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Substituent Effects on OH Bond Dissociation Enthalpies and Ionization Potentials of Catechols: A DFT Study and Its Implications in the Rational Design of Phenolic Antioxidants and Elucidation of Structure–Activity Relationships for Flavonoid Antioxidants
Author(s) -
Zhang HongYu,
Sun YouMin,
Wang XiuLi
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200390052
Subject(s) - substituent , chemistry , catechol , moiety , density functional theory , bond dissociation energy , dissociation (chemistry) , medicinal chemistry , ionization energy , computational chemistry , stereochemistry , organic chemistry , ionization , ion
Density functional theory (DFT) on B3LYP/6‐31G(d,p) level was employed to investigate the substituent effects on OH bond dissociation enthalpies (BDEs) and ionization potentials (IPs) of catechols. It was revealed that the ortho hydroxyl of catechol was effective for the reduction of the OH BDE; however, the group had little influence on the IP. The para substituent effects upon OH BDEs and IPs for catechols were roughly the same as those for monophenols, and this gave the catechol moiety more potential than monophenol to be used as a lead compound in rational design of phenolic antioxidants. In addition, the 1,4‐pyrone effects on OH BDEs of catecholic rings A or B of flavonoids were also investigated. Although 1,4‐pyrone extended the conjugation system of flavonoids, it was not beneficial to reduce the OH BDE as a result of its electron‐withdrawing property. Thus, 1,4‐pyrone was unlikely to be favorable to enhance the H‐abstraction activity of flavonoids.