Molecular interactions between the mixtures of ethyl, propyl amines and 2-nitrobenzoic acid in 1,4-dioxane by DFT and dielectric relaxation analysis

Abstract

Molecular interactions between ethylamine, propylamine and 2-nitrobenzoic acid in a solvent 1,4-dioxane have been studied by DFT and Dielectric relaxation analyses. In the DFT method, the vibrational assignments are performed. Molecular structures are optimized theoretically, FMO, molecular surfaces and the values of Mulliken charges were obtained by the DFT method with B3LYP/6-311++G(d,p) basis set. The charge transfers in the molecules are confirmed by the HOMO and lowest LUMO. Different dielectric parameters like dielectric constant ε', dielectric loss ε″ at microwave frequency, static dielectric constant ε0 and dielectric constant ε∞ at optical frequency were determined over five different molar ratios (i.e., 1:3, 1:2, 1:1, 2:1, 3:1). Higasi’s methods single-frequency equation and Gopalakrishna’s single-frequency concentration variation methods are validated to measure multiple relaxation time τ1 to find the strength of hydrogen bonding, whereas the relaxation time τ2 for group rotation is used to find the steric interaction of proton donor. The values of relaxation time were found maximum at 1:1 (molar ratio) of ethylamine, propylamine with 2-nitrobenzoic acid.