Oxidation of N,N,N′,N′-tetraalkyl-para-phenylenediamines in a series of room temperature ionic liquids incorporating the bis(trifluoromethylsulfonyl)imide anion

Evans, Russell G.; Klymenko, Oleksiy V.; Hardacre, Christopher; Seddon, Kenneth R.; Compton, Richard G.

doi:10.1016/s0022-0728(03)00343-7

Cited by 127 publications

(116 citation statements)

References 40 publications

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“…[2,9] it is otherwise consistent with that reported in traditional nonaqueous solvents. [7] Having located the oxidation potential of TEMPO in the ionic liquid, potential-step chronoamperometry was then performed by applying an initial potential corresponding to the passage of no Faradaic current then instantaneously stepping it to a value on the plateau of the voltammetric wave and recording the current response for 10 s. This procedure was repeated at 10 K intervals over the temperature range 293-348 K. The experimental transients were fitted to the Shoup and Szabo analytical expression for chronoamperometry at a disk electrode.…”

Section: Resultssupporting

confidence: 88%

An Electrochemical and ESR Spectroscopic Study on the Molecular Dynamics of TEMPO in Room Temperature Ionic Liquid Solvents

et al. 2005

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The field of room temperature ionic liquid (RTIL) research is currently very active, with the potential of fashioning "greener" alternatives to traditional molecular solvents driving intensive studies into their applications across many chemical disciplines, which include the synthetic and electrochemical industries. [1,2] Characterisation of the transport properties and solvating ability of this new class of reaction media will presumably form an important part in realising this endeavour to its full potential, although to date, reports on more fundamental investigations of this nature have been less common. To aid in this effort, we recently explored the temperature dependence of the translational diffusion of probe molecules N,N,N',N'-tetramethyl-para-phenylenediamine, its radical cation and dication in several RTIL solvents, by means of a chronoamperometric technique. [3] Amongst these species, the variation in translational diffusion coefficient, D T , with temperature in each ionic liquid was found to obey an Arrhenius relation of general form [Eq. (1)]:where E a represents the activation energy associated with the temperature-dependent process, f 0 is a constant of proportionality and, in the current context, f = 1/D T . Furthermore, the diffusional activation energies calculated by plotting ln f versus 1/T and measuring the slope were, for a given RTIL, largely independent of solute charge or size. Subjecting the measured viscosity, h, of the ionic liquids at each temperature to the same Arrhenius-type analysis [with f = h in Equation (1)] systematically yielded an activation energy of viscous flow that also closely resembled this diffusional activation energy. This implies an inverse linear relationship between translational diffusion coefficient and solvent viscosity, akin to that commonly observed in conventional molecular solvents and generally formulated in terms of the Stokes-Einstein equation [Eq. (2)]:where a is the hydrodynamic radius of the (spherical) diffusing molecule. The current report aims to build on this work by now expanding the investigation to include rotational diffusion. The equivalent hydrodynamic description of molecular rotation in a liquid is given by the Debye-Stokes-Einstein equation [Eq. (3)]:where D R and t R are termed the rotational diffusion coefficient and rotational correlation coefficient, respectively. Note that an inverse linear relationship between rotational diffusion coefficient and solvent viscosity is again predicted. For sufficiently viscous solvents, electron spin resonance (ESR) can be utilised to measure the rotational correlation coefficient of paramagnetic species via analysis of the spectral line-shapes, a technique which exploits the fact that restricted molecular tumbling of the rotational probe leads to an incomplete averaging of the ESR signal on the experimental timescale, ultimately manifesting as asymmetry in the resulting spectrum. While ESR has seldom been employed to study ionic liquids, the reports that have appeared describe the successful app...

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Section: Resultssupporting

confidence: 88%

An Electrochemical and ESR Spectroscopic Study on the Molecular Dynamics of TEMPO in Room Temperature Ionic Liquid Solvents

et al. 2005

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“…In the case of the dication, the diffusion coefficient was significantly lower in all cases, but again more exaggerated in the RTILs (R 2 = 0.32 vs. 0.51). In one of our previous reports, [7] the unsuitability of the empirical Wilke-Chang expression [24] for estimating diffusion coefficients in ionic liquid media was demonstrated. Now, use of a second recourse of the electroanalyst, namely the assumption of equal diffusion coefficients for an electrochemical reaction system has also been shown to be potentially unwise when the solvent in question is a RTIL.…”

