Tyrosinase and catechol oxidase activity of copper(I) complexes supported by imidazole-based ligands: structure–reactivity correlations

Wendt, Franziska; Näther, Christian; Tuczek, Felix

doi:10.1007/s00775-016-1370-y

Cited by 29 publications

(34 citation statements)

References 69 publications

(96 reference statements)

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“…Deprotonation of L H2 ·2HCl to give the catechol L H2 is achieved with [(nBu) 4 N]OH. Compound L H2 is soluble in protic solvents like CH 3 OH, but insoluble in polar aprotics olvents such as CH 3 [26][27][28] The UV/Vis spectra of L in CH 3 OH solutions display transitions at 268, 369, and 559 nm ( Figure S3). According to DFT calculations, an isolated L H2 molecule exists in its catechol form rather than in its possible zwitterionic protomers, in which one, respectively two protons are transferred from the hydroxy groups to the imino N atomso fg uanidino groups.T he DFT calculations (B3LYP/def2-TZVPP)p redict these protomers to be 75/80 kJ mol À1 (two isomers for one protonated guanidino group) respectively 235 kJ mol À1 higher in energy ( Figure S2).…”

Section: Ligand Synthesis and Characterizationmentioning

confidence: 99%

“…logue reaction of catecholt og ive o-benzoquinone. [26][27][28] The UV/Vis spectra of L in CH 3 OH solutions display transitions at 268, 369, and 559 nm ( Figure S3). In CH 3 CN, the lowest-energetic transition (p HOMO !p* LUMO according to time-dependent DFT calculations, see MO in Supporting Information, Figure S5) is blueshifted to 539 nm, and the 372 nm (intramolecular CT p G !p* LUMO and p HOMO-2 !p* LUMO )a nd 278 nm (intramolecular CT p HOMO !p* G )t ransitions are redshifted( Figures S3, S6).…”

Section: Ligand Synthesis and Characterizationmentioning

confidence: 99%

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Homo‐ and Heterobinuclear Cu and Pd Complexes with a Bridging Redox‐Active Bisguanidino‐Substituted Dioxolene Ligand: Electronic Structure and Metal–Ligand Electron‐Transfer

Schrempp

Schneider

Kaifer

et al. 2017

Chemistry A European J

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A new redox-active 4,5-bisguanidino-substituted o-benzoquinone ligand L is synthesized, which allows rational access to heterobinuclear complexes through the sequential coordination of two metals. In the examples discussed in this work, mononuclear Cu and Pd complexes are prepared in a first coordination step, and these complexes are then used as precursors to homobinuclear [Cu -L -Cu ] and heterobinuclear [Pd -L -Cu ] complexes. In the heterobinuclear complex, the Pd is coordinated by the softer bisguanidine side of L and the Cu by the harder dioxolene side (in line with the HSAB concept). The heterobinuclear complex is in a temperature-dependent equilibrium with its dimer, with two unsymmetrical Cu-Cl-Cu bridges. The redox-chemistry of the [Cu -L-Cu ] and [Pd -L-Cu ] complexes is studied. One-electron oxidation of both complexes was found to be quasi-reversible in CV experiments, and chemical one-electron oxidation was achieved with NO (SbF ). In the case of the homobinuclear complex [L(CuCl ) ] , intramolecular ligand-metal electron-transfer, triggered by coordination of a CH CN solvent molecule, leads to a temperature-dependent equilibrium between the form [Cu -L -Cu ] at low temperatures (with CH CN coordinated to the Cu atom) and [Cu -L -Cu ] at higher temperatures (without CH CN).

