Refractive index, speed of sound, FT-IR and computational study of intermolecular interaction between binary mixtures of 1,8-cineole with o-, m- and p-cresol at 303.15, 308.15 and 313.15 K

Abstract

Refractive indexes (nD) and speed of sound (u) have been experimentally measured for binary mixtures of 1,8-cineole+o-, m- and p-cresol at entire composition range at 303.15, 308.15 and 313.15K at atmospheric pressure. The deviation in refractive index (∆nD), molar refraction (Rm) and deviation in molar refraction (∆Rm) has been calculated using experimentally measured values of the refractive index. Similarly, from the measured values of speed of sound (u), some of its related properties like deviation in speed of sound (∆u), isentropic compressibility (ks), deviation in isentropic compressibility (∆ks), acoustic impedance (z), deviation in acoustic impedance (∆z) have been calculated. The partial molar isentropic compressibility K−s,m,io, excess partial molar isentropic compressibility K−s,m,io,E, apparent molar isentropic compressibility (Ks,m,Φ,i) have been also calculated. The values of apparent molar isentropic compressibility (Ks,m,Φ,i) have been fitted with the Redlich-Rosenberg-Mayer equation to get limiting apparent molar isentropic compressibility (Kos,m,Φ,i) and Sk and Bk empirical parameter values. All these calculated results were fitted with the Redlich-Kister polynomial equation. The FT-IR spectra of pure and their binary mixtures are also studied. The geometrically optimization, harmonic vibrational wave numbers, bond characteristics and single point energy has been theoretically calculated using density functional theory (DFT-B3LYP) method with 6-31+G(d,p) basis sets for pure components and their binary mixtures. Positive values of ∆nD, ∆u, ∆z and negative values of ∆Rm, ∆ks and K−s,m,io,E support for the presence of strong intermolecular interactions between components of these binary mixtures.