Section: Discussionmentioning

confidence: 94%

“…This difference alone results in important consequences for the interpretation of electrochemical data, and several cautionary remarks have already appeared in the literature. [4,6,7] Other previous investigations have examined the effect on diffusion of varying the water content of the ionic liquid and, most recently, varying the concentration of the diffusing species itself. [8,9] Regarding the ratio of diffusion coefficients between reactant and electrogenerated species under these conditions, a recent Measurements on the diffusion coefficient of the neutral molecule N,N,N',N'-tetramethyl-para-phenylenediamine and the radical cation and dication generated by its one-and two-electron oxidation, respectively, are reported over the range 298-348 K in both acetonitrile and four room temperature ionic liquids (RTILs).…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Electrochemical Study of Diffusion in Room Temperature Ionic Liquid Solvents versus Acetonitrile

et al. 2005

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Measurements on the diffusion coefficient of the neutral molecule N,N,N',N'-tetramethyl-para-phenylenediamine and the radical cation and dication generated by its one- and two-electron oxidation, respectively, are reported over the range 298-348 K in both acetonitrile and four room temperature ionic liquids (RTILs). Data were collected using single and double potential step chronoamperometry at a gold disk electrode of micrometer dimension, and analysed via fitting to the appropriate analytical expression or, where necessary, to simulation. The variation of diffusion coefficient with temperature was found to occur in an Arrhenius-type manner for all combinations of solute and solvent. For a given ionic liquid, the diffusional activation energies of each species were not only closely equivalent to each other, but also to the RTIL's activation energy of viscous flow. In acetonitrile supported with 0.1 M tetrabutylammonium perchlorate, the ratio in diffusion coefficients of the radical cation and dication to the neutral molecule were calculated as 0.89 +/- 0.05 and 0.51 +/- 0.03, respectively. In contrast, amongst the ionic liquids the same ratios were determined to be on average 0.53 +/- 0.04 and 0.33 +/- 0.03. The consequences of this dissimilarity are considered in terms of the modelling of voltammetric data gathered within ionic liquid solvents.

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“…Note that (as discussed earlier) in all cases, diffusional processes are in operation. Is well known [50,51] the electrochemical process at TMPD, which is due to two one-electron oxidations (and corresponding reductions on the reverse scan), described as:…”

Section: Electrochemistry Characterizationmentioning

confidence: 99%

Imparting improvements in electrochemical sensors: evaluation of different carbon blacks that give rise to significant improvement in the performance of electroanalytical sensing platforms

Vicentini

Ravanini

Figueiredo-Filho

et al. 2015

Electrochimica Acta

125

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Imparting improvements in electrochemical sensors: evaluation of different carbon blacks that give rise to significant improvement in the performance of electroanalytical sensing platforms, Electrochimica Acta http://dx.doi.org/10.1016/j.electacta. 2014.11.204 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Graphical abstract Imparting improvements in electrochemical sensorsThree different carbon black materials have been evaluated as a potential modifier, however, only one demonstrated an improvement in the electrochemical properties. The carbon black structures were characterised with SEM, XPS and Raman spectroscopy and found to be very similar to that of amorphous graphitic materials. The modifications utilised were constructed by three different strategies (using ultrapure water, chitosan and dihexadecylphosphate). The fabricated sensors are electrochemically characterised using N,N,N',N'-tetramethyl-para-phenylenediamine and both inner-sphere and outer-sphere redox probes, namely potassium ferrocyanide(II) and hexaammineruthenium(III) chloride, in addition to the biologically relevant and electroactive analytes, dopamine (DA) and acetaminophen (AP).Comparisons are made with an edge-plane pyrolytic graphite and glassy-carbon electrode and the benefits of carbon black implemented as a modifier for sensors within electrochemistry are explored, as well as the characterisation of their electroanalytical performances. We reveal significant improvements in the electrochemical performance (excellent sensitivity, faster heterogeneous electron transfer rate (HET)) over that of a bare glassy-carbon and edge-plane pyrolytic graphite electrode and thus suggest that there are substantial advantages of using carbon black as modifier in the fabrication of electrochemical based sensors. Such work is highly important and informative for those working in the field of electroanalysis where electrochemistry can provide portable, rapid, reliable and accurate sensing protocols (bringing the laboratory into the field), with particular relevance to those searching for new electrode materials.

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Oxidation of N,N,N′,N′-tetraalkyl-para-phenylenediamines in a series of room temperature ionic liquids incorporating the bis(trifluoromethylsulfonyl)imide anion

Cited by 127 publications

References 40 publications

An Electrochemical and ESR Spectroscopic Study on the Molecular Dynamics of TEMPO in Room Temperature Ionic Liquid Solvents

An Electrochemical and ESR Spectroscopic Study on the Molecular Dynamics of TEMPO in Room Temperature Ionic Liquid Solvents

A Comparative Electrochemical Study of Diffusion in Room Temperature Ionic Liquid Solvents versus Acetonitrile

Imparting improvements in electrochemical sensors: evaluation of different carbon blacks that give rise to significant improvement in the performance of electroanalytical sensing platforms

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