FT-IR and 29Si, 27Al, and 19F MAS NMR studies of the adsorption of CdF2, ZnF2, and CuF2 onto montmorillonite K10; activity towards Friedel–Crafts alkylation

1992 ◽  
Vol 70 (9) ◽  
pp. 2398-2404 ◽  
Author(s):  
Fathi M. Asseid ◽  
Jack M. Miller ◽  
James H. Clark
Keyword(s):  
Oxide Layer ◽  
Nmr Spectra ◽  
Benzyl Chloride ◽  
Aluminium Oxide ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Spectroscopic Evidence ◽  
Montmorillonite K10 ◽  
Evidence Rules ◽  
Ft Ir

ZnF2, CdF2, and CuF2 have been adsorbed onto the surface of montmorillonite K10, and the infrared and 19F, 27Al, and 29Si MAS NMR spectra of the resulting reagents over a range of loadings and activation temperatures have been obtained. CuF2 was observed to attack the SiO2 layer and form the complex CuSiF6, ZnF2 tends to attack the aluminium oxide layer, in which Zn isomorphously replaces Al, and forms AlF3 and AlF4− complexes. The spectroscopic evidence rules out the formation of any Al–F and (or) Si–F species as CdF2 is adsorbed on the surface of montmorillonite K10. The reactivity of MF2–K10 reagents towards the Friedel–Crafts reaction of benzene with benzyl chloride varies from one reagent to another. ZnF2–K10 was observed to be the most reactive and CuF2 was the least reactive.

Continuous Flow Hyper-Polarized 129Xe-Mas Nmr Studies of Microporous Materials.

2003 ◽  
Vol 775 ◽  
Author(s):  
Andrei Nossov ◽  
Flavien Guenneau ◽  
Marie-Anne Springuel-Huet ◽  
Valérie Montouillout ◽  
Jean-Pierre Cognec ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Original Design ◽  
Nmr Studies ◽  
Powder Samples ◽  
Angle Spinning

Summary:A Magic Angle Spinning (MAS) NMR probe has been designed allowing the in-situ measurements of NMR spectra of working catalyst. The probe was built following the original design of M. Hunger [Hunger, 1995 #2]. It allows the magic angle spinning of powder samples up to 3.5 kHz, under gas flowing conditions, and at temperatures up to 573K.

A multinuclear MAS NMR study of the short-range structure of fluorophosphate glass

1992 ◽  
Vol 7 (7) ◽  
pp. 1892-1899 ◽  
Author(s):  
R.K. Brow ◽  
Z.A. Osborne ◽  
R.J. Kirkpatrick
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectroscopic Studies ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Nmr Studies ◽  
Nmr Study ◽  
Fluorophosphate Glass ◽  
Angle Spinning

We have examined the bonding arrangements in Na–P–O–F and Na–Al–P–O–F glasses using 19F, 27Al, and 31P solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. For the Al-free series of glasses, the 19F NMR spectra are dominated by peaks near +90 ppm, representative of F terminating P-chains. The formation of these bonds has little effect on the 31P chemical shifts, indicating that F preferentially replaces bridging oxygen on the phosphate tetrahedra, consistent with previous NMR studies of crystalline fluorophosphates and other spectroscopic studies of fluorophosphate glass. For the Na–Al–P–O–F glasses, 27Al NMR detects only octahedral Al-sites, the 19F NMR spectra include a second peak near −12 ppm due to F bonded to Al, and the 31P NMR spectra contain signals due to Q1-sites with one or more Al next-nearest neighbors. The relative intensity of the two 19F peaks correlates well with previous spectroscopic studies and shows that a greater fraction of F–P bonds forms when the base glass is remelted in NH4HF2.

Solid-State 29Si VACP/MAS NMR Studies of Silicon-Accumulating Plants: Structural Characterization of Biosilica Deposits

2000 ◽  
Vol 55 (6) ◽  
pp. 459-461 ◽  
Author(s):  
Rüdiger Bertermann ◽  
Reinhold Tacke
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Mas Nmr ◽  
Typical Pattern ◽  
Nmr Studies ◽  
Polysilicic Acid ◽  
Freeze Dried ◽  
Pattern Characteristic

A series of silicon-accumulating plants [different Equisetum (horse tail) species, Echium vulgare, and Symphytum officinale] were studied by solid-state 29Si NMR experiments. For this purpose, selected parts of these plants were freeze-dried and then investigated by solid-state 29Si VACP/MAS NMR spectroscopy. The 29Si NMR spectra of these plants are quite similar and exhibit the typical pattern characteristic of polysilicic acid (amorphous silica).

