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Biomimetic modeling of copper complexes: a study of enantioselective catalytic oxidation on d-(+)-catechin and L-( - )-epicatechin with copper complexes.

Mutti FG, Pievo R, Sgobba M, Gullotti M, Santagostini L - Bioinorg Chem Appl (2008)

Bottom Line: The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones.The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower.In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Chimica Inorganica, Metallorganica e Analitica "Lamberto Malatesta", Università di Milano, Istituto ISTM-CNR, Via Venezian 21, 20133 Milano, Italy.

ABSTRACT
The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( - )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

No MeSH data available.


Proposed structures forthe putative intermediate adducts formed by the dinuclear copper(II) complexesin the catalytic oxidations of the catechins.
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sch2: Proposed structures forthe putative intermediate adducts formed by the dinuclear copper(II) complexesin the catalytic oxidations of the catechins.

Mentions: Previous studies on the catalyticoxidations of catechol derivatives demonstrated that the reaction needs thecooperation of two close copper centers [22] to enablethe binding of the catechol as a bridging ligand and allow a fast two-electrontransfer process. In the dinuclear copper complexes, the catechin substrate canonly form a productive complex by binding the catechol residue to the twocopper ions in the A sites and that forces the resting part of the molecule toapproach the optically active residue so that chiral recognition is possible(Scheme 2).


Biomimetic modeling of copper complexes: a study of enantioselective catalytic oxidation on d-(+)-catechin and L-( - )-epicatechin with copper complexes.

Mutti FG, Pievo R, Sgobba M, Gullotti M, Santagostini L - Bioinorg Chem Appl (2008)

Proposed structures forthe putative intermediate adducts formed by the dinuclear copper(II) complexesin the catalytic oxidations of the catechins.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553160&req=5

sch2: Proposed structures forthe putative intermediate adducts formed by the dinuclear copper(II) complexesin the catalytic oxidations of the catechins.
Mentions: Previous studies on the catalyticoxidations of catechol derivatives demonstrated that the reaction needs thecooperation of two close copper centers [22] to enablethe binding of the catechol as a bridging ligand and allow a fast two-electrontransfer process. In the dinuclear copper complexes, the catechin substrate canonly form a productive complex by binding the catechol residue to the twocopper ions in the A sites and that forces the resting part of the molecule toapproach the optically active residue so that chiral recognition is possible(Scheme 2).

Bottom Line: The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones.The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower.In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Chimica Inorganica, Metallorganica e Analitica "Lamberto Malatesta", Università di Milano, Istituto ISTM-CNR, Via Venezian 21, 20133 Milano, Italy.

ABSTRACT
The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( - )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

No MeSH data available.