Quantum chemical studies on structure of 1-3-dibromo-5-chlorobenzene

Molecular structure and vibrational frequencies of 1-3-dibromo-5-chlorobenzene (DBCB) have been investigated by density functional theory (DFT) calculations using Becke's three-parameter exchange functional combined with Lee–Yang–Parr correlation (B3LYP) and standard basis set 6-31G. DFT (B3LYP/6-31G) calculations have been performed giving energies, optimized structure, harmonic vibrational frequencies, IR intensities, and Raman activities. Raman and IR spectra of the DBCB were recorded and complete assignment of the observed vibrational bands of DBCB has been proposed. The predicted first-hyperpolarizability of DBCB is 1.221 × 10⁻³⁰ esu, which suggests that the title compound is an attractive object for future studies of non-linear optical properties. The impact of di-substituted halogens on the compound has also been discussed. Besides, molecular electrostatic potential (MEP), HOMO–LUMO analysis and NBO analysis were performed at DFT level of theory The UV–vis spectral analysis of DBCB has also been done which confirms the charge transfer of the title compound.