Intramolecular charge transfer and hydrogen bonding interactions of nonlinear optical material N-benzoyl glycine: Vibrational spectral study

Near infrared Fourier-transform Raman (NIR FT-Raman) and Fourier-transform infrared (FT-IR) spectroscopy supported by density functional theoretical (DFT) computations have been employed to derive equilibrium geometry, vibrational wavenumbers and the first hyperpolarizability of the nonlinear optical (NLO) material N-benzoyl glycine. The influence of twisted intramolecular charge transfer (TICT) caused by the strong ionic ground state hydrogen bonding between charged species giving NBG crystal a non-centrosymmetric structure has been discussed. The intense low wavenumber H-bond Raman vibrations due to electron–phonon coupling and non-bonded interactions in making the molecule NLO active was analyzed based on the vibrational spectral features.