Spectroscopy cross polarized magic-angle

Solid state C-NMR spectroscopy (cross-polarization/magic angle spinning NMR spectroscopy) (structure, organization of the chains, indication of degree of crystallinity)... 

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. 

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... 

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

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. 

In recent years new NMR techniques offering broad applications in stereochemical analysis have come into use. A prominent example is 2D-NMR (both 2D-resolved and 2D-correlated spectroscopy), which has been extensively applied to biopolymers (149-151). Its use with synthetic polymers has, until now, been limited to but a few cases (152, 153). A further technique, cross-polarization magic-angle spinning spectroscopy (CP-MAS NMR) will be discussed in the section on conformational analysis of solid polymers. 

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. 

The cross-polarization, magic-angle spinning method (CP MAS) has been applied by Myhre and Yannoni50 to cation 19 in the solid state at very low temperatures using 13C NMR spectroscopy. In the initial study, no convincing evidence for a frozen 2-butyl cation was obtained even at — 190°C. However, subsequently they managed to freeze out the equilibration of the 2-butyl cation (19) at —223°C.62 It behaves like a normal secondary trivalent carbocation. 

Correlating positively with the hydrophobicity of the solvent, different fractions of inactivated active centers were measured in different solvents with solid-state NMR spectroscopy (13C-cross-polarization/magic angle spinning (MAS) NMR) (Burke, 1992). Just as with tritiated water (see above), immediate desorption of water molecules from the protein surface was observed after addition to the organic solvent. 

Both of these methods have been used for DOM isolation from major rivers and the surface ocean, and the general characteristics of these fractions of DOM are presented in Table I. The major C functional groups of humic substances and ultrafiltered DOM (UDOM) have been characterized by solid-state, cross-polarization magic angle spinning 13C nuclear magnetic resonance (NMR) spectroscopy. The samples of humic substances that were characterized by NMR spectroscopy were collected from the Amazon River... 

Knicker, H. (2000b). Solid-state 2-D double cross polarization magic angle spinning 1SN 13C NMR spectroscopy on degraded algal residues. Org. Geochem. 31,337-340. 

CP-MAS cross-polarization magic-angle spinning (NMR spectroscopy)... 

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