Antioxidant Activity/Capacity Measurement. 2. Hydrogen Atom Transfer (HAT)-Based, Mixed-Mode (Electron Transfer (ET)/HAT), and Lipid Peroxidation Assays

2016 ◽  
Vol 64 (5) ◽  
pp. 1028-1045 ◽  
Author(s):  
Reşat Apak ◽  
Mustafa Özyürek ◽  
Kubilay Güçlü ◽  
Esra Çapanoğlu
Keyword(s):  
Lipid Peroxidation ◽  
Antioxidant Activity ◽  
Electron Transfer ◽  
Hydrogen Atom ◽  
Mixed Mode ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Capacity Measurement

Atmospheric formation of the NO3 radical from gas-phase reaction of HNO3 acid with the NH2 radical: proton-coupled electron-transfer versus hydrogen atom transfer mechanisms

2014 ◽  
Vol 16 (36) ◽  
pp. 19437-19445 ◽  
Author(s):  
Josep M. Anglada ◽  
Santiago Olivella ◽  
Albert Solé
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Phase Reaction ◽  
Electron Transfer Mechanism ◽  
Proton Coupled Electron Transfer ◽  
No3 Radical ◽  
Transfer Mechanisms ◽  
Atmospheric Formation

The amidogen radical abstracts the hydrogen from nitric acid through a proton coupled electron transfer mechanism rather than by an hydrogen atom transfer process.

The water–boryl radical as a proton-coupled electron transfer reagent for carbon dioxide, formic acid, and formaldehyde — Theoretical approach

2013 ◽  
Vol 91 (2) ◽  
pp. 155-168
Author(s):  
Waled Tantawy ◽  
Ahmed Hashem ◽  
Nabil Yousif ◽  
Eman Flefel
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Bond ◽  
Electron Transfer ◽  
Hydrogen Atom ◽  
Transfer Process ◽  
Carbonyl Compounds ◽  
Hydrogen Atom Transfer ◽  
Transfer Reactions ◽  
Atom Transfer ◽  
Proton Coupled Electron Transfer

The thermochemistry of the hydrogen atom transfer reactions from the H2O–BX2 radical system (X = H, CH3, NH2, OH, F) to carbon dioxide, formic acid, and (or) formaldehyde, which produce hydroxyformyl, dihydroxymethyl, and hydroxymethyl radicals, respectively, were investigated theoretically at ROMP2/6–311+G(3DF,2P)//UB3LYP/6–31G(D) and UG3(MP2)-RAD levels of theory. Surprisingly, in the cases of a strong Lewis acid (X = H, CH3, F), the spin transfer process from the water–boryl radical to the carbonyl compounds was barrier-free and associated with a dramatic reduction in the B–H bond dissociation energy (BDE) relative to that of isolated water–borane complexes. Examining the coordinates of these reactions revealed that the entire hydrogen atom transfer process is governed by the proton-coupled electron transfer (PCET) mechanism. Hence, the elucidated mechanism has been applied in the cases of weak Lewis acids (X = NH2, OH), and the variation in the accompanied activation energy was attributed to the stereoelectronic effect interplaying in CO2 and HCOOH compared with HCHO. We ascribed the overall mechanism as a SA-induced five-center cyclic PCET, in which the proton transfers across the so-called complexation-induced hydrogen bond (CIHB) channel, while the SOMOB–LUMOC=O′ interaction is responsible for the electron migration process. Owing to previous reports that interrelate the hydrogen-bonding and the rate of proton-coupled electron-transfer reactions, we postulated that “the rate of the PCET reaction is expected to be promoted by the covalency of the hydrogen bond, and any factor that enhances this covalency could be considered an activator of the PCET process.” This postulate could be considered a good rationale for the lack of a barrier associated with the hydrogen atom transfer from the water-boryl radical system to the carbonyl compounds. Light has been shed on the water–boryl radical reagent from the thermodynamic perspective.

scholarly journals Regio- and chemoselective Csp3–H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis

2018 ◽  
Vol 9 (44) ◽  
pp. 8453-8460 ◽  
Author(s):  
Takafumi Ide ◽  
Joshua P. Barham ◽  
Masashi Fujita ◽  
Yuji Kawato ◽  
Hiromichi Egami ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Atom Transfer ◽  
Single Electron Transfer ◽  
Synergistic Catalysis

Catalyst controlled regio-, and chemo-selective C-H arylation of benzylamines.

scholarly journals COMPARATIVE ANTIRADICAL ACTIVITY AND MOLECULAR DOCKING STUDY OF BERGAPTOL AND XANTHOTOXOL

2020 ◽  
pp. 71-84
Author(s):  
Žiko Milanović ◽  
Marko Antonijević ◽  
Jelena Đorović ◽  
Dejan Milenković
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Molecular Docking ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Antiradical Activity ◽  
Docking Study ◽  
Hydrogen Atom Transfer ◽  
Molecular Docking Study ◽  
Anionic Species

The antioxidant activity of bergaptol (4-hydroxyfuro[3,2-g]chromen-7-one, BER) and xanthotoxol (9-hydroxyfuro[3,2-g]chromen-7-one, XAN) was investigated in water and benzene, as solvents. For this purpose, the density functional theory (DFT) was used. The free radical scavenging potency of investigated compounds towards different reactive oxygen species (ROS) was performed. Antioxidative mechanism of investigated compounds – hydrogen atom transfer (HAT), single-electron transfer–proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) were examined using M06-2X/6-311++G(d,p) theoretical model. The important thermodynamic parameters (BDE, IP, PDE, PA, ETE) and Gibbs free energies of reactions, were used to determine the most probable antioxidant mechanism of action. The obtained thermodynamic parameters suggested that Hydrogen Atom Transfer (HAT) is the most probable reaction pathway in benzene, while Sequential Proton Loss Electron Transfer (SPLET) was favorized in water. The obtained results indicate that the favorable mechanism of antiradical activity depends on the polarity of medium and the nature of free radical species. By comparing the antioxidant activity of investigated compounds, it can be concluded that bergaptol exhibits better antioxidant properties. Molecular docking study of neutral and anionic species of investigated compounds was performed according to Estrogen receptor alpha (ERα). In both cases, bergaptol showed better inhibitory potency. All the anionic species showed a higher inhibition constant, indicating lower inhibition potency than corresponding parent molecules.

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