Cross-polarization-magic angle solid carbohydrates

Pfeffer, P. E., Hicks, K. B. and Earl, W. L. 1983. Solid state structures of keto-disacchar-ides as probed by 13C cross-polarization, magic angle spinning NMR spectroscopy. Carbohydr. Res. 11, 181-194. 

Figure 9.3 Conventional 13C cross-polarization magic angle spinning (CP/MAS) solid-state NMR spectra of mangrove leaves at different stages of decomposition in estuarine waters. Differences in carbon functionality are defined by the following key characteristic resonances carbohydrates (50-90 ppm) carboxyl (175 ppm) aromatic (90-170 ppm). (Modified from Benner et al., 1990.)...

Charge Densities - CP/MAS NMR Spectroscopy. Recent C NMR studies of solid carbohydrates using the cross-polarization/magic angle spinning (CP/MAS) technique (15) demonstrates that NMR chemical shifts of the Cl, C4 and C6 carbon atoms are considerably displaced, up to 1C ppm, depending on the particular structure. A relation of these shifts to conformation would be valuable in learning whether a conformation is retained in non-crystalline or solution states. 

The insoluble nature of suberin prevents its analysis by conventional NMR spectroscopy. The development of solid sample C-NMR spectroscopy with cross polarization/magic-angle spinning provides an opportunity to obtain spectra of the intact polymer. The NMR spectrum of the cutin polymer from the fruit of Malus pumila indicates, as expected, that the majority of carbons are methylenes (CH2, 20-30 ppm). The spectrum of suberin from 5. tuberosum showed the presence of a high proportion of aliphatic CH2 but also had a large amount of CHOH (60 to 80 ppm) carbon, probably from contaminating cell wall carbohydrates. This presumed carbohydrate material was still present in the residue left after LiAlH4 reduction, whereas the majority of aliphatic CH2 had been removed by this treatment (Fig. 6.4.8). This result shows that not much of the... 

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