Molecular interactions in liquid mixtures containing o-cresol and 1-alkanols: Thermodynamics, FT-IR and computational studies

Abstract To investigate the nature and class of association forces between the pure liquids and their liquid mixtures, we have been analyzed with excess thermodynamic properties, spectroscopic and computational techniques. Although, the thermodynamic parameters such as excess volume (VE), isentropic compressibility (ks) and excess isentropic compressibility (ksE) have been calculated using the experimental data of density (ρ) and speeds of sound (u) of o-cresol with 1-alkanols (C3–C8) namely, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol at different temperatures from 25 to 40 °C with interval of 5 °C and at 0.1 MPa. The calculated excess and deviation functions have been fitted to the Redlich-Kister polynomial equation and the results have been analyzed in terms of molecular interactions and structural effects. However, the FT-IR data strongly supports the presence of intra- and inter molecular interactions between component molecules in the liquid mixtures through changing the stretching vibrational frequency of various functional groups of pure liquids. In addition, the hydrogen bonding features between o-cresol with different 1-alkanols were examined by using a molecular modeling program with the help of density functional theory (DFT - B3LYP), the optimized geometries, bond characteristics, natural bond orbital (NBO) and interaction energies of pure components and their complexes have been analyzed theoretically to recognize the nature and strength of interactions between o-cresol and 1-alkanols.