Oxidation and dismutation of superoxide ion solutions to molecular oxygen. Singlet vs. triplet state

Nanni, Edward J.; Birge, Robert R.; Hubbard, Lynn M.; Morrison, Mark M.; Sawyer, Donald T.

doi:10.1021/ic50217a019

Cited by 46 publications

(34 citation statements)

References 3 publications

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“…S4b. Uncatalysed HO2 disproportionation forms in accord with previous findings a minor 1 O2 fraction, which is significantly below that from LiO2 disproportionation [28,59,60]. Equally, OHcatalysed H2O2 decomposition in the TEGDME/1000 ppm H2O is found to form minor 1 O2 in accord with previous findings in pure H2O…”

Section: Deciphering the Reaction Steps Where Catalysts Impact O2 Forsupporting

confidence: 90%

Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells

Samojlov¹,

Schuster²,

Kahr³

et al. 2020

Preprint

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Large overpotentials upon discharge and charge of Li-O2 cells have motivated extensive research into heterogeneous solid electrocatalysts or non-carbon electrodes with the aim to improve rate capability, round-trip efficiency and cycle life. These features are equally governed by parasitic reactions, which are now recognized to be caused by the highly reactive singlet oxygen (1O2). However, the link between the presence of electrocatalysts and 1O2 formation in metal-O2 cells is unknown. Here, we show that, compared to pristine carbon black electrodes, a representative selection of electrocatalysts or non-carbon electrodes (noble metal, transition metal compounds) may both slightly reduce or severely increase the 1O2 formation. The individual reaction steps, where the surfaces impact the 1O2 yield are deciphered, showing that 1O2 yield from superoxide disproportionation as well as the decomposition of trace H2O2 are sensitive to catalysts. Transition metal compounds in general are prone to increase 1O2. <br>

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Section: Deciphering the Reaction Steps Where Catalysts Impact O2 Forsupporting

confidence: 90%

Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells

Samojlov¹,

Schuster²,

Kahr³

et al. 2020

Preprint

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“…These series of reactions, the initial PT ( eq 2 ) followed by the subsequent oxidation and others, are referred to as the base-catalyzed oxidation process or the SFO. 24 , 25 The SFO is the oxidation of the substrate anion (generated by alkali O 2 •– ) by O 2 . When considering the superior kinetic expected from the CV and in situ spectral results, the mechanism will involve the sequential ET from T-705 – to HO 2 • coupled to the initial PT, that is, PCET, rather than SFO.…”

Section: Results and Discussionmentioning

confidence: 99%

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

Nakayama

Honda

2021

ACS Omega

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Electrochemical analyses aided by density functional theory calculations were used to investigate the oxidative degradation of pyrazine antiviral drugs, 3-hydroxypyrazine-2-carboxamide (T-1105) and 6-fluoro-3-hydroxypyrazine-2-carboxamide (favipiravir, T-705), by the electrogenerated superoxide radical anion (O 2 •– ). T-1105 and T-705 are antiviral RNA nucleobase analogues that selectively inhibit the RNA-dependent RNA polymerase. They are expected as a drug candidate against various viral infections, including COVID-19. The pyrazine moiety was decomposed by O 2 •– through proton-coupled electron transfer (PCET). Our results show that its active form, pyrazine-ribofuranosyl-5′-triphosphate, is easily oxidized under inflamed organs by overproduced O 2 •– through the PCET mechanism in the immune system. This mechanistic study implies that the oxidative degradation of pyrazine derivatives will be prevented by controlling the PCET through simple modification of the pyrazine structure.

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“…Singlet state dioxygen ( 1 O 2 ) is a powerful, but rather selective, oxidant of a range of biologically important molecules (Briviba et al, 1997). Formation of 1 O 2 from oxidation of

O_{2}^{- *}

is only possible with a sufficiently powerful oxidant (Koppenol, 1976), which may or may not be satisfied by different Fe(II) species (Nanni et al, 1981). …”

Section: Chemistry Of Reactions Between Superoxide and Ironmentioning

confidence: 99%

The Influence of Extracellular Superoxide on Iron Redox Chemistry and Bioavailability to Aquatic Microorganisms

Rose¹

2012

Front. Microbio.

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Superoxide, the one-electron reduced form of dioxygen, is produced in the extracellular milieu of aquatic microbes through a range of abiotic chemical processes and also by microbes themselves. Due to its ability to promote both oxidative and reductive reactions, superoxide may have a profound impact on the redox state of iron, potentially influencing iron solubility, complex speciation, and bioavailability. The interplay between iron, superoxide, and oxygen may also produce a cascade of other highly reactive transients in oxygenated natural waters. For microbes, the overall effect of reactions between superoxide and iron may be deleterious or beneficial, depending on the organism and its chemical environment. Here I critically discuss recent advances in understanding: (i) sources of extracellular superoxide in natural waters, with a particular emphasis on microbial generation; (ii) the chemistry of reactions between superoxide and iron; and (iii) the influence of these processes on iron bioavailability and microbial iron nutrition.

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Oxidation and dismutation of superoxide ion solutions to molecular oxygen. Singlet vs. triplet state

Cited by 46 publications

References 3 publications

Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells

Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells

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

The Influence of Extracellular Superoxide on Iron Redox Chemistry and Bioavailability to Aquatic Microorganisms

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