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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.


Three-dimensional structure of (a) D-(+)-catechin and (b) L-(–)-epicatechinwith MM2 method.
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fig3: Three-dimensional structure of (a) D-(+)-catechin and (b) L-(–)-epicatechinwith MM2 method.

Mentions: The catalytic activity of all thecomplexes, except [Cu2(R-DABN-4Bz4)]4+,shows that the preferred coordination of the catechols is for D-(+)-catechin. This preference is probably dictated by the chirality ofthe binaphthyl or lysine residues, as shown by our studies on related complexes[24–26], and especially by the spatial disposition of the catechol substrates.In fact, by simple calculation of molecular energy minimization, D-(+)-catechin shows a disposition almost planar with only the hydroxylgroup out of plane (Figure 3(a)).


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)

Three-dimensional structure of (a) D-(+)-catechin and (b) L-(–)-epicatechinwith MM2 method.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Three-dimensional structure of (a) D-(+)-catechin and (b) L-(–)-epicatechinwith MM2 method.
Mentions: The catalytic activity of all thecomplexes, except [Cu2(R-DABN-4Bz4)]4+,shows that the preferred coordination of the catechols is for D-(+)-catechin. This preference is probably dictated by the chirality ofthe binaphthyl or lysine residues, as shown by our studies on related complexes[24–26], and especially by the spatial disposition of the catechol substrates.In fact, by simple calculation of molecular energy minimization, D-(+)-catechin shows a disposition almost planar with only the hydroxylgroup out of plane (Figure 3(a)).

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.