Molecular modeling of syringyl and p-hydroxyphenyl beta-O-4 dimers. Comparative study of the computed and experimental conformational properties of lignin beta-O-4 model compounds.
As a new approach for the study of the ultrastructure of lignin, the conformational preferences of lignin beta-O-4 model compounds have been investigated by molecular modeling. The computed results have been compared with the experimental data (X-ray crystal structures and (3)J(H)(alpha)(H)(beta) NMR coupling constant values) reported in the literature. This comparison has led to an improved understanding of the influence of the structure, stereochemistry, and intramolecular H-bonding upon the conformational properties of the beta-O-4 dimers. A large number of low-energy conformations have been predicted for the structures. It has also appeared that the conformational features are predominantly governed by local steric interactions rather than by differences in the H-bonding interactions. The threo and erythro forms differ significantly in their conformational features, with a preferential extended overall shape for the threo form in which the bulky aromatic groups are distant from each other.
Besombes
Stéphane
S
Centre de Recherches sur les Macromolécules Végétales, CNRS (associated with University Joseph Fourier), BP 53, 38041 Grenoble Cedex 9, France.
Robert
Danielle
D
Utille
Jean-Pierre
JP
Taravel
François R
FR
Mazeau
Karim
K
D000840:Anisoles / Q000737:chemistry*; D002236:Carbohydrate Conformation; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D019281:Dimerization; D005960:Glucosides / Q000737:chemistry*; D005990:Glycerol / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D008031:Lignin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010666:Phenylpropionates / Q000737:chemistry*
D000840:Anisoles; D005960:Glucosides; D010666:Phenylpropionates; D008031:Lignin; C028305:syringin; D005990:Glycerol