A carbon-13 nuclear magnetic resonance study of solid tetracyclines

1987 ◽  
Vol 65 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Sandra Mooibroek ◽  
Roderick E. Wasylishen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Pulse Sequence ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Magic Angle Sample Spinning ◽  
Nuclear Magnetic

Magic angle sample spinning and proton/carbon-13 cross-polarization techniques have been used to obtain high resolution solid state 13C nuclear magnetic resonance spectra of several tetracycline antibiotics. Carbon-13 resonances in the solid state are assigned by measuring the extent of dipolar broadening due to neighbouring quadrupolar nuclei and by using a pulse sequence that suppresses non-quaternary carbon resonances. The observed 13C chemical shifts are discussed in light of the known solid state structures derived from X-ray diffraction, and are compared with those in solution. It is shown that the solid state nuclear magnetic reosnance technique is capable of clearly distinguishing between the neutral and zwitterionic forms of the tetracycline free bases.

Solid-state nuclear magnetic resonance study of the structure of lanthanum phosphate crystals and glasses

2000 ◽  
Vol 15 (11) ◽  
pp. 2463-2467 ◽  
Author(s):  
Nancy E. Rashid ◽  
Brian L. Phillips ◽  
Subhash H. Risbud
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Phosphate Glasses ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Lanthanum Phosphate ◽  
Nuclear Magnetic

Lanthanum phosphate glasses were synthesized by melt quenching and characterized by x-ray diffraction, electron microprobe analysis, and solid-state nuclear magnetic resonance spectroscopy. A range of compositions near the metaphosphate composition (75 mol% P2O5) was examined. Comparison of 31P chemical shifts and shielding anisotropies of glasses with those of the crystalline phases of La(PO3)3 (metaphosphate) and LaP5O14 (pentaphosphate) were consistent with the presence of primarily chainlike Q2 phosphate groups.

A carbon-13 CP/MAS nuclear magnetic resonance study of several 1,4-disubstituted benzenes in the solid state

1989 ◽  
Vol 67 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Glenn H. Penner ◽  
Roderick E. Wasylishen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nuclear Magnetic Resonance Study ◽  
Solution Studies ◽  
Temperature Solution ◽  
Cp Mas Nmr ◽  
Nuclear Magnetic

The carbon-13 chemical shifts of several 1,4-disubstituted benzenes in the solid state are reported. At least one of the substituents is unsymmetrical and in most cases this leads to different 13C chemical shifts of C-2 and C-6 and in some cases to different shifts for C-3 and C-5. The 13C chemical shifts observed in the solid state are compared with those measured in solution and, where possible, with those obtained in low temperature solution studies where internal rotation of the unsymmetrical substituent is slow on the 13C chemical shift time scale. Agreement between the chemical shifts observed in the solid state and solution is excellent. The potential application of CP/MAS nuclear magnetic resonance in deducing the conformation of benzene derivatives with two unsymmetrical substituents is discussed. Keywords: carbon-13 CP/MAS NMR, 13C NMR chemical shifts, substituent effects.

Investigation of mineral phases of bone by solid-state phosphorus-31 magic-angle sample-spinning nuclear magnetic resonance

Biochemistry ◽  
1984 ◽  
Vol 23 (25) ◽  
pp. 6115-6120 ◽  
Author(s):  
A. H. Roufosse ◽  
W. P. Aue ◽  
J. E. Roberts ◽  
M. J. Glimcher ◽  
R. G. Griffin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Magic Angle ◽  
Mineral Phases ◽  
Magic Angle Sample Spinning ◽  
Nuclear Magnetic

scholarly journals Degradation of Wheat Straw by Fibrobacter succinogenes S85: a Liquid- and Solid-State Nuclear Magnetic Resonance Study

2005 ◽  
Vol 71 (3) ◽  
pp. 1247-1253 ◽  
Author(s):  
M. Matulova ◽  
R. Nouaille ◽  
P. Capek ◽  
M. Péan ◽  
E. Forano ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Wheat Straw ◽  
Culture Medium ◽  
Nuclear Magnetic Resonance Study ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Fibrobacter Succinogenes ◽  
Nuclear Magnetic

ABSTRACT Wheat straw degradation by Fibrobacter succinogenes was monitored by nuclear magnetic resonance (NMR) spectroscopy and chemolytic methods to investigate the activity of an entire fibrolytic system on an intact complex substrate. In situ solid-state NMR with 13C cross-polarization magic angle spinning was used to monitor the modification of the composition and structure of lignocellulosic fibers (of 13C-enriched wheat straw) during the growth of bacteria on this substrate. There was no preferential degradation either of amorphous regions of cellulose versus crystalline regions or of cellulose versus hemicelluloses in wheat straw. This suggests either a simultaneous degradation of the amorphous and crystalline parts of cellulose and of cellulose and hemicelluloses by the enzymes or degradation at the surface at a molecular scale that cannot be detected by NMR. Liquid-state two-dimensional NMR experiments and chemolytic methods were used to analyze in detail the various sugars released into the culture medium. An integration of NMR signals enabled the quantification of oligosaccharides produced from wheat straw at various times of culture and showed the sequential activities of some of the fibrolytic enzymes of F. succinogenes S85 on wheat straw. In particular, acetylxylan esterase appeared to be more active than arabinofuranosidase, which was more active than α-glucuronidase. Finally, cellodextrins did not accumulate to a great extent in the culture medium.

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