CP/MAS -NMR spectroscopy applied to structure and interaction studies on cellulose I

Larsson, Per Tomas; Hult, Eva-Lena; Wickholm, Kristina; Pettersson, Erik; Iversen, Tommy

doi:10.1016/s0926-2040(99)00044-2

Cited by 181 publications

(164 citation statements)

References 34 publications

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“…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). Dissection of this spectral region, where chemical shifts are highly dependent on conformation, is particularly difficult.…”

Section: Discussionmentioning

confidence: 98%

“…The most detailed published assignments are those of Larsson and co-workers (Larsson et al 1997;Wickholm et al 1998;Larsson et al 1999), who deconvoluted the 80-90-ppm region of the 13 C spectrum into Gaussian and Lorentzian components assigned to crystalline, paracrystalline and non-crystalline cellulose chains and hemicelluloses. In the wood pulp and textile cellulose spectra that these authors examined, it was possible to separate the signals around 84 ppm from C-4 of non-crystalline cellulose into two closely spaced narrow peaks and one very broad underlying peak.…”

Section: Discussionmentioning

confidence: 99%

“…Newman (1999) assigned this signal, in a spectrum from eucalyptus kraft pulp, to C-4 of xylans conformationally aligned with cellulose. Larsson et al (1999) included much of the signal intensity in this region to the upfield wing of the broad band for surface cellulose within aggregates, although xylans were also considered to contribute to this broad band and a small, separate, narrow signal at 82 ppm was assigned to C-4 of xylan in hardwood (Wickholm et al 1998, Teleman et al 2001 and either xylan or glucomannan in softwood pulp (Hult et al 2000).…”

Section: Discussionmentioning

confidence: 99%

“…If surface cellulose chains within aggregates make a major contribution to the intensity in this region (Larsson et al 1999), their contribution to the spin mixing curves would be expected to resemble the spin mixing curve for the 84-ppm signal. The additional contribution from hemicelluloses would then have to be very different, resembling the spin mixing curve for the 80-ppm signal.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Altaner¹,

Apperley²,

Jarvis³

2006

Holzforschung

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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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Plant Biomass Characterization: Application of Solution‐ and Solid‐State NMR Spectroscopy

Hallac

Ragauskas

2013

Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals

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CP/MAS -NMR spectroscopy applied to structure and interaction studies on cellulose I

Cited by 181 publications

References 34 publications

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

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

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

Plant Biomass Characterization: Application of Solution‐ and Solid‐State NMR Spectroscopy

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