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231223s2004 xx ||||| 00| ||eng c |
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|a (NLM)14971019
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|a DE-627
|b ger
|c DE-627
|e rakwb
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| 041 |
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|a eng
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| 100 |
1 |
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|a Besombes, Stéphane
|e verfasserin
|4 aut
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| 245 |
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|a Conformational study of a guaiacyl beta-O-4 lignin model compound by NMR. Examination of intramolecular hydrogen bonding interactions and conformational flexibility in solution
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|c 2004
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| 336 |
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|a Text
|b txt
|2 rdacontent
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| 337 |
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|a ohne Hilfsmittel zu benutzen
|b n
|2 rdamedia
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| 338 |
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|a Band
|b nc
|2 rdacarrier
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| 500 |
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|a Date Completed 04.04.2005
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|a Date Revised 21.11.2013
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|a published: Print
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|a Citation Status MEDLINE
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| 520 |
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|a Copyright 2004 John Wiley & Sons, Ltd.
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|a Intramolecular H-bonding interactions were investigated in solution for the threo and erythro diastereomeric forms of a guaiacyl beta-O-4 lignin model compound by using the NMR data obtained from hydroxyl protons. Temperature coefficients of the chemical shifts (ddelta/dT) and coupling constants (3J(HCOH)) were measured in aprotic and protic solutions: DMSO-d6, acetone-d6 and acetone-d6-water. The NMR parameters do not support the existence of strong and persistent intramolecular H-bonds that could participate in the stabilization of the guaiacyl beta-O-4 structure in solution, but instead indicate that intermolecular H-bonds to solvent predominate. 1D NOE experiments nevertheless revealed the presence of a direct chemical exchange between the hydroxyl protons, suggesting the possible existence of weak and transient intramolecular H-bonding interactions. The conformational flexibility of the threo structure was also investigated in acetone solution from the measurement of long-range 1H, 1H and 1H, 13C coupling constants and from NOESY experiments. The NMR data are not consistent with any single conformation, indicating that different conformers co-exist in solution. The experimental results support the conformational flexibility predicted by molecular dynamics simulations performed in a previous study. Finally, both experimental and theoretical approaches indicate that weak intramolecular H-bonds can exist transiently in solution, breaking and reforming as the beta-O-4 molecule undergoes conformational interconversion, but cannot be invoked as possible means of conferring rigidity to the beta-O-4 structure
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|a Journal Article
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|a Research Support, Non-U.S. Gov't
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|a Indicators and Reagents
|2 NLM
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|a Protons
|2 NLM
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|a Hydroxyl Radical
|2 NLM
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|a 3352-57-6
|2 NLM
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| 650 |
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|a Guaifenesin
|2 NLM
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| 650 |
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|a 495W7451VQ
|2 NLM
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| 650 |
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|a guaiacylglycerol-beta-guaiacyl ether
|2 NLM
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| 650 |
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|a 7382-59-4
|2 NLM
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| 650 |
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|a Carbon
|2 NLM
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| 650 |
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|a 7440-44-0
|2 NLM
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| 700 |
1 |
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|a Utille, Jean-Pierre
|e verfasserin
|4 aut
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| 700 |
1 |
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|a Mazeau, Karim
|e verfasserin
|4 aut
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| 700 |
1 |
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|a Robert, Danielle
|e verfasserin
|4 aut
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| 700 |
1 |
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|a Taravel, François R
|e verfasserin
|4 aut
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| 773 |
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|i Enthalten in
|t Magnetic resonance in chemistry : MRC
|d 1985
|g 42(2004), 3 vom: 27. März, Seite 337-47
|w (DE-627)NLM098179667
|x 0749-1581
|7 nnns
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| 773 |
1 |
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|g volume:42
|g year:2004
|g number:3
|g day:27
|g month:03
|g pages:337-47
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|a AR
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