Theory and Application of NMR Diffusion Studies

Brand, Torsten; Cabrita, Eurico J.; Berger, Stefan

doi:10.1007/1-4020-3910-7_17

Cited by 16 publications

(24 citation statements)

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“…Similar conclusions can be reached by measuring the self-diffusion coefficient (D) of the compounds in both solvents using pulse-field gradients [27,28]. For 1, the D changes from 4.46 ± 0.07  10 -10 m 2 /s in chloroform-d to 5.62 ± 0.08  10 -10 m 2 /s in methanol-d 4 , indicating a decrease in the apparent molecular radius of ~25% if a Stokes-Einstein diffusion model is assumed [27]. On the other hand, the D for compound 2 goes from 6.45 ± 0.05  10 -10 m 2 /s to 5.75 ± 0.03  10 -10 m 2 /s when going from non-polar aprotic to polar protic media, consistent with an increase in the Stokes radius of ~10% in Aggregation behavior of lipid alkaloids Natural Product Communications Vol.…”

supporting

confidence: 71%

Aggregation Behavior of 6-Isocassine and N-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

Reina¹,

Bottini²,

Bennadji

et al. 2016

Natural Product Communications

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The aggregation behavior of 6-isocassine and N-methyl-6-isocassine, two piperidin-3-ol alkaloids isolated respectively from the barks of Prosopis nigra and P. affinis, was investigated using a combination of NOE experiments and diffusion measurements in solvents of varying polarity and hydrogen bonding capacity. While the NOE enhancements for N-methyl-6-isocassine are positive, regardless of the solvent, those for 6-isocassine shift from negative to positive when going from chloroform-d to methanol-d 4 solution. In addition, despite the self-diffusion coefficients of both compounds being virtually identical in methanol-d 4 , N-methyl-6-isocassine diffuses nearly twice as fast as the non-methylated alkaloid in chloroform-d. The changes in rotational and translational dynamics observed between solvents for 6-isocassine suggest that the molecule forms dimeric head-to-head aggregates in non-polar aprotic environments, a behavior that could help explain the biological mode of action that has been proposed for this type of alkaloids.

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confidence: 71%

Aggregation Behavior of 6-Isocassine and N-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

Reina¹,

Bottini²,

Bennadji

et al. 2016

Natural Product Communications

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“…This simple and fast technique is capable of determining diffusion coefficients of species in solution. As the diffusion coefficient of the hydrogen‐bonded species will differ from their free counterparts, evidence for hydrogen bonding can be found . This slightly less common technique is chosen because infrared spectroscopy (often used to detect hydrogen bonding) is difficult in solution and dynamic light scattering is complicated for systems containing polythiophenes, as they do not only scatter but also absorb the light.…”

Section: Resultsmentioning

confidence: 99%

Study on the formation of a supramolecular conjugated graft copolymer in solution

Hardeman

Willot

Winter

et al. 2013

J. Polym. Sci. Part A: Polym. Chem.

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The formation in solution of a supramolecular graft copolymer bearing conjugated blocks is demonstrated using diffusion ordered NMR spectroscopy (DOSY). A tailor-made poly(3-(2-ethylhexyl)thiophene) (P3EHT) with a phenol end group is synthesized. For this purpose, the chain-growth mechanism of the polymerization of 2-bromo-5-chloromagnesio-3-alkylthiophenes in the presence of a Ni(dppp) catalyst (dppp 5 1,3-bis(triphenylphosphino)propane) is exploited, as it enables the use of functionalized initiators to introduce specific end groups. The soobtained polythiophene was subsequently mixed in solution with poly(4-vinylpyridine) (P4VP) to enable phenol-pyridine hydrogen bonding. The formation of the supramolecular graft copolymer is studied using DOSY-measurements. Based on the results thereof, the amount of P3EHT attached to the P4VP is calculated and the association constant of the hydrogen bond is estimated. V C 2013

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“…A variety of experimental and computational approaches have been used in such efforts . These include detection of intermolecular nuclear Overhauser effects (NOEs) that arise because of spin dipolar interactions between solute and solution components …”

Section: Introductionmentioning

confidence: 99%

Examination of ethanol interactions with Trp‐cage peptide through MD simulations and intermolecular nuclear Overhauser effects

Gerig

2018

J of Physical Organic Chem

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Molecular dynamic (MD) simulations of the model protein Trp‐cage dissolved in 35% ethanol‐water at 298 K have been carried out using conventional force fields. The goal was to develop a better understanding of experimental intermolecular nuclear Overhauser effects (NOEs) that arise from interactions of ethanol methyl groups with hydrogens of the peptide. Cross‐relaxation terms ( σETHNOE) for peptide N‐H hydrogens and several side chain groups were calculated from the MD trajectories. The simulations indicate that water preferentially solvates hydrogens at the peptide termini while ethanol preferentially accumulates at the other hydrogens of the peptide. Most of a calculated NOE arises from interaction of ethanol molecules in the first solvent layer with a peptide hydrogen. Calculated σETHNOE are qualitatively consistent with experimental values but are not in quantitative agreement. Results from MD trajectories calculated by using modified force fields for ethanol intended to reduce peptide‐methyl group interactions do not lead to better agreement between observed and calculated σETHNOE. Possible reasons for the poor predictions of σETHNOE from the MD trajectories are discussed.

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Theory and Application of NMR Diffusion Studies

Cited by 16 publications

References 0 publications

Aggregation Behavior of 6-Isocassine and N-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

Aggregation Behavior of 6-Isocassine and N-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

Study on the formation of a supramolecular conjugated graft copolymer in solution

Examination of ethanol interactions with Trp‐cage peptide through MD simulations and intermolecular nuclear Overhauser effects

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