In Situ Spectra of Intermediate Species Recorded during Electrochemical Reduction of p‐Benzoquinone

Pyun, Chong-Hong; Park, Su‐Moon

doi:10.1149/1.2113592

Cited by 16 publications

(7 citation statements)

References 1 publication

(1 reference statement)

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“…Further, we were able to record in situ spectra of the following intermediate species, i.e., BQH• and BQH", employing our spectrometer. The details of these observations and chemistries involved in BQ reduction are reported elsewhere (32) reduced chemically (33,34), photochemically (35)(36)(37), or electrochemically (38)(39)(40)(41)(42). When MV is electrochemically reduced, two reversible reduction reactions are observed MV2+ + e-= MV+-…”

Section: Resultsmentioning

confidence: 99%

Construction of a microcomputer controlled near normal incidence reflectance spectroelectrochemical system and its performance evaluation

Pyun¹,

Park²

1986

Anal. Chem.

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bration gave y = 1.21 and Ts = 3.7%.Although some space on the photoplate is required for recording the germanium exposures, it is compensated by the provision of suitable plate calibration data, irrespective of the composition of the sample. A possible disadvantage is that, using Ge2+, the y and T6 values obtained specify the calibration over a narrow region of the mass range. However, in practice, it is rarely possible to obtain adequate calibration data over the entire mass range using internal elements. The inconvenience of having to include separate germanium exposures on each plate is partly overcome by first recording, in turn, the exposures on each photoplate located in the plate storage chamber. When a sample is run, the plate has already recorded on it the required calibration data. No memory effects for Ge occur.Registry No. Ge2+,

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Section: Resultsmentioning

confidence: 99%

Construction of a microcomputer controlled near normal incidence reflectance spectroelectrochemical system and its performance evaluation

Pyun¹,

Park²

1986

Anal. Chem.

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“…The validity of such measurements to obtain absorbance spectra of thin/thick surface films has been presented by Hansen (18). We have recently applied the technique to in situ studies of electrogenerated solution species (17,19) as well.…”

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confidence: 99%

In Situ Spectroelectrochemical Studies on Anodic Oxidation of Copper in Alkaline Solution

Pyun

Park

1986

J. Electrochem. Soc.

142

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Spectroelectrochemical studies have been perfomed on anodic oxidation of copper in 0.10MKOH using a near normal incidence reflectance spectroelectrochemical (NNMRS) technique, and the results are reported. The results indicate that the anodic oxidation product film formed on the electrode surface can be identified and that their chemical transformations can be followed by recording spectra in situ. It is shown by this technique that hydroxides of Cu(I) and Cu(II) are first formed by anodic oxidation at corresponding potentials, and they transform to oxides upon aging.

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“…This leads to a conclusion that the band at 436 nm results from the first reduction product, i.e., anion radicals of p -BQ units. We thus assign the band at 436 nm to the anion radical, that at 775 nm to the free radical generated by protonation of the anion radical, i.e., QH • , and that at 550 nm to QH - from the similarity of their wavelengths to those observed during electrolysis of p -BQ in DMSO in the presence and absence of water. , However, the band at 389 nm has not been reported in the literature, which we assign to the dianion, Q 2- , because it is observed only below −1.0 V. Here the QH • band shows up after the dianion is generated because of the slow kinetics of the protonation reaction of Q -• due to the trace amounts of protons available in the CH 3 CN solution. The species QH - would most likely be produced by protonation of Q 2- as well.…”

Section: Resultsmentioning

confidence: 81%

“…From the results described thus far, the electrochemistry of CQ in dry CH 3 CN can be regarded as an extension of that of p -BQ as can be seen from results shown in Figures and , whereas its electrochemistry in the presence of water is entirely different from that of p -BQ in aqueous media. p -BQ undergoes a reversible one-electron transfer to form an anion radical upon reduction in nonaqueous media containing a large amount of water and even in unbuffered aqueous solutions above pH 2.5. , Its electrochemistry in buffered aqueous media or in unbuffered solutions of pH lower than 2.5 is described as a chemically reversible, but electrochemically irreversible, two electron reaction according to reaction 5, ,, which is the basis for the so-called quinone electrode used for pH measurements. No intermediate species has been detected for reaction 5 on an electrochemical time scale including CV and/or chronoamperometry.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Study on Electrochemical Reduction of Calix[4]quinone in Acetonitrile Containing Water

et al. 2004

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The mechanism of electrochemical reduction of calix[4]quinones (CQs) is of vital importance, as their reduction products, calix[4]hydroquinones (CQH8s), are known to self-assemble organic nanotubes, which in turn self-assemble novel metal nanostructures by a self-synthetic process of electrochemical reduction of solvated metals. We therefore conducted detailed studies of electrochemical reduction of CQ in rigorously dried acetonitrile (CH3CN) and in CH3CN containing varied amounts of water as well as perchloric acid. CQ undergoes a series of reversible one electron reductions in dry CH3CN leading to anion radicals of each of p-benzoquinone units followed by formation of dianions. However, a series of following chemical-electrochemical reactions with protons takes place after the initial electron transfer in CH3CN containing water. The final product of this series of reactions is identified as CQH8 via an eight electron, eight proton reaction. The intermediate species are identified, and the reaction mechanism is elucidated using transient electrochemical, electrochemical quartz crystal microbalance and spectroelectrochemical measurements. The present results could be utilized to fine control the self-assembling reaction of nanotubes by electrochemical processes and to design electrochemically controllable nanomechanical devices.

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In Situ Spectra of Intermediate Species Recorded during Electrochemical Reduction of p‐Benzoquinone

Abstract: not Available.

Cited by 16 publications

References 1 publication

Construction of a microcomputer controlled near normal incidence reflectance spectroelectrochemical system and its performance evaluation

Construction of a microcomputer controlled near normal incidence reflectance spectroelectrochemical system and its performance evaluation

In Situ Spectroelectrochemical Studies on Anodic Oxidation of Copper in Alkaline Solution

Mechanistic Study on Electrochemical Reduction of Calix[4]quinone in Acetonitrile Containing Water

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