Cross-polarization magic angle spinning polymorphism

Harris, R.K. Say, B.J. Yeung, R.R. Fletton, R.A. Lancaster, R.W. Cross-polarization/magic-angle spinning NMR studies of polymorphism androstanolone. Spectro-chim. Acta, Part A 1989, 45A (4), 465 69. 

Cross-polarization/magic-angle spinning NMR studies of polymorphism cortisone acetate. Spectrochim. Acta, Part A 1990, 46A (6), 927-935. 

RK Harris, BJ Say, RR Yeung, RA Fletton, RW Lancaster. Cross-polarization/ magic-angle spinning NMR studies of polymorphism androstanolone. Spectrochim Acta 45A 465-469, 1989. 

Solid-state C NMR spectroscopy (SS-NMR) is a powerful and sensitive technique for polymorph characterization and differentiation. Since different polymorphs have different crystal structures, the chemical environment of at least a few of the atoms will differ from one structure to another. This technique also provides valuable crystallographic information, such as the number of crystallo-graphically independent molecules in the crystal structure due to doubled peaks for the same C atom. In addition to C NMR, N CP-MAS NMR (cross-polarized magic-angle spinning) is useful for characterizing polymorphic systems, for example, polymorphs of sulfathiazole, those containing N-heterocycles, and neutral co-crystal versus salt formation. ... 

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