DFT Calculations of Isotropic Coupling Constants of Phenoxyl and Aroxyl Radicals

Sa？etak Hybrid density-functional calculations were carried out to corroborate the identity of phenoxyl radicals observed by EPR spectroscopy after oxidation of selected mono- and polyphenols with horseradish peroxidase/hydrogen peroxide or after alkaline autoxidation. Whereas quantitative correlations of experimental and theoretical coupling constants were less satisfactory, we could confirm formation of a bi-radical after initial oxidation of 2,4,6-trimethylphenol, the mesomeric structures of gallate ester aroxyl radicals and identify the radical site of a model gallotannin, hamamelitannin