Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Song, Renming; Doan, Peter E.; Gurbiel, Ryszard J.; Sturgeon, Bradley E.; Hoffman, Brian M.

doi:10.1006/jmre.1999.1887

Cited by 9 publications

(5 citation statements)

References 18 publications

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“…However, not all N 2 ase intermediates are Kramers states, and some intermediates with S > 1 non-Kramers states with significantly large negative zero-field splittings exhibit EPR intensity at low-fields . Non-Kramers ESEEM (and ENDOR) may be collected at these low fields, providing a possible magnetic characterization technique for these unique non-Kramers systems. − In other studies, ESEEM (and ENDOR) spectroscopy excluded a possible exchangeable 14 N atom as the identity of the central light atom of FeMoco. ,,, Additionally, the observation of weak 13 C coupling by ESEEM spectroscopy has been proposed to arise from the central atom (discussed in section ). ,,, …”

Section: Spectroscopic Methodsmentioning

confidence: 99%

The Spectroscopy of Nitrogenases

et al. 2020

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Nitrogenases are responsible for biological nitrogen fixation, a crucial step in the biogeochemical nitrogen cycle. These enzymes utilize a two-component protein system and a series of iron–sulfur clusters to perform this reaction, culminating at the FeMco active site (M = Mo, V, Fe), which is capable of binding and reducing N2 to 2NH3. In this review, we summarize how different spectroscopic approaches have shed light on various aspects of these enzymes, including their structure, mechanism, alternative reactivity, and maturation. Synthetic model chemistry and theory have also played significant roles in developing our present understanding of these systems and are discussed in the context of their contributions to interpreting the nature of nitrogenases. Despite years of significant progress, there is still much to be learned from these enzymes through spectroscopic means, and we highlight where further spectroscopic investigations are needed.

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Section: Spectroscopic Methodsmentioning

confidence: 99%

The Spectroscopy of Nitrogenases

et al. 2020

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“…The estimated 14 N hyperfine parameters are as follows: | A iso ( 14 N)| = 2.4 and | A dip ( 14 N)| = 0.7 MHz. The hyperfine values are similar to those of previously reported 14 N atoms directly coordinated to the Mn(II) species. − The nuclear quadrupole parameter was estimated to be e 2 qQ / h = 4.4 MHz with η = 0, which is within the range of reported values for EDTA and other alkylamine ligands. − In addition, the 14 N ESEEM data also suggest that the simulations with two 14 N atoms are more consistent with the experimental results (Figure S15), indicating that two 14 N atoms of EDTA are bound to the Mn(II) site. This estimation is also supported by comparison of the ESEEM traces of EDTA-Mn 3 O 4 and CaEDTA-Mn 3 O 4 NPs with those of the [(EDTA)Mn] 2– complex, where the two 14 N nuclei are directly bound to the Mn(II) center, as seen in the XRD structure .…”

Section: Resultsmentioning

confidence: 99%

Probing the Structure and Binding Mode of EDTA on the Surface of Mn₃O₄ Nanoparticles for Water Oxidation by Advanced Electron Paramagnetic Resonance Spectroscopy

Kim

Park

et al. 2020

Inorg. Chem.

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Identification of the surface structure of nanoparticles is important for understanding the catalytic mechanism and improving the properties of the particles. Here, we provide a detailed description of the coordination modes of ethylenediaminetetraacetate (EDTA) on Mn 3 O 4 nanoparticles at the atomic level, as obtained by advanced electron paramagnetic resonance (EPR) spectroscopy. Binding of EDTA to Mn 3 O 4 leads to dramatic changes in the EPR spectrum, with a 5-fold increase in the axial zero-field splitting parameter of Mn(II). This indicates significant changes in the coordination environment of the Mn(II) site; hence, the binding of EDTA causes a profound change in the electronic structure of the manganese site. Furthermore, the electron spin echo envelope modulation results reveal that two 14 N atoms of EDTA are directly coordinated to the Mn site and a water molecule is coordinated to the surface of the nanoparticles. An Fourier transform infrared spectroscopy study shows that the Ca(II) ion is coordinated to the carboxylic ligands via the pseudobridging mode. The EPR spectroscopic results provide an atomic picture of surface-modified Mn 3 O 4 nanoparticles for the first time. These results can enhance our understanding of the rational design of catalysts, for example, for the water oxidation reaction.

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“…However, the high sensitivity and first-order lineshapes may make high-frequency measurements desirable. For finite NQI, the intensities reach a limiting, generally non-zero, value for low EPR frequencies because the eigenfunctions in the two electron spin manifolds become complex conjugates of each other although the eigenvalues become degenerate [21]. 9.…”

Section: General Features Of Hyscore Spectramentioning

confidence: 98%

Two-dimensional hyperfine sublevel correlation spectroscopy: Powder features for S=1/2, I=1

Maryasov¹,

Bowman²

2006

Journal of Magnetic Resonance

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Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Cited by 9 publications

References 18 publications

The Spectroscopy of Nitrogenases

The Spectroscopy of Nitrogenases

Probing the Structure and Binding Mode of EDTA on the Surface of Mn₃O₄ Nanoparticles for Water Oxidation by Advanced Electron Paramagnetic Resonance Spectroscopy

Two-dimensional hyperfine sublevel correlation spectroscopy: Powder features for S=1/2, I=1

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Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Cited by 9 publications

References 18 publications

The Spectroscopy of Nitrogenases

The Spectroscopy of Nitrogenases

Probing the Structure and Binding Mode of EDTA on the Surface of Mn3O4 Nanoparticles for Water Oxidation by Advanced Electron Paramagnetic Resonance Spectroscopy

Two-dimensional hyperfine sublevel correlation spectroscopy: Powder features for S=1/2, I=1

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Probing the Structure and Binding Mode of EDTA on the Surface of Mn₃O₄ Nanoparticles for Water Oxidation by Advanced Electron Paramagnetic Resonance Spectroscopy