Rotational isomers, NBO and spectral analyses of N-(2-hydroxyethyl) phthalimide based on quantum chemical calculations

FT-IR and FT-Raman spectra of N-(2-hydroxyethyl)phthalimide (NHEP) have been recorded and analyzed. The stable isomer of NHEP is determined. The optimization geometry, intermolecular hydrogen bonding, and harmonic vibrational wavenumber of NHEP have been investigated with the help of B3LYP scaled quantum mechanical (SQM) method. The infrared and Raman spectra were predicted theoretically from the calculated intensities. Natural bond orbital (NBO) analysis indicates the presence of CO⋯H in the molecule. The calculated HOMO and LUMO are important in determining such properties as molecular reactivity. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with electrostatic potential (ESP).

► The minimum energy isomer geometry of N-(2-hydroxyethyl)phthalimide was examined. ► Observed FT-IR and FT-Raman spectra were compared with simulated infrared and Raman spectra. ► Polarizability calculations were performed. ► Density plot of HOMO–LUMO energy surface were plotted to identify the donor and acceptor. ► ESP surface has been plotted to obtain electrophilic and nucleophilic sites of the molecule.