In methanol/water, dppho bleaching (519 nm) by quercetin, QH2, exhibits biphasic kinetics. The dppho reacts completely with the quercetin anion within 100 ms. Subsequent slower bleaching involves solvent and QH2 addition to quinoid products. The fast reaction is first-order in dppho but only ca. 0.38 order in [QH2]. This extraordinary nonintegral order is attributed to reversible formation of ?-stacked {QH-/dppho} complexes in which electron transfer to products, {QHo/dpph-}, is slow (kET ? 10^5 s^-1).
Kinetics of the Oxidation of Quercetin by 2,2-Diphenyl-1-picrylhydrazyl (dpph )
2011
Abstract
In methanol/water, dppho bleaching (519 nm) by quercetin, QH2, exhibits biphasic kinetics. The dppho reacts completely with the quercetin anion within 100 ms. Subsequent slower bleaching involves solvent and QH2 addition to quinoid products. The fast reaction is first-order in dppho but only ca. 0.38 order in [QH2]. This extraordinary nonintegral order is attributed to reversible formation of ?-stacked {QH-/dppho} complexes in which electron transfer to products, {QHo/dpph-}, is slow (kET ? 10^5 s^-1).File in questo prodotto:
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