Rotational isomers, vibrational assignments, HOMO–LUMO, NLO properties and molecular electrostatic potential surface of N-(2 bromoethyl) phthalimide

The stable isomer of N-(2 bromoethyl) phthalimide (NBEP) is determined. FT-IR (4000–400 cm−1) and FT-Raman (3500–100 cm−1) spectra were recorded on the solid phase of the molecule. Optimized geometrical parameters, vibrational wavenumbers of the stable isomer of NBEP are predicted by DFT/B3LYP/6-311++G(d,p). Reliable vibrational assignments associated with this molecule is made on the basis of total energy distribution (TED) results. The non-linear optical properties such as dipole moment, polarizability and first order hyperpolarizability of the title molecule are determined. Density plots over the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy surface directly identifies the donor and acceptor atoms in the molecule. It also provides information about the charge transfer within the molecule. To obtain chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule. Furthermore, reactive electrophilic and nucleophilic sites in the MEP surface are compared with the fitting point charges to electrostatic potential.