Theoretical and experimental studies on the energetic, structural and some other relevant physicochemical properties of the antioxidant tyrosol (1), hydroxytyrosol (1OH) molecules and the corresponding radicals 1 rad• and 1O rad • are reported in this work. The experimental values of the gas-phase enthalpy of formation, Δ f H m 0 (g), in kJ•mol −1 , of 1 (−302.4 ± 3.4) and 1OH (−486.3 ± 4.1) have been determined. Quantum chemical calculations, at DFT (M05-2X) and composite ab initio G3 and G4 levels of theory, provided results that served to (i) confirm the excellent consistency of the experimental measurements performed, (ii) establish that the stabilizing effect of H-bond of hydroxyethyl chain and aromatic ring (OH•••π interaction) is smaller in radicals than in parent molecules, (iii) deducecombining experimental data in isodesmic reactionsΔ f H m 0 (g) of radicals 1 rad • (−152.3 ± 4.4 kJ• mol −1 ) and 1O rad • (−370.6 ± 3.8 kJ•mol −1 ), (iv) estimate a reliable O−H bond dissociation enthalpy, BDE of 1 (368.1 ± 5.6 kJ•mol −1 ) and of 1OH (333.7 ± 5.6 kJ• mol −1 ), and (v) corroborateusing "BDE criteria"than 1OH is a more effective antioxidant than 1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.