Voltammetric evaluation of the effective acidities (pKa') for Broensted acids in aprotic solvents

Barrette, William C.; Johnson, Harry W.; Sawyer, Donald T.

doi:10.1021/ac00275a030

Cited by 183 publications

(133 citation statements)

References 44 publications

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“…2B), shows that the BQ mediator gives an improved response. The difference is likely due to the lower O2 concentration (about 1 mM at 1 atm 55 ). In comparing Figs.…”

Section: Secm Assay Of Immobilized Enzyme Activitymentioning

confidence: 97%

Fabricating and Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes with Scanning Electrochemical Microscopy

Tenent

Wipf

2001

ANAL. SCI.

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The scanning electrochemical microscope (SECM) is used to image the activity of enzymes immobilized on the surfaces of disk-shaped carbon-fiber electrodes. SECM was used to map the concentration of enzymatically produced hydroquinone or hydrogen peroxide at the surface of a 33-µm diameter disk-shaped carbon-fiber electrode modified by an immobilized glucose-oxidase layer. Sub-monolayer coverage of the enzyme at the electrode surface could be detected with micrometer resolution. The SECM was also employed as a surface modification tool to produce microscopic regions of enzyme activity by using a variety of methods. One method is a gold-masking process in which microscopic gold patterns act as mask for producing patterns of chemical modification. The gold masks allow operation in both a positive or negative process for patterning enzyme activity. A second method uses the direct mode of the SECM to produce covalently attached amine groups on the carbon surface. The amine groups are anchors for attachment of glucose oxidase by use of a biotin/avidin process. The effect of non-uniform enzyme activity was investigated by using the SECM tip to temporarily damage an immobilized enzyme surface. SECM imaging can observe the spatial extent and time-course of the enzyme recovery process.

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“…2B), shows that the BQ mediator gives an improved response. The difference is likely due to the lower O2 concentration (about 1 mM at 1 atm 55 ). In comparing Figs.…”

Section: Secm Assay Of Immobilized Enzyme Activitymentioning

confidence: 97%

Fabricating and Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes with Scanning Electrochemical Microscopy

Tenent

Wipf

2001

ANAL. SCI.

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“…11 Experimental assessments of pK a often rely on proton activity given a certain medium. 12 Ironically, pK a and proton activity determinations in nonaqueous media may be directly assessed via electrochemical means. 12 From a redox scale standpoint, the generation of electrons and holes of set potential is relatively trivial.…”

Section: Aidan Q Fenwickmentioning

confidence: 99%

“…12 Ironically, pK a and proton activity determinations in nonaqueous media may be directly assessed via electrochemical means. 12 From a redox scale standpoint, the generation of electrons and holes of set potential is relatively trivial. The formal potential of a redox couple may be measured by routine voltammetry techniques, even in cases where the electron transfer is irreversible.…”

Section: Aidan Q Fenwickmentioning

confidence: 99%

Catalysis by electrons and holes: formal potential scales and preparative organic electrochemistry

et al. 2015

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The present review surveys current chemical understanding of catalysis by addition and removal of an electron. As an overarching theme of this type of catalysis, we introduce the role of redox scales in oxidation and reduction reactions as a direct analogue of pK a scales in acid/base catalysis. Each scale is helpful in determining the type of reactivity to be expected. In addition, we describe several means of generating electrons and holes via chemical reactions, plasmonic resonance, radiolytic, photochemical and electrochemical methods. We specifically draw parallels between the now well-established fields of photoredox catalysis and chemical opportunities made available by electrochemical methods. We highlight accessible potential ranges for a series of electrochemical solvents and provide a discussion on experimental design, pitfalls and some remaining challenges in preparative organic electrochemistry.

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“…The main optical and electrochemical parameters together with HOMO/LUMO energies estimated by cyclic voltammetry in 0.1 M TBAClO 4 in DMSO are collected in Table 1. a in DMSO; b Calculated from the onset of the normalized absorption spectra of the dyes; c Evaluated from the DPV oxidation and reduction peak potentials in the presence of ferrocene as an internal reference (E1/2 Fc + /Fc = 0.68 V vs. NHE) [25] and using a potential value of −4.6 eV for NHE vs. vacuum [26].…”

Section: Spectroscopic and Electrochemical Propertiesmentioning

confidence: 99%

“…Electron transfer to I3 − , relevant to dye regeneration, is in all cases, hexoergonic, with ΔG° values larger than −0.2 eV, allowing to predict favorable kinetics. a in DMSO; b Calculated from the onset of the normalized absorption spectra of the dyes; c Evaluated from the DPV oxidation and reduction peak potentials in the presence of ferrocene as an internal reference (E 1/2 Fc + /Fc = 0.68 V vs. NHE) [25] and using a potential value of´4.6 eV for NHE vs. vacuum [26].…”

Section: Spectroscopic and Electrochemical Propertiesmentioning

confidence: 99%

Molecular Level Factors Affecting the Efficiency of Organic Chromophores for p-Type Dye Sensitized Solar Cells

et al. 2016

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Abstract:A series of mono-and di-branched donor-π-acceptor charge-separated dyes incorporating triphenylamine as a donor and either Dalton's or benzothiadiazole group as strong acceptors was synthesized and its fundamental properties relevant to the sensitization of nanocrystalline NiO investigated. The dyes exhibited an intense visible absorption band with a strong charge transfer character favorable to NiO sensitization, shifting the electron density from the donor to the acceptor branches. Nevertheless, the computed exciton binding energy is circa twice that of a common literature standard (P1), suggesting a more difficult charge separation. When tested in p-type dye-sensitized solar cells the dyes successfully sensitized NiO electrodes, with photocurrent densities about half than that of the reference compound. Being recombination kinetics comparable, the larger photocurrent generated by P1 agrees with the superior charge separation capability originating by its smaller exciton binding energy.

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Voltammetric evaluation of the effective acidities (pKa') for Broensted acids in aprotic solvents

Cited by 183 publications

References 44 publications

Fabricating and Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes with Scanning Electrochemical Microscopy

Fabricating and Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes with Scanning Electrochemical Microscopy

Catalysis by electrons and holes: formal potential scales and preparative organic electrochemistry

Molecular Level Factors Affecting the Efficiency of Organic Chromophores for p-Type Dye Sensitized Solar Cells

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