Vibrational spectroscopic, 1H NMR and quantum chemical computational study of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid

• IR, Raman, NBO analysis and MEP were reported.
• The wavenumbers are calculated theoretically using Gaussian09 software.
• The wavenumbers are assigned using PED analysis.
• The geometrical parameters are in agreement with the reported literature.

FT-IR, FT-Raman and 1H NMR spectra of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid were recorded and obtained data were confronted with the computed using Gaussian09 software package. DFT/B3LYP, B3PW91 calculations have been done using 6-31G* and SDD basis sets, to investigate the vibrational frequencies and geometrical parameters. The assignments of the normal modes are done by potential energy distribution (PED) calculations. The calculated first hyperpolarizability is comparable with the reported values of similar quinoline derivatives and is an attractive object for future studies of non-linear optics. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. MEP predicts the most reactive part in the molecule. The calculated 1H NMR results are in good agreement with experimental data.

The vibrational spectroscopic studies of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid in the ground state were reported experimentally and theoretically. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. The ring stretching modes in IR and Raman spectra are evidence for charge transfer interaction between the donor and the acceptor group through the π system. This along with the lowering of HOMO–LUMO band gap supports for the bioactivity of the molecule. MEP predicts the most reactive part in the molecule.Figure optionsDownload as PowerPoint slide