| Abstract
| - The redox properties of a series of hydroxychalcones (a group of polyphenols abundantly present in plants)were investigated by cyclic voltammetry. As for many polyphenols, their beneficial properties have beenmainly related to their antioxidant activities, which in turn are directly associated to their redox behavior.Two types of radicals can be produced that are localized on either one of the two aromatic systems. Theirthermodynamic and kinetic parameters were extracted and compared to the predictions of density functionaltheory calculations. When at least one OH is present on each ring, their behaviors are dominated by theconjugated system: phenolic ring A−double bond−ketone, which is the only one to be oxidized. However,the redox properties of this conjugated system are strongly influenced by the presence of ring B. When anOH is present on ring B, an important feature is the existence of strong hydrogen bonding that remainsalmost unmodified even when ring A is oxidized. It does not considerably change the thermodynamics ofring A but strongly increases the rigidity of the molecule that remains planar under the neutral, anionic, orradical forms. Oxidation potentials of the phenolates range between 0.1 and 0.2 V versus a saturated calomelelectrode, which correspond to species that are very easy to oxidize and lead to the rapid formation of nonradicalspecies, underlining the potential antioxidant properties of these molecules.
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