Günter Majer

Introduction Motion at the molecular level (1) is central for the development of molecular machines and devices. (2) Biology is rich in examples of active movement in molecular systems, which provide inspiration for synthetic chemical analogues. (1c,d,f) The diffusive motion of molecular species can be monitored by dynamic light scattering, (3) fluorescence correlation spectroscopy, (4) or nuclear magnetic resonance (NMR) spectroscopy.

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 amplitudes produces erroneous diffusion coefficients. We show that no boosted molecular mobility is observed when shuffled gradient amplitudes are applied. In their report (1), Wang et al.