scholarly journals Electrochemical and Mechanistic Study of Oxidative Degradation of Favipiravir by Electrogenerated Superoxide through Proton-Coupled Electron Transfer

ACS Omega ◽  
2021 ◽  
Author(s):  
Tatsushi Nakayama ◽  
Ryo Honda
Keyword(s):  
Electron Transfer ◽  
Oxidative Degradation ◽  
Mechanistic Study ◽  
Proton Coupled Electron Transfer

Update 1 of: Electrochemical Approach to the Mechanistic Study of Proton-Coupled Electron Transfer

2010 ◽  
Vol 110 (12) ◽  
pp. PR1-PR40 ◽  
Author(s):  
Cyrille Costentin ◽  
Marc Robert ◽  
Jean-Michel Savéant
Keyword(s):  
Electron Transfer ◽  
Mechanistic Study ◽  
Proton Coupled Electron Transfer ◽  
Electrochemical Approach

Mechanistic study of a manganese porphyrin catalyst for on-demand production of chlorine dioxide in water

2015 ◽  
Vol 19 (01-03) ◽  
pp. 492-499 ◽  
Author(s):  
Scott D. Hicks ◽  
Silei Xiong ◽  
Curt J. Bougher ◽  
Grigori A. Medvedev ◽  
James Caruthers ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Chlorine Dioxide ◽  
Transfer Reaction ◽  
Water Soluble ◽  
Reaction Pathways ◽  
Mechanistic Study ◽  
Manganese Porphyrin ◽  
Oxygen Atom Transfer ◽  
On Demand ◽  
Proton Coupled Electron Transfer

A water-soluble manganese porphyrin complex was examined for the catalytic formation of chlorine dioxide from chlorite under ambient temperature at pH 5.00 and 6.90. Quantitative kinetic modeling allowed for the deduction of a mechanism that accounts for all experimental observations. Catalysis is initiated via an OAT (Oxygen Atom Transfer) reaction resulting in formation of a putative manganese(V) oxo species, which undergoes ET (Electron Transfer) with chlorite to form chlorine dioxide. As chlorine dioxide accumulates in solution, chlorite consumption slows down and ClO 2 reaches a maximum as the system reaches equilibrium. In phosphate buffer at pH 6.90, manganese(IV) oxo accumulates and its reaction with ClO 2 gives ClO 3-. However, at pH 5.00 acetate buffer proton coupled electron transfer (PCET) from chlorite to manganese(IV) oxo is fast and irreversible leading to chlorate formation only via the putative manganese(V) oxo species. These differences underscore how PCET rates affect reaction pathways and mechanism. The ClO 2 product can be collected from the aqueous reaction mixture via purging with an inert gas, allowing for the preparation of chlorine dioxide on-demand.

scholarly journals Mechanistic Study on Catalytic Disproportionation of Hydrazine by a Protic Pincer-Type Iron Complex through Proton-Coupled Electron Transfer

2019 ◽  
Vol 2020 (15-16) ◽  
pp. 1472-1482
Author(s):  
Hiromasa Tanaka ◽  
Seiji Hitaoka ◽  
Kazuki Umehara ◽  
Kazunari Yoshizawa ◽  
Shigeki Kuwata
Keyword(s):  
Electron Transfer ◽  
Iron Complex ◽  
Mechanistic Study ◽  
Proton Coupled Electron Transfer

scholarly journals Electrochemical and Mechanistic Study of Structure–Activity Relationship of α-, β-, γ-, and δ-Tocopherol on Superoxide Elimination in N,N-Dimethylformamide through Proton-Coupled Electron Transfer

2021 ◽  
Author(s):  
Tatsushi Nakayama ◽  
Ryo Honda ◽  
Kazuo Kuwata ◽  
Shigeyuki Usui ◽  
Bunji Uno
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Methyl Group ◽  
Superoxide Radical Anion ◽  
Proton Coupled Electron Transfer ◽  
Spin Resonance ◽  
Relationship Of