NMR studies of 1-phenylazo-3-substituted-2-naphthols in solution and in the solid state

1990 ◽  
Vol 55 (1) ◽  
pp. 193-201 ◽  
Author(s):  
Antonín Lyčka ◽  
Miroslav Nečas ◽  
Josef Jirman ◽  
Jaroslav Straka ◽  
Bohdan Schneider
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Nmr Spectra ◽  
Equilibrium Mixture ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
Cp Mas Nmr ◽  
Hydrazone Form

The 1H and 15Nα-enriched 1-phenylazo-3-X-2-naphthols, where X = COOH (I), X = COOCH3 (II), and X = CONHC6H5 (III), have been measured in various solvents. The values of 1J(15Nα, H) and σ(15N) indicate that in CDCl3, C6D6, CCl4, and CD3NO2 solutions the compounds I and III exist practically completely in their hydrazone forms. The hydrazone form is stabilized by the hydrogen bond of COOH or CONH protons to the C(2)=O group. The compound II represents an equilibrium mixture of azo and hydrazone forms, since it cannot form a similar hydrogen bond. Moreover, the 15N NMR spectra of compounds I-III have been measured in solid state by the CP/MAS technique. The results indicate the existence of two conformers differing by the conformation of COOCH3 group in compound II, which is supported by the 13C CP/MAS NMR spectrum of compound II.

scholarly journals Sensitivity gains, linearity, and spectral reproducibility in nonuniformly sampled multidimensional MAS NMR spectra of high dynamic range

2014 ◽  
Vol 59 (2) ◽  
pp. 57-73 ◽  
Author(s):  
Christopher L. Suiter ◽  
Sivakumar Paramasivam ◽  
Guangjin Hou ◽  
Shangjin Sun ◽  
David Rice ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Mas Nmr ◽  
High Dynamic

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

scholarly journals Shared and unique metabolic features of the malignant and benign thyroid lesions determined with use of 1H HR MAS NMR spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnieszka Skorupa ◽  
Mateusz Ciszek ◽  
Ewa Chmielik ◽  
Łukasz Boguszewicz ◽  
Małgorzata Oczko-Wojciechowska ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Univariate Analysis ◽  
Mas Nmr ◽  
Metabolic Reprogramming ◽  
Benign Lesions ◽  
Chronic Thyroiditis ◽  
Malignant Lesions ◽  
Metabolic Heterogeneity ◽  
Benign Thyroid ◽  
Thyroid Lesions

AbstractThe purpose of this work was to investigate the distinct and common metabolic features of the malignant and benign thyroid lesions in reference to the non-transformed tissue from the contralateral gland (chronic thyroiditis and colloid goiter). 1H HR MAS NMR spectra of 38 malignant lesions, 32 benign lesions and 112 samples from the non-tumoral tissue (32 from chronic thyroiditis and 80 samples from colloid goiter) were subjected both to multivariate and univariate analysis. The increased succinate, glutamine, glutathione, serine/cysteine, ascorbate, lactate, taurine, threonine, glycine, phosphocholine/glycerophosphocholine and decreased lipids were found in both lesion types in comparison to either colloid goiter or chronic thyroiditis. The elevated glutamate and choline, and reduced citrate and glucose were additionally evident in these lesions in reference to goiter, while the increased myo-inositol—in comparison to thyroiditis. The malignant lesions were characterized by the higher alanine and lysine levels than colloid goiter and thyroiditis, while scyllo-inositol was uniquely increased in the benign lesions (not in cancer) in comparison to both non-tumoral tissue types. Moreover, the benign lesions presented with the unique increase of choline in reference to thyroiditis (not observed in the cancerous tissue). The metabolic heterogeneity of the non-tumoral tissue should be considered in the analysis of metabolic reprogramming in the thyroid lesions.

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