PCM/TD-DFT analysis of 1-bromo-2,3-dichlorobenzene – A combined study of experimental (FT-IR and FT-Raman) and theoretical calculations

Abstract

This study represents an integral approach towards understanding the electronic and structural aspects of 1-bromo-2,3-dichlorobenzene (BDCB). The experimental spectral bands were structurally assigned with the theoretical calculation, and the thermodynamic properties of the studied compound were obtained from the theoretically calculated frequencies. The relationship between the structure and absorption spectrum and effects of solvents have been discussed. It turns that the hybrid PBE1PBE functional with 6-311+G(d,p) basis provide reliable λmax when solvent effects are included in the model.The NBO analysis reveals that the studied compound presents a structural characteristic of electron-transfer within the compound. The frontier molecular orbitals (HOMO–LUMO) are responsible for the electron polarization and electron-transfer properties. The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MESP). Besides, 13C and 1H have been calculated using the gauge-invariant atomic orbital (GIAO) method. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures. Furthermore, the studied compound can be used as a good nonlinear optical material due to the higher value of first hyper polarizability (5.7 times greater than that of urea (0.37289×10−30esu)). Finally, it is worth to mentioning that solvent induces a considerable red shift of the absorption maximum going from the gas phase, and a slight blue shift of the transition S0→S1 going from less polar to more polar solvents.