scholarly journals Natural Products Dereplication by Diffusion Ordered NMR Spectroscopy (DOSY)

2021 ◽  
Author(s):  
Guy Kleks ◽  
Darren C Holland ◽  
Joshua Porter ◽  
Anthony Richard Carroll
Keyword(s):  
Natural Products ◽  
Nmr Spectroscopy ◽  
Diffusion Coefficients ◽  
P Diffusion

Diffusion-ordered NMR spectroscopy (DOSY) can be used to analyze mixtures of compounds since resonances deriving from different compounds are distinguished by their diffusion coefficients (D). Previously, DOSY has mostly been...

scholarly journals Ion Transport Properties and Ionicity of 1,3-Dimethyl-1,2,3-Triazolium Salts with Fluorinated Anions

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1723 ◽  
Author(s):  
Martin Pulst ◽  
Yury Golitsyn ◽  
Detlef Reichert ◽  
Jörg Kressler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Diffusion Coefficients ◽  
Important Class ◽  
Spectroscopy Data ◽  
Ion Conductivities ◽  
Electrochemical Devices ◽  
Pfg Nmr ◽  
Conductive Properties ◽  
Triazolium Salts

1,2,3-Triazolium salts are an important class of materials with a plethora of sophisticated applications. A series of three novel 1,3-dimethyl-1,2,3-triazolium salts with fluorine, containing anions of various size, is synthesized by methylation of 1,2,3-triazole. Their ion conductivity is measured by impedance spectroscopy, and the corresponding ionicities are determined by diffusion coefficients obtained from 1H and 19F pulsed field gradient nuclear magnetic resonance (PFG NMR) spectroscopy data, revealing that the anion strongly influences their ion conductive properties. Since the molar ion conductivities and ionicities of the 1,3-dimethyl-1,2,3-triazolium salts are enhanced in comparison to other 1,2,3-triazolium salts with longer alkyl substituents, they are promising candidates for applications as electrolytes in electrochemical devices.

Phosphorus diffusion in silicon; influence of annealing conditions

2001 ◽  
Vol 669 ◽  
Author(s):  
J. S. Christensen ◽  
A. Yu. Kuznetsov ◽  
H. H. Radamson ◽  
B. G. Svensson
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficients ◽  
Activation Energies ◽  
Boron Diffusion ◽  
Diffusion Mode ◽  
Phosphorus Diffusion ◽  
Annealing Conditions ◽  
Boron Doped ◽  
Arrhenius Dependence ◽  
P Diffusion

ABSTRACTPhosphorus diffusion has been studied in both pure epitaxially grown silicon and Cz silicon, with a substantial amount of impurities like oxygen and carbon. Anneals have been performed in different atmospheres, N2 and dry O2, as well as in vacuum, at temperatures between 810 – 1100°C. Diffusion coefficients extracted from these anneals show no difference for the P diffusion in the epitaxially grown or the Cz silicon. The diffusion coefficients follow an Arrhenius dependence with the activation energy Ea=2.74±0.07 eV and a prefactor D0 = (8±5)×10−4 cm2/s. These parameters differ considerably from the previously reported and widely accepted values (3.66 eV and 3.84 cm2/s, respectively). However, vacuum anneals of the same samplesresult in values close to this 3.6 eV diffusion mode. Furthermore, control anneals of boron doped samples, with similar design as the phosphorus samples, suggest the same trend for boron diffusion in silicon – lower versus higher values of activation energies for nitrogen and vacuum anneals, respectively. These results are discussed in terms of the concentration of Si self-interstitials mediating the diffusion of phosphorus and boron.

scholarly journals Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization

2003 ◽  
Vol 69 (11) ◽  
pp. 6644-6649 ◽  
Author(s):  
Piet N. L. Lens ◽  
Rakel Gastesi ◽  
Frank Vergeldt ◽  
Adriaan C. van Aelst ◽  
Antonio G. Pisabarro ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Diffusion Coefficients ◽  
Metal Sulfide ◽  
Free Water ◽  
Granular Sludge ◽  
Self Diffusion ◽  
Nmr Characterization ◽  
Self Diffusion Coefficient

ABSTRACT The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.

The effect of instrument resolution on diffusion coefficients measured using NMR spectroscopy

2001 ◽  
Vol 34 (7) ◽  
pp. 389-395
Author(s):  
G. H. Galbraith ◽  
J. Guo ◽  
R. C. McLean ◽  
A. S. M. Y. Munsi ◽  
C. H. Sanders
Keyword(s):  
Nmr Spectroscopy ◽  
Diffusion Coefficients ◽  
Instrument Resolution

Strategies and Tools for Structure Determination of Natural Products Using Modern Methods of NMR Spectroscopy

ChemInform ◽  
2005 ◽  
Vol 36 (47) ◽  
Author(s):  
Bross-Walch Nadja ◽  
Till Kuehn ◽  
Detlef Moskau ◽  
Oliver Zerbe
Keyword(s):  
Natural Products ◽  
Nmr Spectroscopy ◽  
Structure Determination ◽  
Modern Methods
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