Unravelling various types of non-covalent interactions of benzyl amine with ethers in n – hexane at 303.15K by ultrasonic and DFT methods

Physicochemical behaviour of n – hexane solutions containing benzyl amine (BA) and alicyclic ethers in the concentration range 0.02M–0.20 M is extensively studied through acoustical (experimental) and Density Functional Theory (DFT) methods and the nature of non-covalent molecular interactions existing in these ternary liquid mixtures have been investigated. Two structurally different ethers, namely, tetrahydrofuran (THF) and 1,4-dioxane (DIOX) are used. Ultrasonic velocity (u) at 2 MHz frequency, density (ρ) and viscosity (η) are measured for the ternary liquid systems at different concentrations andat 303.15 K. The existence of strong BA – ether non-covalent interaction and formation of hydrogen bonded complexes is identified in both the systems through the variations in acoustical and excess thermo-acoustical parameters with concentration. The influence of structure of ether on the strength of molecular interaction has been analysed through the calculation of formation constants of these complexes computed using Kannappan equation. An attempt has been made using meta hybrid density functional theory to confirm the existence of hydrogen bonded complexes in these two systems through the computed interaction energies and hydrogen bonding parameters. Computational investigation shows CH---π dispersive interactions in these complexes in addition to the classical hydrogen bonding.