Kinetic Investigation of a Cucurbit[7] uril-Based Pseudo[6]rotaxane System by Microfluidic Nuclear Magnetic Resonance

Abstract

It is challenging to investigate fast supramolecular processes due to the lack of appropriate characterization methods with high structural resolution. In this study, microfluidic nuclear magnetic resonance (μF-NMR) spectroscopy was employed to monitor the kinetics of threading and dethreading of a pseudo [6]rotaxane system. By employing high time resolution μF-NMR, 1H and two-dimensional (2D) rotating frame nuclear Overhauser effect spectroscopy (ROESY) NMR spectra were recorded at any time point within 1.5 s after the onset of the process. This technique enabled the successful identification of kinetic intermediates and rate-determining steps, usually impossible to determine by other spectroscopic techniques. Thus, our study demonstrates the capability of μF-NMR in investigating the mechanism of complex supramolecular systems.