Antioxidant activity of fullerene C60 against OH free radicals: A quantum chemistry and computational kinetics study

In this work, we have studied the antioxidant activity of fullerene C60 towards OH free radicals, using quantum chemistry and computational kinetics methods. Energy profiles are calculated using different basis sets, and reaction rate constants are reported for the first time. The reaction rate constant for the addition of the OH radical to the fullerene C60 is reported for the first time. A value of 1.37 x 10 cm molecules s is obtained, which is close to the diffusion limit. Energetic considerations show that, once a first radical is attached to the fullerene cage, further additions are increasingly feasible, suggesting that fullerene can act as an OH radical sponge. The reaction energies oscillate as a function of the number of OH groups, because for even numbers of OH groups, reactions are barrier-less recombinations, while for odd numbers of OH groups they are radical-molecule reactions. After addition of the fourth OH radical, the energy favored path leads to a broken fullerene structure.