Two-electron oxidation of N,N,N′,N′-tetramethylphenylenediamine with a chromium(<scp>v</scp>) salen complex

Chaka, Gezahegn; Bakač, Andreja

doi:10.1039/b811140e

Cited by 9 publications

(8 citation statements)

References 29 publications

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“…oxidation of TMB by salenCr V is expected to be faster in the absence of added [H + ], in analogy to the reaction of TMPD with (salen)Cr V O + in aqueous solution. 25 The opposite dependence on [H + ] in the present work lends additional support to our assignment of the MSN-(salen)Cr III /PhIO reaction as a rate determining step in the catalytic oxidation of TMB in acidic solutions.…”

Section: Discussionsupporting

confidence: 84%

“…In our recent work on the reaction of (salen)Cr V O + with another organic amine, tetramethylphenylene diamine (TMPD), we have unequivocally demonstrated an initial 2-e reaction followed by comproportionation with TMPD which yielded TMPD ∑ + as the ultimate product. 25 The assignment of the oxidation state to the initial product of the TMB reaction was initially thwarted by the widely disparate and sometimes conflicting spectral data 19,26-30 for the two oxidized forms, TMB ∑ + , and TMB 2+ . Part of the problem appears to lie in the similarity of the visible spectra of these two species, which has sometimes led to erroneous assignment of the reaction product.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica

et al. 2009

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A comparative study of catalytic activity under homogeneous and heterogeneous conditions was carried out using the (salen)Cr(III)-catalyzed oxidation of tetramethylbenzidine (TMB) with iodosobenzene as a model reaction. Amine-functionalized mesoporous silica nanoparticles (MSN) were synthesized in a co-condensation reaction and functionalized with salen via a covalent Si-C bond. A Cr(III) complex of this supported ligand, MSN-(salen)Cr(III), was prepared and characterized. Data from powder XRD, BET isotherms and BJH pore size distribution all showed that MSN-(salen)Cr(III) still had the typical MSN high surface area, narrow pore size distribution, and ordered hexagonal pore structure, which were further confirmed by transmission electron microscopy (TEM) images. (13)C and (29)Si solid-state NMR data provided structural information about the catalyst and verified successful functionalization of the salen ligand and coordination to Cr(III). No unreacted salen or Cr(III) were observed. The loadings of salen and salen-Cr(III) complex were determined via TGA and EDX, respectively. Both measurements indicated that approximately 0.5 mmol/g of catalyst was loaded on the surface of MSN. The oxidation of TMB with iodosobenzene using MSN-(salen)Cr(III) as a heterogeneous catalyst exhibited both similarities and differences with the analogous homogeneous reaction using (salen)Cr(III)(H(2)O)(+) as a catalyst in aqueous acetonitrile. In the presence of 0.10 M HClO(4), the two catalytic reactions proceeded at similar rates and generated the doubly oxidized product TMB(2+). In the absence of acid, the radical cation TMB (+) was produced. The kinetics of the heterogeneous reaction in the absence of added acid responded to concentrations of all three reagents, i.e. (salen)Cr(III), TMB, and PhIO.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica

et al. 2009

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“…The two peaks were observed at 0.12 V and 0.47 V vs. SCE, respectively [34,35]. The first oxidation peak (Eo_1 = 0.12 V) was also similar to the value reported by [36].…”

Section: Mfc Characterization Using Linear Sweep Voltammetry (Lsv) Ansupporting

confidence: 84%

Reaction kinetics for microbial-reduced mediator in an ethanol-fed microbial fuel cell

et al. 2019

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Microbial fuel cell (MFC) is an emerging energy production technology which converts the chemical energy stored in biologically degradable compounds to electricity at high efficiency. MFC with added mediator can enhance the electron transfer from the microbes to the anode, and used to treat industrial waste gases. In this work, the rate of microbial-reduced mediator reaction at the surface of glassy carbon (GC) electrode in an ethanol-fed MFC was investigated using cyclic voltammetry (CV), and compared with linear sweep voltammetry (LSV). The CV method provided a better estimation of the kinetic parameters than the LSV method due to low concentrations of the mediators used (0.2-1.0 mM), affecting the Tafel behaviours. All of the voltammograms indicated a quasi-reversible process for the anode reaction. The highest exchange current density (io) of 0.14±0.01 mA/cm2 and the highest power output of 0.008 mW/cm2 were obtained using 0.2 mM N′,N′,N′,N′-TMPD as the mediator. The MFC power density of 0.03 mW/cm2 was achieved for 1 mM N-TMPD. Further increase in the power density (0.16 mW/cm2) was possible with carbon cloth electrode. The results of this study confirmed the advantage of a mediator for gaseous pollutant treatment and electricity production in a MFC.

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“…When Me 2 Fc is replaced by N , N , N ′, N ′-tetramethylphenylenediamine (TMPD), however, electron transfer from TMPD to [Cu II 2 (N3)(O 2 2− )] 2+ occurred efficiently to completion as indicated by disappearance of the absorption band at 490 nm due to [Cu II 2 (N3)(O 2 2− )] 2+ , which was accompanied by appearance of the absorption band at 600 nm due to TMPD •+ [69,70]. Based on the one-electron oxidation potentials of TMPD ( E (TMPD •+ /TMPD) = 0.12 V vs. SCE) [70] and Me 2 Fc ( E (Me 2 Fc + /Me 2 Fc) = 0.26 V vs. SCE) [71,72], the oneelectron reduction potential of [Cu II 2 (N3)(O 2 2− )] 2+ is estimated to be 0.19 ± 0.07 V vs. SCE [67].…”

Section: Electron-transfer Reduction Of Cu2o2 Complexesmentioning

confidence: 99%

Kinetics and thermodynamics of formation and electron-transfer reactions of Cu–O2 and Cu2–O2 complexes

Fukuzumi

Karlin

2013

Coordination Chemistry Reviews

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The kinetics and thermodynamics of formation of Cu(II)-superoxo (Cu-O2) complexes by the reaction of Cu(I) complexes with dioxygen (O2) and the reduction of Cu(II)-superoxo complexes to dinuclear Cu-peroxo complexes are discussed. In the former case, electron transfer from a Cu(I) complex to O2 occurs concomitantly with binding of O2•− to the corresponding Cu(II) species. This is defined as an inner-sphere Cu(II) ion-coupled electron transfer process. Electron transfer from another Cu(I) complex to preformed Cu(II)-superoxo complexes also occurs concomitantly with binding of the the Cu(II)-peroxo species with the Cu(II) species to produce the dinuclear Cu-peroxo (Cu2-O2) complexes. The kinetics and thermodynamics of outer-sphere electron-transfer reduction of Cu2-O2 complexes are also been discussed in light of the Marcus theory of outer-sphere electron transfer.

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Two-electron oxidation of N,N,N′,N′-tetramethylphenylenediamine with a chromium(v) salen complex

Cited by 9 publications

References 29 publications

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica

Reaction kinetics for microbial-reduced mediator in an ethanol-fed microbial fuel cell

Kinetics and thermodynamics of formation and electron-transfer reactions of Cu–O2 and Cu2–O2 complexes

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