Abstract: Elimination of superoxide radical anion (O2•−) by tocopherols (TOH), and related compounds was investigated on the basis of cyclic voltammetry and in situ electrolytic electron spin resonance spectral measurements in N,N-dimethylformamide (DMF) with the aid of density functional theory (DFT) calculations. Quasi-reversible O2/O2•− redox was modified by the presence of TOHs, suggesting that the electrogenerated O2•− was eliminated by α-, β-, γ-TOH through proton-coupled electron transfer (PCET), but not by δ-TOH. The structure–activity correlation of α-, β-, γ-, and δ-TOH characterized by methyl group on the 6-chromanol ring was experimentally confirmed, where the methyl group promotes the PCET mechanism. Furthermore, comparative analyses using some related chemical analogues suggested that methoxyl group of the 6-chromanol ring is required for a successful electron transfer (ET) to O2•− through the PCET. The electrochemical and DFT results in dehydrated DMF suggested that the PCET mechanism involves preceding proton transfer (PT) forming hydroperoxyl radical followed by a concerted PCET (ET–PT). The O2•− elimination by TOH proceeds efficiently along the net PCET mechanism involving one ET and two PTs.

scholarly journals Electrochemical and Mechanistic Study of Reactivities of α-, β-, γ-, and δ-Tocopherol toward Electrogenerated Superoxide in N,N-Dimethylformamide through Proton-Coupled Electron Transfer

Antioxidants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Tatsushi Nakayama ◽  
Ryo Honda ◽  
Kazuo Kuwata ◽  
Shigeyuki Usui ◽  
Bunji Uno
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Methyl Group ◽  
Superoxide Radical Anion ◽  
Proton Coupled Electron Transfer ◽  
Spin Resonance ◽  
Related Compounds

Scavenging of superoxide radical anion (O2•−) by tocopherols (TOH) and related compounds was investigated on the basis of cyclic voltammetry and in situ electrolytic electron spin resonance spectrum in N,N-dimethylformamide (DMF) with the aid of density functional theory (DFT) calculations. Quasi-reversible dioxygen/O2•− redox was modified by the presence of TOH, suggesting that the electrogenerated O2•− was scavenged by α-, β-, γ-TOH through proton-coupled electron transfer (PCET), but not by δ-TOH. The reactivities of α-, β-, γ-, and δ-TOH toward O2•− characterized by the methyl group on the 6-chromanol ring was experimentally confirmed, where the methyl group promotes the PCET mechanism. Furthermore, comparative analyses using some related compounds suggested that the para-oxygen-atom in the 6-chromanol ring is required for a successful electron transfer (ET) to O2•− through the PCET. The electrochemical and DFT results in dehydrated DMF suggested that the PCET mechanism involves the preceding proton transfer (PT) forming a hydroperoxyl radical, followed by a PCET (intermolecular ET–PT). The O2•− scavenging by TOH proceeds efficiently along the PCET mechanism involving one ET and two PTs.

scholarly journals Electrochemical and Mechanistic Study of Superoxide Elimination by Mesalazine through Proton-Coupled Electron Transfer

2021 ◽  
Vol 14 (2) ◽  
pp. 120
Author(s):  
Tatsushi Nakayama ◽  
Ryo Honda
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Mechanistic Study ◽  
Hydroxybenzoic Acid ◽  
Radical Product ◽  
Functional Theory ◽  
Proton Coupled Electron Transfer ◽  
Proton Transfers ◽  
Spin Resonance ◽  
Ulcerative Colitis Treatment

The elimination of superoxide radical anions (O2•−) by 5-amino-2-hydroxybenzoic acid (mesalazine, 5-ASA), 4-amino-2-hydroxybenzoic acid (4-ASA), and related compounds used for ulcerative colitis treatment was investigated using cyclic voltammetry and electron spin resonance (ESR) analyses aided by density functional theory (DFT) calculations. Quasi-reversible O2/O2•− redox was found to be modified by the compounds, suggesting that an acid–base reaction in which a hydroperoxyl radical (HO2•) is formed from O2•− occurs. However, the deprotonated 5-ASA anion can eliminate O2•− through proton-coupled electron transfer (PCET), forming a radical product. This electron transfer (ET) was confirmed by ESR analysis. The 4-aminophenol moiety in 5-ASA plays an important role in the PCET, involving two proton transfers and one ET based on π-conjugation. The electrochemical and DFT results indicated that O2•− elimination by 5-ASA proceeds efficiently through the PCET mechanism after deprotonation of the 1-carboxyl group. Thus, 5-ASA may act as an anti-inflammatory agent in the alkali intestine through PCET-based O2•− elimination.

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