Solubility and Antioxidant Activity of 1,2-Dihydro-2-Methyl-2-Phenyl-3H-Indole-3-One-1-Oxyl Hosted at Randomly Methylated-B?etacyclodextrin: A Computational Investigation

In this work, the mechanism of the formation of a radical from 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl has been studied theoretically by the B3LYP/6-31G(d) method as well as the global descriptors of its reactivity have been calculated. The formation of an inclusion complex (stoichiometry 1:1) between the radical form of 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl and the randomly methylated beta-cyclodextrin was also studied by B3LYP-D3/6-31G(d) method. The results obtained show that the formation of the radical is ensured by the HAT mechanism according to the BDE energies obtained in vacuum and in water. Formation of the inclusion complex according to the two models C1 and C2 leads to an increase in solubility and improve antioxidant activity of 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl radical which is agreed well with experimental results. Finally, intermolecular interaction such us H-bonds and van Der Waals interactions are the major contribution of inclusion complex stability.