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Section: Ligand Synthesis and Characterizationmentioning

confidence: 99%

Section: Ligand Synthesis and Characterizationmentioning

confidence: 99%

Homo‐ and Heterobinuclear Cu and Pd Complexes with a Bridging Redox‐Active Bisguanidino‐Substituted Dioxolene Ligand: Electronic Structure and Metal–Ligand Electron‐Transfer

Schrempp

Schneider

Kaifer

et al. 2017

Chemistry A European J

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“…[1,2] Die katalytische Oxidation von Catecholen und p-Hydrochinon mit O 2 wurde mit zweikernigen wie auch einkernigen Übergangsmetallkomplexen (vor allem Kupfer, Cobalt und Eisen) als Katalysatoren detailliert untersucht. [3][4][5][6][7] Stahl, Hammes-Schiffer et al klärten die Mechanismen solcher Reaktionen auf und gruppierten Chinone in zwei Familien:s olche mit hohen Redoxpotentialen wie 2,3-Dichlor-5,6-dicyan-1,4-benzochinon (DDQ) und bioinspirierte o-Chinone,d ie dem o-Chinon-Cofaktor ähneln, in Aminoxidasen sowie verwandten Enzymen vorkommen und niedrigere Redoxpotentiale aufweisen. [7,8] Spezielle o-Chinone ermçgli-chen die aerobe Oxidation von Aminen ohne die Notwendigkeit eines Metallkatalysators.…”

Section: Die Katalytisches Elektiveunclassified

Oxidation von organischen Substraten mit einem redoxaktiven Guanidinkatalysator

2017

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Hier wird über die ersten Beispiele fürd ie Verwendung von redoxaktiven Guanidinen als Katalysatoren bei der grünen Oxidation von organischen Substraten mit Sauerstoff berichtet. In einer Halbreaktion wird die oxidierte Form des redoxaktiven Guanidins in die reduzierte,p rotonierte Form umgewandelt, wodurche ine oxidative Dehydrierung des Substrats (3,5-Di-tert-butylcatechol!o-Benzochinon, Benzoin! Benzil und 2,4-Di-tert-butylphenol!Biphenol) stattfindet. In der anderen Halbreaktion wird eine effiziente Reoxidation des Guanidins in den oxidierten Zustand mit molekularem Sauerstoff in Gegenwart eines Kupfercokatalysators erreicht. Die Ergebnisse ebnen den Wegf üre ine breitere Verwendung von redoxaktiven Guanidinen als Oxidationskatalysatoren.

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“…[6][7][8] Recently, attention has turned to Cu(I) complexes in terms of their abilities to mimic catecholase oxidase.Ramadanet al, reported Cu(I) and Cu(II) complexes of a new tetradentate Schiff-base containing N 4 donors and found out that the Cu(I) gave the highest turnover rate. 9 Also a number of new copper(I) complexes functioning as model systems for tyrosinase have been reported [10][11][12] ,even though Cu(II) complexes still receive far greater attention in this field amongst other metal ions.…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of the Catecholase activities of a tetranuclearCu(I) complex in different Solvents

2018

IJCTR

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:The structure of [Cu 4 (μ 3 -Cl) 4 (PPh 3 ) 4 (1) reveals a four coordinate system around the metal ions and1 behaves as an effective catalyst towards the oxidation of 3,5-di-tertbutylcatechol in methanol and DMF to the corresponding quinone in the presence of oxygen. The reaction follows Michaelis-Menten enzymatic reaction kinetics with turnover numbers (Kcat), 2.06 and 1.51 h -1 in methanol and DMF respectively.

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Tyrosinase and catechol oxidase activity of copper(I) complexes supported by imidazole-based ligands: structure–reactivity correlations

Cited by 29 publications

References 69 publications

Homo‐ and Heterobinuclear Cu and Pd Complexes with a Bridging Redox‐Active Bisguanidino‐Substituted Dioxolene Ligand: Electronic Structure and Metal–Ligand Electron‐Transfer

Homo‐ and Heterobinuclear Cu and Pd Complexes with a Bridging Redox‐Active Bisguanidino‐Substituted Dioxolene Ligand: Electronic Structure and Metal–Ligand Electron‐Transfer

Oxidation von organischen Substraten mit einem redoxaktiven Guanidinkatalysator

Kinetic study of the Catecholase activities of a tetranuclearCu(I) complex in different Solvents

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