The Complete Assignment of the 13 C Cp/Mas NMR Spectra of Native Cellulose by Using 13 C Labeled Glucose

Determination of the 13C chemical shift anisotropies of cellulose I and cellulose II

“…Hence, 12 resonances should be observed by 13 C NMR in case of the I a polymorph as well as the I b polymorph. This assignment of Atalla and Van-derHart was confirmed later by using selectively 13 C labeled cellulose (Erata et al 1997;Kono et al 2002) andsolid-state INADEQUATE NMR (Lesage et al 1999). The overlapping resonances between 70 and 80 ppm were attributed to the carbon atoms C2, C3 and C5 without further identification.…”

Current characterization methods for cellulose nanomaterials

“…Most of the chemical shifts of native cellulose have been assigned with the help of 2D-NMR experiments. 213,214 However, due to signal overlap, only C1, C4 and C6 carbon signals have been well resolved, whereas the C2, C3 and C5 carbon signals are indistinguishable. C1 carbon displays a complex shape in relation with the different crystalline phases that can be found in cellulosic compounds; signals arising from C4 and C6 split into two main contributions, crystalline (around 89 and 65 ppm, respectively) and disordered (around 85 and 62 ppm, respectively) domains.…”

Spectral assignments and anisotropy data of cellulose Iα: 13C‐NMR chemical shift data of cellulose Iα determined by INADEQUATE and RAI techniques applied to uniformly 13C‐labeled bacterial celluloses of different Gluconacetobacter xylinus strains

“…This fact, however, does not have any significant impact on the data extracted by the fitting procedure. Dipolar carbon-carbon couplings are about 7.6 kHz for bond 11,22,33 [ppm] of BC NQ-5 (1) based on the measurements of Witter et al [10] and BC AY-201 (2) determined in this work. Results were obtained using an optimized version of the RAI sequence.…”

“…[1] These conclusions were subsequently confirmed by solidstate INADEQUATE NMR. [6] Further details based on correlation spectroscopy were presented by Sakellariou et al [7] and Cadars et al, [8] and the three-dimensional cellulose structure and NMR investigations thereof were discussed by Sternberg et al [9] and Witter et al [10] The complete assignment of all carbon sites in the crystalline structure was finally possible using specifically 13 Clabeled D-glucose and D-glycerol for biosynthesis, [11,12] allowing to resolve the individual chemical shifts of C2, C3, and C5. Next, the structural assignment of all 13 C-NMR signals in the two different anhydroglucose rings were succeeded by solid-state INADEQUATE NMR of specifically prepared allomorphs I α (purified Cladophora) and I β (purified tunicate cellulose).…”