Carbon-13 NMR distinction between categories of molecular order and disorder in cellulose

Newman, Roger H.; Hemmingson, Jacqueline A.

doi:10.1007/bf00816383

Cited by 133 publications

(81 citation statements)

References 22 publications

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“…The mobility of the C-1 through C-6 atoms in cellulose can be compared via their T 1r values. The calculated values for T 1r of different cellulose signals were in good agreement with those reported [22]. From the calculated values, as shown in Tables 1 and 2, it can be concluded that the mobility of the cellulose fibers in SHW remains unaltered during the degradation process.…”

Section: Resultssupporting

confidence: 87%

“…These samples were subjected to CP-MAS NMR analysis in order to study the applicability of this technique for obtaining additional information about the material. Variable contact-time CP-MAS NMR experiments were applied to obtain structural and motional information, and to investigate the kinetics of cross polarization [19][20][21][22] of the constituting polysaccharides. In these experiments, the signal intensity depends on the contact time (t) allowed for cross polarization.…”

Section: Introductionmentioning

confidence: 99%

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CP-MAS NMR analysis of carbohydrate fractions of soybean hulls and endosperm

Fransen

Laar

Kamerling

et al. 2000

Carbohydrate Research

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CP-MAS NMR spectroscopy was used to identify soybean cellulose and pectin extracts and to investigate the kinetics of cross polarization. The in vitro incubation of cellulose and pectin, extracted from soya hull and endosperm, respectively, with sheep rumen fluid was followed with this technique. The difference in enzymatic degradability between ChSS and DASS, two pectins with identical monosaccharide composition, was explained by the degree of esterification that is lower in DASS. Variable contact time CP-MAS NMR experiments of the cellulose fraction during the incubation revealed that cellulose was degraded in a layer-by-layer way.

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Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

CP-MAS NMR analysis of carbohydrate fractions of soybean hulls and endosperm

Fransen

Laar

Kamerling

et al. 2000

Carbohydrate Research

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show abstract

“…On the other hand, Newman and Hemmingson (1995), Newman (1999) and Newman and Davidson (2004) assigned the C-4 region of the spectra without separating it into broad and narrow signals. These different interpretations of the spectra do not affect the calculation of lateral microfibril dimensions from the intensity ratio of the C-4 signal of surface and interior chains, which are agreed to lie below and above 86 ppm, respectively (Newman 1999;Larsson et al 1999), but they lead to different ideas of the level of order present in native cellulose (Vië tor et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Spatial relationships between polymers in Sitka spruce: Proton spin-diffusion studies

Altaner¹,

Apperley²,

Jarvis³

2006

Holzforschung

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The spatial arrangement of polymers in Sitka spruce (Picea sitchensis) was investigated by NMR proton spindiffusion studies, supplemented by deuterium-exchange experiments monitored by FTIR spectroscopy. The FTIR spectra of earlywood sections after vapour-phase exchange with deuterium oxide showed that 43% of the hydroxyl groups were accessible to deuteration. This value is lower than predicted in the absence of aggregation of cellulose microfibrils into larger units, but greater than the predicted level of deuteration if 3.5-nm microfibrils surrounded by hemicellulose sheaths were aggregated into 4=4 arrays without space for deuterium oxide to penetrate between the microfibrils. The rate of proton spin diffusion between lignin and cellulose was consistent with the presence of microfibril arrays with approximately these dimensions and with lignin located outside them, in both earlywood and latewood. Proton spin-diffusion data for hemicelluloses were complicated by difficulties in assigning signals to glucomannans and xylans, but there was evidence for the spatial association of one group of hemicelluloses, including acetylated glucomannans, with cellulose surfaces, while another group of hemicelluloses was in spatial proximity to lignin. These data are consistent with a number of nanoscale models for the Sitka spruce cell wall, including a model in which glucomannans are associated with microfibril surfaces within the aggregate and water can penetrate partially between these surfaces, and one in which all non-cellulosic polymers and water are excluded from the interior of each microfibril aggregate.

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“…Since the first two high-resolution solid-state NMR studies of cellulose were published in 1980 (Atalla et al 1980;Earl and VanderHart 1980), solidstate NMR spectroscopy has been an important tool in the study of the 3D architecture of PCWs. Solid-state NMR spectroscopy not only revealed the polymorphic structure of cellulose but also detailed the interactions between cellulose and other macromolecules in intact plant cell walls (Dick-Pérez et al 2011;Earl and VanderHart 1981;Larsson et al 1999;Newman and Hemmingson 1995;Wang and Hong 2016;Wang et al 2016a).…”

Section: Introductionmentioning

confidence: 99%

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

et al. 2017

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The doublet C4 peaks at * 85 and * 89 ppm in solid-state 13 C NMR spectra of native cellulose have been attributed to signals of C4 atoms on the surface (solvent-exposed) and in the interior of microfibrils, designated as sC4 and iC4, respectively. The relative intensity ratios of sC4 and iC4 observed in NMR spectra of cellulose have been used to estimate the degree of crystallinity of cellulose and the number of glucan chains in cellulose microfibrils. However, the molecular structures of cellulose responsible for the specific surface and interior C4 peaks have not been positively confirmed. Using density functional theory (DFT) methods and structures produced from classical molecular dynamics simulations, we investigated how the following four factors affect 13 C NMR chemical shifts in cellulose: conformations of exocyclic groups at C6 (tg, gt and gg), H 2 O molecules H-bonded on the surface of the microfibril, glycosidic bond angles (U, W) and the distances between H4 and HO3 atoms. We focus on changes in the d 13 C4 value because it is the most significant observable for the same C atom within the cellulose structure. DFT results indicate that different conformations of the exocyclic groups at C6 have the greatest influence on d 13 C4 peak separation, while the other three factors have secondary effects that increase the spread of the calculated C4 interior and surface peaks.

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Carbon-13 NMR distinction between categories of molecular order and disorder in cellulose

Cited by 133 publications

References 22 publications

CP-MAS NMR analysis of carbohydrate fractions of soybean hulls and endosperm

CP-MAS NMR analysis of carbohydrate fractions of soybean hulls and endosperm

Spatial relationships between polymers in Sitka spruce: Proton spin-diffusion studies

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

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