Cross-polarized/magic angle spinning

Lindberg, J. J. and Hortling, B. Cross Polarization — Magic Angle Spinning NMR Studies of Carbohydrates and Aromatic Polymers. Vol. 66, pp. 1—22. 

As a consequence of restricted internal mobility in molecules in the crystalline state, nuclei in different conformation environments, but identical in other respects, can produce different signals in 13C cross polarization, magic angle spinning (CPMAS) solid-state NMR. This analysis is not necessarily limited to crystalline regions, since signals of different conformations are resolved if the exchange is slow with respect to the time scale of the NMR experiment. 

Sometimes decomposition reactions can be avoided by carrying out diazotizations in concentrated sulfuric acid. By this method Law et al. (1991) obtained the 1,5-bisdiazonium salt (incorrectly called tetrazonium salt) of l,5-diamino-4,8-dihy-droxy-anthraquinone, which is deprotonated to 2.28. The structure was verified by cross-polarization magic angle spinning (CPMAS) 13C NMR spectroscopy. 

Cross Polarization — Magic Angle Spinning NMR Studies of Carbohydrates and Aromatic Polymers... 

Azo-bis-isobutyronitrile average polymer chain concentration 4-aminotoluene (p-toluidine) Brunauer-Emmet-Teller cross-linking degree Cross Polarization-Magic Angle Spinning Nuclear Magnetic Spectroscopy Cyclic voltammetry N, A-dimethylformamide... 

Table 1. Structural carbon distribution (%) of the humic acids extracted from soil horizons, adopted from Xing (2001). The distribution was calculated from solid state 13C Cross-Polarization Magic-Angle-Spinning (CP/MAS) NMR spectra. Chemical shift assignment for carbon functional groups alkyl 0-50 ppm O-alkyl 50-117 ppm aromatic 107-165 ppm.

High-Resolution Magic Angle Spinning and Cross-Polarization Magic Angle Spinning Solid-State NMR Spectroscopy... 

Sherwin, C.P., Labuza, T.P., McCormick, A., and Chen, B. 2002. Cross-polarization/magic angle spinning NMR to study glucose mobility in a model intermediate-moisture foods system. J. Agric. Food Chem. 50, 7677-7683. 

Asakura, T., Kuzuhara, A., Tabeta, R., and Saito, H. (1985). Conformation characteriz-tion of Bombyx mod silk fibroin in the solid state by high-frequency 13C cross polarization-magic angle spinning NMR, x-ray diffraction, and infrared spectroscopy. Macromolecules 18, 1841-1845. 

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