title: CP/MAS (13)C NMR study of cellulose and cellulose derivatives. 2. Complete assignment of the (13)C resonance for the ring carbons of cellulose triacetate polymorphs.
abstract: Complex ring (13)C resonance lines of the cross-polarization/magic angle spinning (CP/MAS) (13)C NMR spectra of cellulose triacetate (CTA) I and CTA II were completely assigned, for the first time, by (13)C-enriched CTA allomorphs. The (13)C-enriched CTA I was prepared by heterogeneous acetylation of bacterial cellulose which was biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 from culture medium containing D-(2-(13)C)-, D-(3-(13)C)-, or D-(5-(13)C)glucose as a carbon source, while CTA II samples were obtained by solution acetylation of the (13)C-enriched bacterial celluloses. From comparison of the spectra of normal CTA prepared from ramie with those of the enriched CTA samples, it was revealed that all carbons composed of CTA I appeared as a singlet, while those of CTA II except for C1 were shown as equal-intensity doublets in the CP/MAS (13)C NMR spectrum. This finding suggests that CTA I is made up of one kind of glucopyranose residue while there are two magnetically inequivalent sites in the unit cell of CTA II in the same population.
authors.affiliation: Bruker Biospin Co., Ltd., Tsukuba, Ibaraki 305-0051, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kono
authors.forename: Tomoki
authors.initials: T
authors.lastname: Erata
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Takai
mesh_terms: D000091:Acetobacter / Q000378:metabolism; D002247:Carbon Isotopes; D002482:Cellulose / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005947:Glucose / Q000378:metabolism; D007553:Isotope Labeling; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D002482:Cellulose; C024671:cellulose triacetate; D005947:Glucose