Electrophilic aromatic substitution and single-electron transfer (SET) by the phenylium ion in the gas phase: characterization of a long-lived SET intermediate

2009 ◽  
Vol 44 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Shengjun Yao ◽  
Xiang Zhang ◽  
Jing Zhou ◽  
Rong Qian ◽  
Zhe Xu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Single Electron ◽  
Electrophilic Aromatic Substitution ◽  
Single Electron Transfer ◽  
Aromatic Substitution ◽  
Phase Characterization

scholarly journals Gas-phase electrophilic aromatic substitution mechanism with strong electrophiles explained by ab initio non-adiabatic dynamics

2014 ◽  
Vol 16 (35) ◽  
pp. 18686-18689 ◽  
Author(s):  
Daniel Kinzel ◽  
Shmuel Zilberg ◽  
Leticia González
Keyword(s):  
Electron Transfer ◽  
Ab Initio ◽  
Gas Phase ◽  
Radical Pair ◽  
Electrophilic Aromatic Substitution ◽  
Single Electron Transfer ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Substitution Mechanism ◽  
Adiabatic Dynamics

Ultrafast single electron transfer producing a radical pair governs the formation of a σ-complex in gas-phase electrophilic aromatic substitution reactions.

scholarly journals Computational Characterization of Single-Electron Transfer Steps in Water Oxidation

Inorganics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 32 ◽  
Author(s):  
Adiran de Aguirre ◽  
Ignacio Funes-Ardoiz ◽  
Feliu Maseras
Keyword(s):  
Electron Transfer ◽  
Water Oxidation ◽  
Density Functional ◽  
Outer Sphere ◽  
Oxidation Catalysis ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Inner Sphere ◽  
Water Oxidation Catalysis

The presence of single-electron transfer (SET) steps in water oxidation processes catalyzed by first-row transition metal complexes has been recently recognized, but the computational characterization of this type of process is not trivial. We report a systematic theoretical study based on density functional theory (DFT) calculations on the reactivity of a specific copper complex active in water oxidation that reacts through two consecutive single-electron transfers. Both inner-sphere (through transition state location) and outer-sphere (through Marcus theory) mechanisms are analyzed. The first electron transfer is found to operate through outer-sphere, and the second one through inner-sphere. The current work proposes a scheme for the systematic study of single-electron transfer in water oxidation catalysis and beyond.

Electrochemical and in situ spectroelectrochemical behavior of 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H2OHTTAP) and [Zn(II)OHTTAP]

2001 ◽  
Vol 05 (06) ◽  
pp. 523-527 ◽  
Author(s):  
YANXIU ZHOU ◽  
ZHENXING WANG ◽  
DAIKE WANG ◽  
KENICHI SUGIURA ◽  
YOSHITERU SAKATA
Keyword(s):  
Electron Transfer ◽  
Differential Pulse ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Free Base ◽  
Cation Radicals ◽  
Pulse Voltammetry ◽  
Electron Reduction

The characterization of free base porphyrin 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H2OHTTAP) and its zinc(II) complexes [ Zn (II)OHTTAP] containing eight thioether groups at the β-pyrrole positions of the macrocycle was reported. Results obtained by cyclic voltammetry and differential pulse voltammetry indicated a five-electron reduction in five steps for each complex. They were oxidized in two single-electron-transfer steps to yield π-cation radicals and dications and reduced in three single-electron-transfer steps to yield π-anion radicals, dianions and trianions, respectively. The redox property of H2OHTTAP was unusual as compared to porphyrins (PPs) and phthalocyanines (Pcs). Each process was monitored by in situ thin-layer spectroelectrochemistry, which indicated that only the ligand was electroactive. The existence of the eight hexylthio groups was responsible for the intrastack interactions and enhanced intracolumnar and intercolumnar electron motions, resulting in improved conductivity.

scholarly journals A DFT Analysis on Antioxidant and Antiradical Activities from Anthraquinones Isolated from the Cameroonian Flora

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Judith Caroline Ngo Nyobe ◽  
Laurent Gael Eyia Andiga ◽  
Désiré Bikele Mama ◽  
Baruch Ateba Amana ◽  
Joseph Zobo Mfomo ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Electron Transfer ◽  
Vitamin C ◽  
Gallic Acid ◽  
Gas Phase ◽  
Biological Activities ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Electron Transfer Mechanism ◽  
Molecular Library

The present work is devoted to the exploration antioxidant and antiradical activity of twenty anthraquinones isolated from the Cameroonian flora at B3LYP/6-311++G(d,p) level of theory using the B3LYP/6-31 + G(d,p) geometrical data as geometry optimization starting points. The single electron transfer mechanism has been adopted to examine both biological activities. The classification of the antiradical profile to integrate the electrodonating power (ω−), electroaccepting power (ω+), donor index (Rd) and acceptor index (Ra) has been performed using the donor-acceptor map (DAM). The antioxidant and radical powers of compounds analyzed have been compared to that of two classical vitamins (vitamin C and gallic acid). The stability of each anthraquinone derivative of the molecular library has been developed according to thermodynamic and kinetic concepts. The global reactivity descriptors (GRDs; electrophilicity index (ω), electronegativity (χ), global softness (S), and global hardness (η)) have been used to analyze the reactivity. The topological analysis of optimized structures indicates that the strength of the hydrogen bonds formed is situated between 44.205 and 52.001 kJ/mol. Our B3LYP results reveal that 3-methoxy-1-vismiaquinone (in a configuration without hydrogen bond) exhibits the best antioxidant capacity in gas phase. A comparison between antioxidant performance of molecules examined and that of classical vitamins (gallic acid, caffeic acid, ferulic acid, and ascorbic acid (vitamin C)) displayed the fact that the single electron transfer (SET) mechanism is more prominent for compounds of the molecular library analyzed. In the same vein, the antiradical behaviors of anthraquinone derivatives have shown to be higher than that of gallic acid and vitamin C in gas phase and water. The 5,8-dihydroxy-2-methylantraquinone structure in a configuration bearing one hydrogen bond has been found to be the best antiradical of the series in aqueous solution.

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