Warum hat die aktive Form der Galactose-Oxidase einen diamagnetischen Grundzustand?

Müller, Jochen; Weyhermüller, Thomas; Bill, Eckhard; Hildebrandt, Peter; Ould-Moussa, Linda; Glaser, Thorsten; Wieghardt, Karl

doi:10.1002/(sici)1521-3757(19980302)110:5<637::aid-ange637>3.0.co;2-8

Cited by 20 publications

(3 citation statements)

References 13 publications

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“…In all complexes, oxidized or not, the α angle ranges from 125 to 130 ° while the β angle is between 32 and 44 °, close to the values found in the galactose oxidase ( α =129 ° and β =75 °) and in contrast with the values of 180 and 90 ° found in copper salen complexes . Thus, from a geometrical point of view, phosphasalen complexes are better structural models for the galactose oxidase, which possesses an open‐shell singlet ground state ( S =0).…”

Section: Resultssupporting

confidence: 65%

“…Thus, from a geometrical point of view, phosphasalen complexes are better structural models for the galactose oxidase, which possesses an open‐shell singlet ground state ( S =0). The orientation of the π‐orbital of the tyrosine radical with respect to the magnetic dx 2 −y 2 orbital in the xy ‐plane of the copper, that is, the α and β angles, has been proposed to be the reason for such an electronic structure by Wieghardt and co‐workers . This is in agreement with Goodenough and Kanamori rules for singlet and triplet discrimination .…”

Section: Resultssupporting

confidence: 62%

“…This contrasts with the sp 2 hybridization of the carbon in the imine group of salen complexes, and explains why the planes of the Psalen phenoxide cannot be found in the NOON coordination plane. This geometrical distortion can be measured with both the CuOC(phenoxide) angle ( α angle), as well as the torsion angle between the plane of the phenoxide ring and the NOON coordination plane ( β angle) (Figure ) …”

Section: Resultsmentioning

confidence: 99%

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Electronic Structures of Mono‐Oxidized Copper and Nickel Phosphasalen Complexes

Marín

Cheisson

Singh-Chauhan

et al. 2017

Chemistry A European J

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Non-innocent ligands render the determination of the electronic structure in metal complexes difficult. As such, a combination of experimental techniques and quantum chemistry are required to correctly elucidate them. This paper deals with the one-electron oxidation of copper(II) and nickel(II) complexes featuring a phosphasalen ligand (Psalen), which differs from salen analogues by the presence of iminophosphorane groups (P=N) instead of imines. Various experimental techniques (X-ray diffraction, cyclic voltammetry, NMR, EPR, and UV/Vis spectroscopies, and magnetic measurements) as well as quantum chemical calculations were used to define the electronic structure of the oxidized complexes. These can be modified by a small change in the ligand structure, that is, the replacement of a tert-butyl group by a methoxy on the phenoxide ring. The different techniques have allowed quantifying the amount of spin density located on the metal center and on the Psalen ligands. All complexes were found to possess a multi-configurational ground state, in which the ratio of the +II versus +III oxidation state of the metal center, and therefore the phenolate versus phenoxyl radical ligand character, varies upon the substituents. The tert-butyl group favors a strong localization on the metal center whereas with the methoxy group the metallic configurations decrease and the ligand configurations increase. The importance of the geometrical considerations compared with the electronic substituent effect is highlighted by the differences observed between the solid-state (EPR, magnetic measurements) and solution characterizations (EPR and NMR data).

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Section: Resultssupporting

confidence: 65%

Section: Resultssupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

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Electronic Structures of Mono‐Oxidized Copper and Nickel Phosphasalen Complexes

Marín

Cheisson

Singh-Chauhan

et al. 2017

Chemistry A European J

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Vom Strukturmodell der Galactose-Oxidase zur homogenen Katalyse: effiziente aerobe Oxidation von Alkoholen

et al. 1998

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Zwei Reaktionswege katalysiert der zweikernige Kupfer(II)‐Phenoxyl‐Komplex 1 – ein funktionelles Modell des Metalloenzyms Galactose‐Oxidase – bei der Oxidation von primären und sekundären Alkoholen mit Sauerstoff (Luft) in homogener Lösung. Dabei entstehen die entsprechenden Aldehyde bzw. Ketone und/oder 1,2‐Glycole (oxidative C‐C‐Kupplung); als Reduktionsprodukt entsteht nicht Wasser, sondern H2O2.

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Was können wir von der Natur über die Reaktivität koordinierter Phenoxylradikale lernen? – Eine bioanorganische Glanzleistung

Krüger

1999

Angewandte Chemie

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Ein‐ und zweikernige Kupfer(II)‐Komplexe mit koordinierten Phenoxylgruppen (z. B. das von Wieghardt, Chaudhuri et al. kürzlich vorgestellte Komplexkation 1) ergaben hohe katalytische Aktivitäten bei der enzymähnlichen Oxidation von Alkoholen zu Aldehyden. Diese Komplexe dienen damit als hervorragende funktionale Modellkomplexe für die Galactose‐Oxidase und ermöglichen Untersuchungen zur Reaktivität der koordinierten Phenoxylradikale.

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Warum hat die aktive Form der Galactose-Oxidase einen diamagnetischen Grundzustand?

Cited by 20 publications

References 13 publications

Electronic Structures of Mono‐Oxidized Copper and Nickel Phosphasalen Complexes

Electronic Structures of Mono‐Oxidized Copper and Nickel Phosphasalen Complexes

Vom Strukturmodell der Galactose-Oxidase zur homogenen Katalyse: effiziente aerobe Oxidation von Alkoholen

Was können wir von der Natur über die Reaktivität koordinierter Phenoxylradikale lernen? – Eine bioanorganische Glanzleistung

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