Nuances of the ECE Mechanism. I. Development of the Theoretical Relationships for Chronoamperometry<sup>1a</sup>

Hawley, M. Dale; Feldberg, Stephen W.

doi:10.1021/j100883a015

Cited by 129 publications

(48 citation statements)

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“…Chemical evidence, discussed previously, provides support for A being 6-S-cysteinyl-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid substituted with an additional cysteinyl residue. The 1 H, 13 C, HMQC, and HMBC NMR spectra, particularly the long-range 1 H-13 C connectivities obtained from HMBC spectra, are also in accord with the proposed structure for A (see Experimental). In particular, the only aromatic singlet proton resonance at 7.09 ppm (1H) exhibits connectivity to nonprotonated carbons at 144.92 ppm (C-5) and 122.52 ppm (C-8a).…”

Section: Spectroscopic Evidence For the Structures Of A-dsupporting

confidence: 77%

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Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Shen

Dryhurst

1997

Bioorganic Chemistry

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Section: Spectroscopic Evidence For the Structures Of A-dsupporting

confidence: 77%

“…The assignment of the latter carbon is supported by its connectivity to the upfield C(2)-H proton at 3.30 ppm (dd, 1H). These observations indicate that the second S-cysteinyl residue 13 C connectivity assignments based on the HMBC spectra of B support its proposed structure.…”

Section: Spectroscopic Evidence For the Structures Of A-dsupporting

confidence: 59%

Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Shen

Dryhurst

1997

Bioorganic Chemistry

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“…However, in the presence of coupled chemical reactions, the difference in peak currents between the first and second scans is a function of log k f and E 0 . [2][3][4]18,20 This is illustrated in Fig. S-2.…”

Section: Resultsmentioning

confidence: 95%

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Mann

Helfrick

Bottomley

2015

J. Electrochem. Soc.

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Theory for cyclic square wave voltammetry of an irreversible first-order chemical reaction coupling two electron transfers, i.e. an ECE mechanism, is presented. Theoretical voltammograms were calculated following systematic variation of empirical parameters to assess their impact on the shape of the voltammogram. Note that the results presented herein are applicable only to ECE processes where E 0 for the second electron transfer step is negative of that for the first. Under this condition, disproportionation reactions do not occur. From the trends obtained, diagnostic criteria for this mechanism were deduced. When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and accurately measure reaction kinetics over the range −2 ≤ log k f ≤ 6. Square wave voltammetry (SWV) has been shown to be particularly useful in identifying electrode reaction mechanisms especially those involving chemical reactions coupled to the electron transfer step.1-7 Although a strong theoretical basis exists, 8 the use of SWV for identifying electrode reaction mechanisms has been limited to a small number of electrochemists. Our goal is to broaden the use of SWV for determining electrode reaction mechanisms especially by nonexperts in electrochemistry who make occasional use of voltammetry in characterizing new compounds. Cyclic square wave voltammetry (CSWV) is a modified form of SWV that steps through the region of the formal potential of the electroactive species under study and back to the initial potential as shown in Fig. 1a. The empirical parameters that comprise the CSWV waveform are period (τ), amplitude (E sw ), increment (δE), and the potential at which the direction of the sweep is reversed (E λ ).Our current effort is focused on identifying the specific mechanisms CSWV provides a straightforward means for determining the mechanism and associated kinetic parameters. [9][10][11][12][13][14] In this work, we critically evaluate CSWV for the analysis of consecutive electron transfers coupled by a homogeneous irreversible chemical reaction, i.e. an ECE mechanism. The process used to evaluate CSWV is as follows. Theoretical voltammograms were computed by systematic variation of each empirical parameter. Figures of merit that describe the shape of the voltammogram as shown in Fig. 1b (peak potentials, peak currents, and peak widths) were compiled and correlated with the empirical parameter being varied. Trends characteristic of this mechanism were identified from these correlations and provide diagnostic criteria for assigning an electrode reaction as an ECE process. Application of these criteria will enable non-specialists to accurately assign the mechanism and, in many instances, quantify the rate constant of the chemical reaction.The ECE mechanism has been the subject of considerable interest by electrochemists over the past five decades. [2][3][4][15][16][17][18][19][20][21][22][23][24] The continuing interest reflects: (1) the challenge in mathematically modeling the...

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“…Following similar lines as for the spherical microelectrode, [41] let us consider next the possibly reversible EC r E reaction mechanism [Eqs. (13)- (15)]: [55][56][57][58] A AE e Ð B ð13Þ …”

Section: Ec R E Mechanismmentioning

confidence: 99%

A Novel Approach to the Simulation of Electrochemical Mechanisms Involving Acute Reaction Fronts at Disk and Band Microelectrodes

et al. 2012

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A new simulation algorithm is presented for describing the dynamics of diffusion reactions at the most common microelectrode 1D (planar, cylindrical, spherical) and 2D geometries (band, disk) for electrochemical mechanisms of any complexity and involving fast homogeneous reactions of any kind. A series of typical electrochemical mechanisms that create the most severe simulation difficulties is used to establish the exceptional performance and accuracy of this algorithm, which stem from the combination of (quasi)conformal transformation of space and a new method for auto-adaptive grid compression.

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Nuances of the ECE Mechanism. I. Development of the Theoretical Relationships for Chronoamperometry^1a

Cited by 129 publications

References 0 publications

Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

A Novel Approach to the Simulation of Electrochemical Mechanisms Involving Acute Reaction Fronts at Disk and Band Microelectrodes

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Nuances of the ECE Mechanism. I. Development of the Theoretical Relationships for Chronoamperometry1a

Cited by 129 publications

References 0 publications

Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Further Insights into the Oxidation Chemistry of Norepinephrine and Epinephrine in the Presence of Cysteine

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

A Novel Approach to the Simulation of Electrochemical Mechanisms Involving Acute Reaction Fronts at Disk and Band Microelectrodes

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Nuances of the ECE Mechanism. I. Development of the Theoretical Relationships for Chronoamperometry^1a