NICS: A possible new criterion to evaluate the structure-antioxidant activity relationship of phenolic compound

Our calculations have shown that a series of the studied monosubstituted phenol derivatives containing substituents with different electronic effects on the ortho-, meta- and para-positions, show a direct relationship between the H-abstraction of the hydroxyl groups and the low values of nucleus-independent chemical shift (ANICS) activity, and these in turn are related to antioxidant activity, hence are in the lowest values of the enthalpy of dissociation, and this is demonstrated by the values of small ANICS. All calculations of bond dissociation enthalpy (BDE) and the criterion of aromaticity (ΔNICS) were calculated using density functional theory (DFT) methods.