Structural and vibrational studies on (E)-2-(2-hydroxy benzyliden amino)-3-phenyl propionic acid using experimental and DFT methods

The structural and spectroscopic properties of (E)-2-(2-hydroxy benzyliden amino)-3-phenyl propionic acid ((E)-2-HBAPPA) has been investigated by using theoretical and experimental methods. Using the computational studies the most stable conformer was identified. Density functional theory (DFT) calculations of 16 (E)-2-HBAPPA conformers have been performed to find the optimized structure and the computed vibrational wavenumbers of the most stable one. The FT Raman and FT-IR spectra of (E)-2-HBAPPA molecule have been recorded and analyzed. A detailed interpretation of the FT-IR, FT-Raman and harmonic wavenumbers obtained at B3LYP/6-311++G(d,p) level was reported. The vibrational assignments were studied using TED method. Intra-molecular charge transfer between nitrogen and hydroxyl hydrogen (CN⋯HO) has been studied. First order hyperpolarizability (β0) has been calculated. Electronic excitation of (E)-2-HBAPPA was recorded in the visible region and compared with calculated TD-DFT results.