Hydration effects in the carbon-13 CP/MAS NMR spectra of solid (1 →3)-β-D-glucans

1984 ◽  
Vol 17 (3) ◽  
pp. 501-502 ◽  
Author(s):  
C. A. Fyfe ◽  
P. J. Stephenson ◽  
M. G. Taylor ◽  
T. L. Bluhm ◽  
Y. Deslandes ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Mas Nmr ◽  
Cp Mas Nmr

ChemInform Abstract: HIGH-RESOLUTION CARBON-13 CP/MAS NMR SPECTRA OF SOLID CELLULOSE OLIGOMERS AND THE STRUCTURE OF CELLULOSE II

1983 ◽  
Vol 14 (31) ◽  
Author(s):  
R. L. DUDLEY ◽  
C. A. FYFE ◽  
P. J. STEPHENSON ◽  
Y. DESLANDES ◽  
G. K. HAMER ◽  
...  
Keyword(s):  
High Resolution ◽  
Nmr Spectra ◽  
Mas Nmr ◽  
Cellulose Ii ◽  
Cp Mas Nmr

Effects of proton-proton spin exchange in the silicon-29 CP-MAS NMR spectra of the silica surface

1992 ◽  
Vol 96 (10) ◽  
pp. 4027-4034 ◽  
Author(s):  
I Ssuer Chuang ◽  
David R. Kinney ◽  
Charles E. Bronnimann ◽  
Robert C. Zeigler ◽  
Gary E. Maciel
Keyword(s):  
Nmr Spectra ◽  
Spin Exchange ◽  
Silica Surface ◽  
Proton Spin ◽  
Mas Nmr ◽  
Proton Proton ◽  
Cp Mas Nmr

13C CP/MAS-NMR spectra of organic matter as influenced by vegetation, climate, and soil characteristics in soils from Murcia, Spain

2002 ◽  
Vol 82 (4) ◽  
pp. 403-411 ◽  
Author(s):  
A. Faz Cano ◽  
A R Mermut ◽  
R. Ortiz ◽  
M B Benke ◽  
B. Chatson
Keyword(s):  
Organic Matter ◽  
Functional Groups ◽  
Plant Community ◽  
Nmr Spectra ◽  
Climatic Conditions ◽  
Parent Material ◽  
Mas Nmr ◽  
Soil Parameters ◽  
Organic C ◽  
Cp Mas Nmr

Soils in southern Spain are low in organic matter (OM) and nutrients. Understanding the nature and dynamics of OM has potential to improve soil management technologies for sustainable crop production. The objective of this work was to establish the distribution of functional groups in organic-C from these soils using 13C CP/MAS-NMR spectroscopy and to investigate the influence of vegetation, climatic conditions, soil parameters, parent material, and soil order on these functional groups. No statistically significant variability in the distribution of organic-C groups was found as a result of the influence of either soil order or parent material. The content of O-alkyl-C in the soils under the Rhamno-Quercetum plant community was higher (95% probability) than in the soils under the Paronychio-Sideritidetum plant community. Soils located in the mesomediterranean climatic zone displayed a higher content of O-alkyl-C and a lower content of aromatic-C compared to the soils located in the thermomediterranean zone. These differences were statistically significant at 95% of probability. Vegetation and climatic conditions appear to play a major role in the OM decomposition processes in this region. Statistically significant and positive correlations were found between alkyl-C and both cation exchange capacity (CEC) and clay content indicating the recalcitrant nature of these organic compounds. Key words: Organic matter composition, Spanish soils, 13C CP/MAS-NMR spectra, Mediterranean soils, Alfisols, Mollisols, Aridisols

scholarly journals 13C CPMAS NMR as a Tool for Full Structural Description of 2-Phenyl Substituted Imidazoles That Overcomes the Effects of Fast Tautomerization

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3770
Author(s):  
Nikola Burdzhiev ◽  
Anife Ahmedova ◽  
Boris Borrisov ◽  
Robert Graf
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Spectroscopic Method ◽  
Mas Nmr ◽  
Structural Description ◽  
Tautomeric Forms ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

Tautomerization of 2-phenylimidazolecarbaldehydes has not been studied in detail so far, although this process is a well-known phenomenon for imidazole derivatives. That is why we focus our study on a series of 2-phenylimidazolecarbaldehydes and their parent alcohols that were synthesized and studied by detailed 1H and 13C NMR in solution and in the solid state. The apparent problem is that the fast tautomerization impedes the full structural description of the compounds by conventional 13C NMR measurements. Indeed, the 13C NMR spectra in solution exhibit poor resolution, and in most cases, signals from the imidazole ring are not detectable. To avoid this problem, we used 13C CP-MAS NMR as an alternative spectroscopic method for unambiguous spectroscopic characterization of the studied series of 2-phenylimidazoles. The data were analyzed in combination with quantum chemical DFT-GIAO methods by considering the tautomerization process and the intermolecular interactions. The DFT (B3LYP/6-31G(d,p)) calculations allowed to identify and suggest the preferred tautomer in the gas phase and in DMSO solvent, which for alcohols are (2-phenyl-1H-imidazol-4-yl)methanol and its analogs, and for the aldehydes are the 2-phenyl-1H-imidazole-5-carbaldehydes. The gas-phase calculated energy differences between the two possible tautomeric forms are in the range 0.645–1.415 kcal/mol for the alcohols and 2.510–3.059 kcal/mol for the aldehydes. In the DMSO solvent, however, for all compounds, the calculated energy differences go below 1.20 kcal/mol. These data suggest that both tautomeric forms of the studied 2-phenylimidazoles can be present in solution at room temperature. Our data from detailed 2D NMR measurements in the solid state (1H-13C HETCOR and 1H-1H double-quantum coherence MAS NMR) suggested that also in the solid state both tautomers coexist in different crystalline domains. This fact does not obscure the 13C CP-MAS NMR spectra of the studied 2-phenyl substituted imidazoles and suggests this spectroscopic method as a powerful tool for a complete structural description of tautomeric systems with aromatic conjugation.

Residual dipolar splittings in 13C CP/MAS NMR spectra due to quadrupolar halogen nuclei in uracil halides

1994 ◽  
Vol 222 (5) ◽  
pp. 486-492 ◽  
Author(s):  
Bunsow Nagasaka ◽  
Sadamu Takeda ◽  
Nobuo Nakamura
Keyword(s):  
Nmr Spectra ◽  
Mas Nmr ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

Application of deuteriated isotopomers in the analysis of13C CP/MAS NMR spectra of some azo dyes

1991 ◽  
Vol 29 (5) ◽  
pp. 500-505 ◽  
Author(s):  
Jaroslav Straka ◽  
Bohdan Schneider ◽  
Antonín Lyčka ◽  
Josef Jirman
Keyword(s):  
Azo Dyes ◽  
Nmr Spectra ◽  
Mas Nmr ◽  
Cp Mas Nmr

i.r. and 13C-CP-MAS-NMR spectra of pyromellitide and of its precursor based on 4,4′-diaminodiphenylmethane

1990 ◽  
Vol 26 (9) ◽  
pp. 941-945 ◽  
Author(s):  
B Schneider ◽  
P Schmidt ◽  
M Marek ◽  
J Straka ◽  
B Bednář ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Mas Nmr ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr
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