Reducing Power of Simple Polyphenols by Electron-Transfer Reactions Using a New Stable Radical of the PTM Series, Tris(2,3,5,6-tetrachloro-4-nitrophenyl)methyl Radical

The synthesis and characterization of a new radical and its use for testing the antioxidant activity of
polyphenols by electron transfer are reported. This new and stable species of magnetic nature, tris(2,3,5,6-tetrachloro-4-nitrophenyl)methyl (TNPTM) radical, has been characterized by electron paramagnetic resonance and its molecular structure determined by X-ray analysis. This new radical of the
PTM (perchlorotriphenylmethyl) series, unlike 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, is stable
in conditions of hydrogen abstraction reactions. TNPTM radical is able to discriminate between the
antioxidant activities of catechol and pyrogallol in hydroxylated solvent mixtures such as chloroform/methanol (2:1). These features determine the antioxidant/pro-oxidant character and the biological activities
of natural and synthetic flavonoids.