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