properties (V-Phi,tr(o), K-s,Phi,tr(o)), viscosity B-coefficient of transfer (B-tr). Pair and triplet interaction coefficients are also determined using McMillan-Mayer theory. Based on the cosphere overlap model, the positive transfer values (V-Phi,tr(o), K-s,Phi,tr(o)) demonstrate that ionic-hydrophilic and hydrophilic-hydrophilic interactions are dominant between NTPH-IL solutions. Additionally, the strength of these interactions increases as the alkyl chain length of the imidazolium ionic liquid increases. Furthermore, the negative values of temperature derivatives of B-coefficients (dB/dT) and the positive values of Hepler's constant confirms the structure making nature of NTPH.