Very high-resolution H-1 MAS NMR of a natural polymeric material

resumo

The use of ultrafast magic angle spinning (> 30 kHz) in tandem with delayed echo acquisition is shown to yield very high-resolution H-1 MAS NMR spectra of complex natural organic materials. For the first time, very high-resolution H-1 MAS NMR spectra are reported for cork and wood components, two natural materials with great economic importance. The effect of the spinning rate on the H-1 NMR spectra was evaluated with single-pulse acquisition and delayed-echo acquisition. The delayed-echo acquisition spectra presented linewidths as sharp as 67 and 25 Hz. The narrow peaks, characterised by proton spin-spin and spin-lattice relaxation, were assigned to the isotropic chemical shifts and the general spectral features were shown to correlate with the sample chemical structure. The tentative assignments of cork H-1 MAS NMR signals were presented. (C) 1999 Elsevier Science B.V. All rights reserved.

palavras-chave

QUERCUS-SUBER L; ECHO PULSE SEQUENCE; ROTATING SOLIDS; CORK; SPECTRA; LIGNINS; SPECTROSCOPY; HYDRATION; PROTON

categoria

Chemistry; Physics; Spectroscopy

autores

Gil, AM; Lopes, MH; Neto, CP; Rocha, J

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