Molecular structure and vibrational spectra of quercetin and quercetin-5’-sulfonic acid

Molecular structures of quercitin and quercitin sulfonic acid have been determined by DFT quantum chemical calculations. FT-IR and FT-Raman spectra have been measured in the solid state and discussed in terms of B3LYP/6-311G(2d,2p) approach. The role of the hydrogen bonds in stabilization of their structures has been analyzed. The IR spectra were measured in the temperature range 5–300 K and the observed effects were used in the discussion of the hydrogen bond behavior.