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Cellodextrins: structure and dissolution

Project Leader
Rosenau Thomas, Project Leader
Type of Research
Basic Research
Adelwöhrer Christian, Co-worker (bis 30.11.2007)
Yoneda Yuko, Co-worker (bis 31.03.2008)
Henniges Ute, Co-worker
BOKU Research Units
Division of Chemistry of Renewable Resources
Funded by
Fonds zur Förderung der wissenschaftlichen Forschung (FWF) , Sensengasse 1, 1090 Wien, Austria
Cellulose, an essential constituent in the assembly of plant cell walls, is the most abundant natural polymer. Because of its superb nature-made properties, cellulose has found use in a large variety of applications, first of all in the pulp and paper and textile industries, but also in food stuffs, pharmaceuticals as drug-delivery systems, cosmetics, and many material-based applications. Cellulose can exist in different, largely interconvertible polymorphs (cellulose I to IV), which differ in various structural parameters, such as chain packing, H-bond pattern, orientation of the primary OH groups and ring puckering of the anhydroglucose units. Many structural parameters of the polymer cellulose are not obtained directly, but are derived from or correlated with structures of low-molecular weight model compounds (cellodextrin derivatives) that serve as short-chain cellulose fragment analogues. The elucidation of the structural properties of cellulose is fundamental to understanding its functionality in applications. Especially the processes of swelling and dissolution of cellulose, which are closely related to changes in its hydrogen bond network, are largely unknown on a molecular level, even though they are fundamental and of high industrial relevance, as for instance in the direct dissolution of cellulose in the solvent N-methylmorpholine-N-oxide (NMMO), the so-called Lyocell process.
Within this project, cellodextrin derivatives are prepared and crystallized in different polymorphs. First, a disaccharide that forms two crystal phases - analogous to the I-alpha and I-beta polymorph of native cellulose for which no pure crystals are obtainable -, and second a trisaccharide and a hydrophobically capped trisaccharide. In addition, synthetic cellulose is obtained by cationic ring-opening polymerization. Both model compounds and cellulose are synthesized in isotopically labeled form (13-C, 2-H). This allows a direct and complete signal assignment in solid-state nuclear magnetic resonance spectroscopy (NMR). For the first time, also a direct study of the hydrogen bond network by this technique becomes possible, as the hydrogen bridges are formed by detectable 1-H, while carbon-bound hydrogen signals are blinded out by deuteration, so that the results can be correlated with data from X-ray diffraction. In addition, isotopically labeled (15-N, 2-H) cellulose swelling agents and solvents (NMMO and N,N-dimethylacetamide) are synthesized. Used in combination with the labelled carbohydrate models and cellulose, the molecular interactions, especially with regard to sites of interaction and restructuring of the H-bond network, can now be followed by special solid-state NMR methods.
cellodextrins; cellulose; H-bond network; crystal structure analysis; renewable resources;

Yoneda, Y., Kawada, T., Rosenau, T., Kosma, P. (2005): Synthesis of methyl 4'-O-methyl-ß-D-cellobioside-13C12 from D-glucose-13C6.
[Japanese-European Workshop on Cellulose and Functional Polysaccharides, Wien, September 11-14]

In: Department of Chemistry, BOKU: Japanese-European Workshop on Cellulose and Functional Polysaccharides, September 11-14, Wien, 86

** Yoneda, Y; Kawada, T; Rosenau, T; Kosma, P Synthesis of methyl 4'-O-methyl-13C12-beta-D-cellobioside from 13C6-D-glucose. Part 1: reaction optimization and synthesis..

Carbohydr Res. 2005; 340(15):2428-2435 WoS PubMed FullText FullText_BOKU

** Malz, F; Yoneda, Y; Kawada, T; Mereiter, K; Kosma, P; Rosenau, T; Jäger, C Synthesis of methyl 4'-O-methyl-beta-D-cellobioside-13C12 from D-glucose-13C6. Part 2: solid-state NMR studies..

Carbohydr Res. 2007; 342(1):65-70 WoS PubMed FullText FullText_BOKU

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