One-electron oxidation of metalloporphyrins

Fuhrhop, J.‐H.; Mauzerall, D.

doi:10.1021/ja01043a027

Cited by 288 publications

(126 citation statements)

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“…However, the cyclic voltammogram reported for Ni(I1)TPP in benzonitrile/TBAP and that reported here using methylene dichloridel TBAP exhibit features which are atypical of most metalloporphyrins (22)(23)(24)(25). In the former case the cyclic voltammogram showed two overlapping suc-1 cessive one-electron oxidations which were separated I by not more than 100 mV.…”

Section: Discussionmentioning

confidence: 41%

“…4) which show that all of the bonding ITmolecular orbitals are filled. Since the n-cation radical has lost an electron from its highest filled bonding n-MO, then upon cooling an electron must move from the metal to fill the n-system and generate Ni(II1 those of previously reported Ni(II1) complexes (17,22). When the same series of epr experiments were carried out using 61Ni (I = 312) no change in the epr spectra of either the cation radical or the Ni(II1) species was observed.…”

Section: Discussionmentioning

confidence: 97%

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Electron transport via metalloporphyrins

Johnson¹,

Niem²,

Doolphin³

1978

Can. J. Chem.

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The controlled potential electrolysis of Ni(II) meso-tetraphenylporphyrin (Ni(II)TPP) gives at room temperature the corresponding metalloporphyrin π-cation radical [Ni(II)TPP]+ •. Upon freezing a solution of the π-cation radical to 77 K an internal electron transfer occurs to give [Ni(III)TPP]+. A discussion of the routes of electron transport in heme proteins is given, and the roles of metalloporphyrin π-cation radicals in electron transport is evaluated.

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Section: Discussionmentioning

confidence: 41%

Section: Discussionmentioning

confidence: 97%

Electron transport via metalloporphyrins

Johnson¹,

Niem²,

Doolphin³

1978

Can. J. Chem.

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“…These radicals are key intermediates in reactions involving porphyrins and metalloporphyrins, both in nature [6][7][8] and in the laboratory [9][10][11]. Therefore, a full knowledge of those redox processes is of great importance in the understanding of the role of the porphyrin macrocycle in the natural or artificial processes of photosynthesis, membrane electron transport or oxygenation catalysis.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins

Paliteiro

Sobral

2005

Electrochimica Acta

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A series of three meso-tetra-alkyl porphyrins (H 2 TAPs) were synthesised and their electrochemical properties were studied in dichloromethane containing either tetra-butyl ammonium perclorate (TBAP) or tetra-butyl ammonium hexafluorophosphate TBA(PF 6 ) as supporting electrolyte (SE) by cyclic voltammetry and in situ UV/vis spectroelectrochemistry. Values of E 1/2 for the recorded four redox processes of these porphyrins and of the meso-tetra-phenyl porphyrin (H 2 TPP) on glassy carbon and platinum were measured and compared. The redox data collected on the first oxidation and the first reduction processes predict that the value of (LUMO − HOMO) for the H 2 TAPs is lower than for meso-tetra-phenyl porphyrin and, therefore, that the first Q band of the electronic spectra of the H 2 TAPs is red shifted relatively to the same band in the spectrum of H 2 TPP; this shift was indeed found. The second oxidation process of the H 2 TAPs is influenced by the supporting electrolyte used and the dication then formed is consumed by an irreversible chemical reaction. The species produced in this reaction is irreversibly reduced at a considerably lower potential. The electrochemical and spectroelectrochemical data collected are consistent with the occurrence of structural distortion in the macrocycle rings of the H 2 TAPs.

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“…The product of the first redox couple led to a π-cation radical (Ni II (OEP +• ), as shown by UV-visible, EPR and resonance Raman spectroscopy. [20][21][22] (2) Scheidt and co-workers have shown that mixed valence dimers, [(Ni(OEP)2] + , can also be formed. 23,24 The mixed dimer can be reduced/oxidized at about the same potential as the Ni(OEP) oxidation couple.…”

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confidence: 99%

Spectroscopic Evidence of Nanodomains in THF/RTIL Mixtures: Spectroelectrochemical and Voltammetric Study of Nickel Porphyrins

Atifi

2015

Anal. Chem.

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The presence and effect of RTIL nanodomains in molecular solvent/RTIL mixture were investigated by studying the spectroelectrochemistry and voltammetry of nickel octaethylporphyrin (Ni(OEP)) and nickel octaethylporphinone (Ni(OEPone)). Two oxidation and 2−3 reduction redox couples were observed, and the UV−visible spectra of all stable products in THF and RTIL mixtures were obtained. The E°values for the reduction couples that were studied were linearly correlated with the Gutmann acceptor number, as well as the difference in the E°values between the first two waves (ΔE 12 °= |E 1 °− E 2 °|). The ΔE 12 °for the reduction was much more sensitive to the %RTIL in the mixture than the oxidation, indicating a strong interaction between the RTIL and the anion or dianion. The shifts in the E°values were significantly different between Ni(OEP) and Ni(OEPone). For Ni(OEP), the E 1 °values were less sensitive to the %RTIL than were observed for Ni(OEPone). Variations in the diffusion coefficients of Ni(OEP) and Ni(OEPone) as a function of %RTIL were also investigated, and the results were interpreted in terms of RTIL nanodomains. To observe the effect of solvation on the metalloporphyrin, Ni(OEPone) was chosen because it contains a carbonyl group that can be easily observed in infrared spectroelectrochemistry. It was found that the ν CO band was very sensitive to the solvent environment, and two carbonyl bands were observed for Ni(OEPone) − in mixed THF/RTIL solutions. The higher energy band was attributed to the reduced product in THF, and the lower energy band attributed to the reduced product in the RTIL nanophase. The second band could be observed with as little as 5% of the RTIL. No partitioning of Ni(OEPone) + into the RTIL nanodomain was observed. DFT calculations were carried out to characterize the product of the first reduction. These results provide strong direct evidence of the presence of nanodomains in molecular solvent/RTIL mixtures.

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One-electron oxidation of metalloporphyrins

Cited by 288 publications

References 0 publications

Electron transport via metalloporphyrins

Electron transport via metalloporphyrins

Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins

Spectroscopic Evidence of Nanodomains in THF/RTIL Mixtures: Spectroelectrochemical and Voltammetric Study of Nickel Porphyrins

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