DFT investigation of physicochemical and antioxidant properties of fluorinated flavones

In the present research, the physicochemical properties including electronic and structural properties and antioxidant activity of six fluorinated flavone derivatives have been discussed using of density functional theory calculations. Benchmarking studies of the DFT-B3LYP/6-311 + G(d, p) computational method were done using experimental (HNMR)-H-1 and (CNMR)-C-13 data of flavones 2 and 5. The experimental and calculated spectral data are in very good agreement with R-2 < 92%. Using the DFT-B3LYP/6-311 + G(d, p) method, bond lengths and bond angles, intramolecular hydrogen interactions, EHOMO and E-LUMO, electrophilicity index, and reactivity against active oxygen radicals were investigated. The local electrophilicity indices were calculated for flavones 1-6. Three reactive centers can be considered for nucleophilic attack on flavones 1-6. The data showed that the most active center is C9 on the 4-pyrone ring, conducting the Michael reaction, and the presence of -CF3 group on these compounds increases the electrophilic properties of flavones 1-6. Using three mechanisms of hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and the sequential proton loss electron transfer (SPLET) mechanisms, antioxidant activity of the studied flavones was investigated and compared with data for phenol. The presence of intramolecular hydrogen bonds strongly affects the antioxidant properties. According to the above-mentioned mechanisms, antioxidant activity of studied flavones 1-6 is higher than that of phenol. The presence of fluorine atom has a significant effect on their physicochemical properties.