X-ray Crystallographic, Scanning Microprobe X-ray Diffraction, and Cross-Polarized/Magic Angle Spinning [superscript 13]C NMR Studies of the Structure of Cellulose III[subscript II]
The X-ray crystallographic structure of cellulose III{sub II} is characterized by disorder; the unit cell (space group P2{sub 1}; a = 4.45 {angstrom}, b = 7.64 {angstrom}, c = 10.36 {angstrom}, {alpha} = {beta} = 90{sup o}, {gamma} = 106.96{sup o}) is occupied by one chain that is the average of statistically disordered antiparallel chains. {sup 13}C CP/MAS NMR studies reveal the presence of three distinct molecular conformations that can be interpreted as a mixture of two different crystal forms, one equivalent to cellulose III{sub I}, and another with two independent glucosyl conformations in the asymmetric unit. Both X-ray crystallographic and {sup 13}C NMR spectroscopic results are consistent with an aggregated microdomain structure for cellulose III{sub II}. This structure can be generated from a new crystal form (space group P2{sub 1}; a = 4.45 {angstrom}, b = 14.64 {angstrom}, c = 10.36 {angstrom}, {alpha} = {beta} = 90{sup o}, {gamma} = 90.05{sup o}; two crystallographically independent and antiparallel chains; gt hydroxymethyl groups) by multiple dislocation defects. These defects produce microdomains of the new crystal form and cellulose III{sub I} that scanning microprobe diffraction studies show are distributed consistently through the cellulose III{sub II} fiber.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1005472
- Journal Information:
- Biomacromolecules, Vol. 10, Issue (2) ; 2009
- Country of Publication:
- United States
- Language:
- ENGLISH
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