A study of the molecular structure and spectroscopic properties of 3-hydroxy-2-quinoxalinecarboxylic acid by experimental methods and quantum chemical calculations

► Vibrational spectra, NMR and NBO analysis on 3-hydroxy-2-quinoxalinecarboxylic acid were reported. ► DFT calculated data such as IR and NMR were consistent with the experimental data. ► The structural, geometric, and electronic parameters were discussed based on the DFT calculations. ► The IR spectrum and NMR shifts suggested the presence of two tautomers and a dimer in the sample.