A conformational study of hydroxyflavones by vibrational spectroscopy coupled to DFT calculations

The conformational preferences of a series of hydroxyflavones were studied by Raman and FTIR spectroscopies, coupled to Density Functional Theory calculations. Special attention was paid to the effect of hydroxyl substitution, due to its importance on the biological activity of these compounds. Their conformational preferences were found to be determined mainly by the orientation of the hydroxylic groups at C7 and within the catechol moiety, leading to the occurrence of distinct conformers in the solid state. A complete assignment of the experimental spectra was carried out for these molecules, in the light of their most stable conformers and the corresponding predicted vibrational pattern.

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► Full vibrational assignment of a series of dietary hydroxyflavones.
► Complete conformational analysis.
► Use of vibrational spectroscopy for establishing reliable structure–activity relationships (SAR’s).
► SAR’s will allow to understand the health-promoting ability of dietary compounds (phytochemicals).