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Title: | Examination of the chemical behavior of the quercetin radical cation towards some bases |
Authors: | Marković, Zoran Amic D. Milenkovic, Dejan Dimitrić Marković J. Markovic, Svetlana |
Issue Date: | 2013 |
Abstract: | It has been generally accepted that, due to high ionization potential values, single electron transfer followed by proton transfer (SET-PT) is not a plausible mechanism of antioxidant action in flavonoids. In this paper the SET-PT mechanism of quercetin (Q) was examined by revealing possible reaction paths of the once formed quercetin radical cation (Q+•) at the M0-52X/6311+G(d,p) level of theory. The deprotonation of Q+• was simulated by examining its chemical behavior in the presence of three bases: methylamine (representative of neutral bases), the MeS anion (CH 3S-) and the hydroxide anion (representative of anionic bases). It was found that Q+• will spontaneously be transformed into Q in the presence of bases whose HOMO energies are higher than the SOMO energy of Q+• in a given medium, implying that Q cannot undergo the SET-PT mechanism in such an environment. In the reaction with the MeS anion in both gaseous and aqueous phases and the hydroxide anion in the gaseous phase Q+• accepts an electron from the base, and so-formed Q undergoes the hydrogen atom transfer mechanism. On the other hand, SET-PT is a plausible mechanism of Q in the presence of bases whose HOMO energies are lower than the SOMO energy of Q+• in a given medium. In such cases Q +• spontaneously donates a proton to the base, with energetic stabilization of the system. Our investigation showed that Q conforms to the SET-PT mechanism in the presence of methylamine, in both gaseous and aqueous phases, and in the presence of the hydroxide anion, in the aqueous solution. © 2013 the Owner Societies. |
URI: | https://scidar.kg.ac.rs/handle/123456789/10313 |
Type: | article |
DOI: | 10.1039/c3cp44605k |
ISSN: | 1463-9076 |
SCOPUS: | 2-s2.0-84876913589 |
Appears in Collections: | Faculty of Science, Kragujevac Institute for Information Technologies, Kragujevac |
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