ORCID Profile
0000-0002-8083-0658
Current Organisation
University of Zürich
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Publisher: American Chemical Society (ACS)
Date: 24-06-2021
Publisher: American Chemical Society (ACS)
Date: 05-10-2020
DOI: 10.26434/CHEMRXIV.13023164.V1
Abstract: The apparent “boosted mobility” observed by nuclear magnetic resonance (NMR) diffusion measurements is the result of a known artefact. When signal intensities are changing during an NMR diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficient values. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Publisher: American Chemical Society (ACS)
Date: 03-08-2022
DOI: 10.1021/JACS.2C02830
Abstract: In their Comment (DOI: 10.1021/jacs.2c02965) on two related publications by our groups (
Publisher: American Chemical Society (ACS)
Date: 29-03-2021
DOI: 10.26434/CHEMRXIV.14306771.V1
Abstract: A study reported in The Journal of Physical Chemistry Letters (12 (2021) 2370) of “boosted mobility” measured by diffusion NMR experiments contains significant errors in data analysis and interpretation. We carefully reanalyzed the same data and find no evidence of boosted mobility, and we identify several sources of error.
Publisher: American Chemical Society (ACS)
Date: 29-03-2021
DOI: 10.26434/CHEMRXIV.14306771
Abstract: A study reported in The Journal of Physical Chemistry Letters (12 (2021) 2370) of “boosted mobility” measured by diffusion NMR experiments contains significant errors in data analysis and interpretation. We carefully reanalyzed the same data and find no evidence of boosted mobility, and we identify several sources of error.
Publisher: American Chemical Society (ACS)
Date: 05-10-2020
DOI: 10.26434/CHEMRXIV.13023164
Abstract: The apparent “boosted mobility” observed by nuclear magnetic resonance (NMR) diffusion measurements is the result of a known artefact. When signal intensities are changing during an NMR diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficient values. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Publisher: American Chemical Society (ACS)
Date: 26-07-2022
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-01-2021
Abstract: The apparent “boosted mobility” observed by Wang et al . (Reports, 31 July 2020, p. 537) is the result of a known artifact. When signal intensities are changing during a nuclear magnetic resonance (NMR) diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficients. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Publisher: American Chemical Society (ACS)
Date: 02-12-2021
DOI: 10.1021/JACS.1C09455
Abstract: The reported changes in self-diffusion of small molecules during reactions have been attributed to "boosted mobility". We demonstrate the critical role of changing concentrations of paramagnetic ions on nuclear magnetic resonance (NMR) signal intensities, which led to erroneous measurements of diffusion coefficients. We present simple methods to overcome this problem. The use of shuffled gradient litudes allows accurate diffusion NMR measurements, even with time-dependent relaxation rates caused by changing concentrations of paramagnetic ions. The addition of a paramagnetic relaxation agent allows accurate determination of both diffusion coefficients and reaction kinetics during a single experiment. We analyze a copper-catalyzed azide-alkyne cycloaddition "click" reaction, for which boosted mobility has been claimed. With our methods, we accurately measure the diffusive behavior of the solvent, starting materials, and product and find no global increase in diffusion coefficients during the reaction. We overcome NMR signal overlap using an alternative reducing agent to improve the accuracy of the diffusion measurements. The alkyne reactant diffuses slower as the reaction proceeds due to binding to the copper catalyst during the catalytic cycle. The formation of this intermediate was confirmed by complementary NMR techniques and density functional theory calculations. Our work calls into question recent claims that molecules actively propel or swim during reactions and establishes that time-resolved diffusion NMR measurements can provide valuable insight into reaction mechanisms.
No related grants have been discovered for Jan-Philipp Günther.