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Issue 16, 2004
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Solid state NMR studies and density functional theory (DFT) calculations of conformers of quercetin

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Abstract

This work presents the first comparative analysis of two crystallographic modifications of quercetin (3,3′,4′,5,7-penta-hydroxyflavone). The existence of dihydrate and unhydrated forms of quercetin in the solid state is confirmed by several experimental techniques e.g. X-ray diffraction of powders, DSC, TGA, and NMR. Our studies allow an understanding of the complexity of quercetin samples obtained from different sources. A PASS-2D experiment is employed to establish principal values of 13C chemical shift tensors for both modifications. Solid state NMR spectroscopy and DFT GIAO calculations provide unique information about NMR shielding and electron density distribution for different conformers. It has been concluded that changes of conformation and hydrogen bonding pattern have great influence on bond order parameters of quercetin. Theoretical calculations and experimental data do not exclude the existence of the syn conformer of quercetin, which so far was not considered in the condensed phase.

Graphical abstract: Solid state NMR studies and density functional theory (DFT) calculations of conformers of quercetin

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Publication details

The article was received on 07 May 2004, accepted on 17 Jun 2004 and first published on 27 Jul 2004


Article type: Paper
DOI: 10.1039/B406861K
Citation: Org. Biomol. Chem., 2004,2, 2315-2322
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    Solid state NMR studies and density functional theory (DFT) calculations of conformers of quercetin

    S. Olejniczak and M. J. Potrzebowski, Org. Biomol. Chem., 2004, 2, 2315
    DOI: 10.1039/B406861K

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