Ferrocene as an internal standard for electrochemical measurements

Gagné, Robert R.; Koval, Carl A.; Lisensky, George C.

doi:10.1021/ic50211a080

Cited by 1,084 publications

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“…Ferrocene (5 Â 10 -3 M) was added to the cell after all scan rates were completed to reference the potentials to the ferrocene-ferrocenium redox couple. 28 All potentials in this work are reported with respect to this redox couple (internal standard) because the potential of the reference electrode was not perfectly constant.…”

Section: Methodsmentioning

confidence: 99%

Dications of Benzylidenefluorene and Diphenylmethylidene Fluorene: The Relationship between Magnetic and Energetic Measures of Antiaromaticity

Hatfield

Patel

et al. 2010

J. Org. Chem.

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Oxidation of m-and p-substituted benzylidene fluorenes to antiaromatic dications was attempted by electrochemical and chemical means. Electrochemical oxidation to dications was successful for benzylidene fluorenes with p-methoxy, p-methyl, p-fluoro, and unsubstituted phenyl rings in the 3-position; attempts to oxidize the m-substituted derivatives via electrochemistry were unsuccessful. Chemical oxidation with SbF 5 /SO 2 ClF gave the dication of 9-[(4-methoxyphenyl)methylene]-9H-fluorene cleanly; oxidation of all other substituted benzylidene fluorenes resulted in mixtures of products. The excellent linear relationship between the chemical shifts calculated by the GIAO method and the experimental shifts for the p-methoxy-substituted benzylidene fluorene dication suggests that the calculations satisfactorily reflect the magnetic properties of this dication and potentially those of the other dications studied. The redox potentials from electrochemical oxidation, a measure of the stability of the dications, showed a good linear relationship with another measure of stability, the calculated difference in energy between each dication and its neutral precursor. The dications of benzylidene fluorenes were less stable than the dications of diphenylmethylidene fluorenes; within each type of compound, dications with p-substituted phenyl rings were more stable than dications with m-substituted phenyl rings and dications with phenyl rings substituted with electron-donating groups were more stable than dications with phenyl rings substituted with electron-withdrawing groups. The antiaromaticity of the fluorenyl system was assessed through the nucleus-independent chemical shift (NICS) that was also calculated by the GIAO method. The plot of the NICS values per square area versus the calculated energy difference for the dications showed a moderate degree of linearity; the plot of NICS values per square area versus the oxidation potentials was less linear. Thus, a suggestive, but not conclusive, relationship between magnetic and energetic measures of antiaromaticity was observed.

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Section: Methodsmentioning

confidence: 99%

Dications of Benzylidenefluorene and Diphenylmethylidene Fluorene: The Relationship between Magnetic and Energetic Measures of Antiaromaticity

Hatfield

Patel

et al. 2010

J. Org. Chem.

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“…Ferrocene was used as an internal standard, 0.400 V vs. NHE being considered. 24 Spectroelectrochemistry was performed using an optically transparent thin-layer cell as previously described. 25 The ferrocenium/ferrocene couple was used to monitor the reference electrode.…”

Section: Materials and General Methodsmentioning

confidence: 99%

“…25 The ferrocenium/ferrocene couple was used to monitor the reference electrode. 24 Mössbauer spectra were measured at 298 K and 115 K against a 57 Co(Rh) source, operating in the constant acceleration mode. Velocity calibration was carried out through the resonance lines of metallic iron, and isomer shifts were given relative to metallic iron at room temperature.…”

Section: Materials and General Methodsmentioning

confidence: 99%

Synthesis, molecular structure and spectroscopic, electrochemical and magnetic properties of a new dinuclear iron complex containing µ-sulfate-di-µ-alkoxo bridges: evaluating the influence of the sulfate bridge on the physicochemical properties of the di-µ-alkoxo-diiron unit

Horn¹,

Vencato²,

Bortoluzzi³

et al. 2006

J. Braz. Chem. Soc.

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“…Ferrocene was used as internal standard (E 1/2 = 0.16 V versus SCE). 22 Spectroelectrochemical experiments were carried out at room temperature in acetonitrile, under argon, with TBAPF 6 (0.1 mol L -1 ) as supporting electrolyte, using an optically transparent thinlayer cell constructed according a previously reported procedure. 23 A gold minigrid and a platinum wire were used, respectively, as working and auxiliary electrodes, and a SCE was used as the reference electrode.…”

Section: Physical Measurementsmentioning

confidence: 99%

“…Potentials were applied in the range of -0.84 to -1.06 V versus Fc + /Fc and the spectra recorded from 300 to 750 nm. The Fc + /Fc couple was used separately to monitor 22 the reference electrode (E 1/2 = 0.16 V versus SCE). X-band EPR spectra were recorded on a Bruker ESP 300E spectrometer at 77 K in CH 2 Cl 2 solution.…”

