Moessbauer studies on hemin derivatives of .alpha.,.beta.,.gamma.,.delta.-tetraphenylporphine

Maricondi, Chris; Straub, Darel K.; Epstein, Lawrence

doi:10.1021/ja00767a017

Cited by 31 publications

(13 citation statements)

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“…The parameters of doublet 1 (δ Fe = 0.24–0.33 and Δ E Q = 0.62–0.66) are consistent in magnitude to those of the mononuclear five-coordinate chloride iron(III)porphyrinates (δ Fe = 0.24–0.44 and Δ E Q = 0.46–1.03 mm/s, Table ). − However, the parameters of doublet 2 (δ Fe = 0.15–0.26 and Δ E Q = 2.13–2.32) are close to those of the mononuclear low-spin bis-imidazole iron(III)porphyrinates (δ Fe = 0.10–0.24 and Δ E Q = 1.66–2.35 mm/s). , This is in accordance with EPR studies (Figure a) in which major high-spin [Fe(TImPP)]Cl and minor low-spin iron(III) chain and/or oligomer complexes (e.g., {[Fe(TImPP)]Cl} n and/or [Fe(TImPP)]Cl···[Fe(TImPP)(Im) 2 ] + ···[Fe(TImPP)]Cl, Im: coordination from neighboring molecules) were observed.…”

Section: Resultssupporting

confidence: 86%

Intermolecular Interactions and Intramolecular Couplings of Binuclear Porphyrin Models for Cytochrome c Oxidase

et al. 2020

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Cytochrome c oxidase (CcO) has a binuclear active site composed of a high-spin heme group and a tris-histidine-ligated copper ion (CuB). By using two different porphyrin models derived by Gunter (H2TPyPP) and us (H2TImPP), we have isolated several mono- and binuclear complexes including one carbonyl and three chloride derivatives which are determined by 100 K single-crystal X-ray. Low-temperature (4 K) EPR and multitemperature (295–25 K) Mössbauer investigations on the products not only confirmed the spin states of the two metal ions (S = 5/2 Fe3+ and S = 1/2 Cu2+) but also revealed the intermolecular interactions and intramolecular couplings which are in accordance with the crystal structural features.

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Section: Resultssupporting

confidence: 86%

Intermolecular Interactions and Intramolecular Couplings of Binuclear Porphyrin Models for Cytochrome c Oxidase

et al. 2020

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“…10b shows the Mössbauer spectrum obtained with the FeTMPPCl porphyrin. An anisotropic doublet is obtained, which is reasonably well understood and has been explained by spin-spin relaxation effects with iron present as a high-spin complex [34]. An additional chemical-structural factor has to be activated above 700 °C.…”

mentioning

confidence: 75%

Experimental and theoretical modeling of Fe-, Co-, Cu-, Mn-based electrocatalysts for oxygen reduction

Tributsch

Koslowski

Dorbandt

2008

Electrochimica Acta

100

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Abstract:Experience gained during efforts towards optimization of noble-metal-free electrocatalysts for oxygen reduction is simultaneously used to understand the chemical and morphological necessities for inducing efficient multi-electron transfer catalysis. The analysis of many preparative experimental steps between the moderately performing metal porphyrines and the highly efficient transition metal-and sulfur-containing pyrolised catalyst material contributes to the following model of the catalyst: The metals function enclosed in nitrogen or graphitic environment where they are shielded against irreversible oxidation. The metals can be exchanged but are not identical in their efficiency. Higher efficiency is achieved, when the function of a binary reaction center is warranted. The carbonization of the environment is critical and provides intercalated metal centers and attached metal complexes in graphite environment for interaction with the nitrogen-chelated partner center in the simultaneously obtained graphene layers. Three alternatives for the binary catalytic center are presented and their relevance discussed on the basis of EXAFS, RAMAN, EPR, Mössbauer and X-ray spectroscopy. A parallel is drawn with the cytochrome oxidase oxygen reduction catalysis, which is proposed to proceed according to roughly the same mechanism.

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“…The dimeric compounds contain two S = 5/2 Fe3+ ions which are antiferromagnetically coupled17•24•25 via the isotropic exchange coupling Hamiltonian36•37 Kec = -JSyS2 (2) and have states with total quantum numbers S' = 0,1,. .., 5 and eigenvalues given by…”

Section: Discussionmentioning

confidence: 99%

Moessbauer-Zeeman spectra of some octaethylporphyrinato- and tetraphenylporphinatoiron(III) complexes

Dolphin¹,

Sams²,

Tsin³

et al. 1978

J. Am. Chem. Soc.

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Moessbauer studies on hemin derivatives of .alpha.,.beta.,.gamma.,.delta.-tetraphenylporphine

Cited by 31 publications

References 1 publication

Intermolecular Interactions and Intramolecular Couplings of Binuclear Porphyrin Models for Cytochrome c Oxidase

Intermolecular Interactions and Intramolecular Couplings of Binuclear Porphyrin Models for Cytochrome c Oxidase

Experimental and theoretical modeling of Fe-, Co-, Cu-, Mn-based electrocatalysts for oxygen reduction

Moessbauer-Zeeman spectra of some octaethylporphyrinato- and tetraphenylporphinatoiron(III) complexes

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