DFT, FTIR, Raman and NMR study of 1-methyl-8-oxyquinolinium betaine

1-Methyl-8-oxyquinolinium betaine, 8QB, has been characterized by FTIR, Raman, 1H and 13C NMR spectra and B3LYP calculations with 6-31G(d,p) and 6-311G(d,p) basis sets using the conductor-like screening continuum solvation model (COSMO). The calculated geometrical parameters are in satisfactory agreement with the X-ray data. The C(8)–O(18) bond has enhanced double bond character and is solvent dependent as expected. The probable assignments of the experimental FTIR solid spectrum have been made on the basis of B3LYP calculated frequencies in vacuum. Both 1H and 13C chemical shifts are solvent and in D2O also concentration dependent. Correlations between the experimental 1H and 13C NMR chemical shifts of 8QB in solutions and the GIAO/B3LYP/6-311G(d,p) calculated magnetic isotropic shielding tensors (σcal) using the screening solvation model (COSMO), δexp = a + bσcal, are reported.