Section: Physical Measurementsmentioning

confidence: 99%

EPR and semi-empirical studies as tools to assign the geometric structures of FeIII isomer models for transferrins

Scarpellini¹,

Casellato²,

Bortoluzzi³

et al. 2006

J. Braz. Chem. Soc.

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A reação entre Fe(ClO 4 ) 3 . nH 2 O e N,N'-bis[(2-hidroxibenzil)-N,N'-bis(1-metilimidazol-2-ilmetil)]etilenodiamina (H 2 bbimen) resulta na formação de dois isômeros geométricos, A e B, do cátion complexo [Fe(bbimen)] + , os quais foram isolados e caracterizados por espectroscopia na região do infravermelho e UV-visível, espectrometria de massas, medidas de condutividade molar, voltametria cíclica, espectroeletroquímica e espectroscopia de ressonância paramagnética eletrônica (RPE). A geometria de um desses isômeros foi claramente demonstrada por análise cristalográfica de raios X de monocristal. O composto cristaliza no sistema monoclínico, grupo espacial P2 1 /c, a = 14,104 (3), b = 15,626 (3), c = 13,291 (3) Å, β = 98,07 (3) o , Z = 4, R 1 = 6,35% e wR 2 = 20,57%. As propriedades eletroquímicas do cátion [Fe(bbimen)] + (-0,58 V versus NHE) são bastante similares às das transferrinas (-0,52 V versus NHE), indicando que o complexo é um bom modelo para as propriedades redox daquelas metaloenzimas. A espectroscopia de RPE foi a única técnica espectroscópica capaz de diferenciar os dois isômeros isolados (A e B). Os estudos de RPE revelaram que o isômero A trata-se de um complexo de Fe III spin alto distorcido rombicamente (E/D ≅ 0,33) e apresenta um espectro caracterizado por uma linha estreita em g 1 ≅ 4,1 e outra larga em g 2 ≅ 9,0. O espectro de RPE do isômero B apresenta, além das linhas em g 1 ≅ 4,2 e em g 2 ≅ 9,0, um conjunto de linhas em g 1 ≅ 3,0, g 2 ≅ 3,6 e g 3 ≅ 5,1, que têm sido atribuídas a complexos de Fe III com simetria tendendo à axial (E/ D ≅ 0,22). Estudos teóricos empregando cálculos semi-empíricos, combinados com os dados de RPE, foram essenciais para a atribuição das estruturas geométricas dos isômeros A e B.The reaction of Fe(ClO 4 ) 3 . nH 2 O with N,N'-bis[(2-hydroxybenzyl)-N,N'-bis(1-methylimidazole-2-yl-methyl)]ethylenediamine (H 2 bbimen) affords two geometric isomers, A and B, of the complex cation [Fe(bbimen)] + , which were fully characterized by IR and UV-visible spectroscopies, ESI mass spectrometry, molar conductivity measurements, cyclic voltammetry, spectroelectrochemistry and EPR spectroscopy. The geometry of one of these isomers has been clearly demonstrated through X-ray crystallographic analysis. It crystallizes in the monoclinic system, space group P2 1 /c, a = 14.104 (3), b = 15.626 (3), c = 13.291 (3) Å, β = 98.07 (3) o , Z = 4, R 1 = 6.35% and wR 2 = 20.57%. The electrochemical properties of [Fe(bbimen)] + are quite similar to those of transferrins (-0.52 V versus NHE) and indicate that it is a good model for the redox potential of these metalloenzymes. EPR spectroscopy was the only spectroscopic technique able to differentiate the isolated isomers A and B. EPR studies revealed that isomer A is better described as a rhombically distorted (E/D ≅ 0.33) highspin Fe III complex (g 1 ≅ 4.1 with a shoulder at g 2 ≅ 9.0), while the spectrum of B has a set of lines at g 1 ≅ 3.0, g 2 ≅ 3.6 and g 3 ≅ 5.1, in addition to the line at g 1 ≅ 4.2 and a shoulder at g 2 ≅ 9.0, which h...

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Ferrocene as an internal standard for electrochemical measurements

Cited by 1,084 publications

References 0 publications

Dications of Benzylidenefluorene and Diphenylmethylidene Fluorene: The Relationship between Magnetic and Energetic Measures of Antiaromaticity

Dications of Benzylidenefluorene and Diphenylmethylidene Fluorene: The Relationship between Magnetic and Energetic Measures of Antiaromaticity

Synthesis, molecular structure and spectroscopic, electrochemical and magnetic properties of a new dinuclear iron complex containing µ-sulfate-di-µ-alkoxo bridges: evaluating the influence of the sulfate bridge on the physicochemical properties of the di-µ-alkoxo-diiron unit

EPR and semi-empirical studies as tools to assign the geometric structures of FeIII isomer models for transferrins

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