TY  - JOUR
AU  - Rezaei-Ghaleh, Nasrollah
AU  - Agudo-Canalejo, Jaime
AU  - Griesinger, Christian
AU  - Golestanian, Ramin
TI  - Molecular Diffusivity of Click Reaction Components: The Diffusion Enhancement Question
JO  - Journal of the American Chemical Society
VL  - 144
IS  - 3
SN  - 0002-7863
CY  - Washington, DC
PB  - ACS Publications
M1  - FZJ-2023-01124
SP  - 1380 - 1388
PY  - 2022
AB  - Micrometer-sized objects are widely known to exhibit chemically driven motility in systems away from equilibrium. Experimental observation of reaction-induced motility or enhancement in diffusivity at the much shorter length scale of small molecules is, however, still a matter of debate. Here, we investigate the molecular diffusivity of reactants, catalyst, and product of a model reaction, the copper-catalyzed azide-alkyne cycloaddition click reaction, and develop new NMR diffusion approaches that allow the probing of reaction-induced diffusion enhancement in nanosized molecular systems with higher accuracy than the state of the art. Following two different approaches that enable the accounting of time-dependent concentration changes during NMR experiments, we closely monitored the diffusion coefficient of reaction components during the reaction. The reaction components showed distinct changes in the diffusivity: while the two reactants underwent a time-dependent decrease in their diffusivity, the diffusion coefficient of the product gradually increased and the catalyst showed only slight diffusion enhancement within the range expected for reaction-induced sample heating. The decrease in diffusion coefficient of the alkyne, one of the two reactants of click reaction, was not reproduced during its copper coordination when the second reactant, azide, was absent. Our results do not support the catalysis-induced diffusion enhancement of the components of the click reaction and, instead, point to the role of a relatively large intermediate species within the reaction cycle with diffusivity lower than that of both the reactants and product molecule.
LB  - PUB:(DE-HGF)16
C6  - 35078321
UR  - <Go to ISI:>//WOS:000752924300038
DO  - DOI:10.1021/jacs.1c11754
UR  - https://juser.fz-juelich.de/record/996127
ER  -