Conversion of flavonoids and their conformation by NMR and DFT

Wide range of various biological activities of chalcones motivated the syntheses of three chalcone derivatives. The conversion to flavanones was confirmed by 1 H- nuclear magnetic resonance (NMR) spectral data. The reason for the aforesaid conversion was elucidated based on the potential energy values of the derivatives, calculated using the density functional theory based on the Hatree-Fock method with B3LYP functional and the 6–31G* basis set. The rate constants of the derivatives were obtained from the NMR data, and the relevant transition states were considered to explain the relationship between the rate constants and the potential energy differences. These findings can help us predict the molecular stabilities of flavonoids, including chalcones and flavanones, using density functional theory calculations.