A DFT Study on Antioxidant Activity of Trolox and Substituted Trolox and Their Radicals

Density functional theory (DFT) at B3LYP/6-311G* level was employed to calculate antioxidant activity for Trolox[(+) -6-Hydroxy-2،5،7،8-tetramethylchromane-2-carboxylic acid] and Substituted Trolox. Bond dissociation energy (BDE)، HOMO-LUMO Gap energy، O-H charge differences and O-H bond lengths were calculated. The results are shown that the BDE values of substituated Trolox range from about 74 to 79 kcal/mol، demonstrating that Trolox is an effective chain-breaking antioxidant that prevents lipid peroxidation. Also The small value of gap and the distribution of π-like frontier orbital (HOMO and LUMO) delocalized through the whole molecule (Table 3) corroborate that Trolox and substituted Trolox could be a reactive systems.