Resolving DOSY spectra of isomers by methanol‐d<sub>4</sub> solvent effects

Reile, Indrek; Aspers, Ruud L. E. G.; Feiters, Martin C.; Rutjes, Floris P. J. T.; Tessari, Marco

doi:10.1002/mrc.4587

Cited by 7 publications

(6 citation statements)

References 42 publications

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“…It is well known that the molecular mass is not the unique parameter affecting diffusion ; for example, the solvent, the shape of the molecule and intermolecular pi‐stacking can have a significant effect . We note that the diffusion coefficients of the 4 substrates are in reverse order of their molecular mass, even if the masses differ by only 4 % (case of 4,4’‐bipyridyl and dimethylnicotinamide) …”

Section: Resultsmentioning

confidence: 74%

Single‐Scan Diffusion‐Ordered NMR Spectroscopy of SABRE‐Hyperpolarized Mixtures

et al. 2019

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The analysis of complex mixtures of dissolved molecules is a major challenge, especially for systems that gradually evolve, e. g., in the course of a chemical reaction or in the case of chemical instability. 1D NMR is a fast and non‐invasive method suitable for detailed molecular analysis, though of low sensitivity. Moreover, the spectral resolution of proton, the most commonly used and most sensitive stable isotope in NMR, is also quite limited. Spatially encoded (SPEN) experiments aim at creating in one acquisition a 2D data set by simultaneously performing different 1D sub‐experiments on different slices of the NMR tube, at the price of an extra loss of sensitivity. Choosing translational diffusion coefficients as the additional dimension (the so‐called DOSY approach) helps to recover proton spectra of each molecule in a mixture. The sensitivity limitation of SPEN NMR can, on the other hand, be addressed with hyperpolarization methods. Within hyperpolarization methods, signal amplification by reversible exchange (SABRE), based on parahydrogen, is the cheapest and the easiest one to set up, and allows multi‐shot experiments. Here we show that the spectra of a mixture's components at millimolar concentration are resolved in few seconds by combining the SABRE, SPEN and DOSY concepts.

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Section: Resultsmentioning

confidence: 74%

Single‐Scan Diffusion‐Ordered NMR Spectroscopy of SABRE‐Hyperpolarized Mixtures

et al. 2019

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“…As reported, methanol- d 4 is more suitable as a solvent than DMSO- d 6 or CDCl 3 for molecules with different numbers of hydroxyl groups, because methanol- d 4 is a protic solvent and hence accepts and donates hydrogen bonds. , Different solvation intensities between the solutes and methanol- d 4 are the main reason for the pseudoseparation in the DOSY spectrum. Although the molecular weight of DMO is the biggest, EG, MG, and ethanol diffuse slower than DMO in methanol- d 4 because they contain a diverse number of hydroxyl groups and form stronger hydrogen bonds with methanol- d 4 . EG has two hydroxyl groups and diffuses slowest.…”

Section: Resultsmentioning

confidence: 99%

DOSY Plus Selective TOCSY: An Efficient NMR Combination for Analyzing Hydrogenation/Hydrogenolysis Mixtures of Biomass-Derived Platform Compounds

et al. 2018

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Analyzing the mixtures obtained from hydrogenation or hydrogenolysis reactions of biomass-derived platform chemicals is challenging work. With the development and improvement of NMR techniques, the NMR spectrometer proves to be an alternative and highly efficient piece of equipment for the rapid analysis of complex mixtures without the need for tedious purification. Herein, diffusion-ordered spectroscopy (DOSY) is applied in analyzing four model mixtures, which consist of the reactants and products from hydrogenation/hydrogenolysis reactions of biomass-derived platform chemicals. The results show that the DOSY technique can pseudoseparate most components in the model mixtures. The 1D selective gradient TOCSY technique is used as a supporting tool in the cases where the DOSY technique cannot clearly distinguish between the components of the mixtures. This is generally a problem when components in the mixture have very similar diffusion coefficients or severe overlap of peaks. The results show that DOSY and 1D selective gradient TOCSY techniques make a strong combination for complex mixture analyses.

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“…However, the DOSY method has generally failed to identify the isomeric species of similar size and structure because of their similar diffusion coefficients. Therefore, recent studies on the DOSY technique have focused on developing strategies for the separation of isomeric species [9][10][11][12][13][14]. The DOSY method has been also applied to carbohydrate chemistry as a tool for the separation and analysis of mono-, di-, oligo-, and polysaccharides, as well as for the structural analysis of metal-complexed carbohydrates [15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%