Kinetic characterization of a slow chemical exchange between two sites in N,N-dimethylacetylamide by CEST NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy has provided many powerful tools for the study of dynamic processes. Among the reported methods, chemical exchange saturation transfer (CEST) is more suitable for systems with slow exchange rates, and there will be promising in the detection and dynamic mechanism of metastable substances. It has been widely used in magnetic resonance imaging (MRI), however whether it is applicable in the field of chemical kinetics needs more examples. Here we studied, as a proof of concept, the kinetics of the slow chemical exchange between the two N-methyl protons of N,N-dimethylacetylamide (DMA), exploiting QUantifying Exchange using Z-spectrum (QUEZS) and QUantifying Exchange using Saturation Time (QUEST) methods. It turned out that both of QUEZS and QUEST could give the corresponding exchange rates, showcasing the capability of this method to provide accurate kinetic data under a range of temperatures. Our results clearly demonstrated the reliability of CEST-based techniques as a tool for dynamic kinetics by NMR. (C) 2022 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

Nuclear magnetic resonance (NMR) spectroscopy has provided powerful tools for studying dynamic processes. Chemical exchange saturation transfer (CEST) is suitable for systems with slow exchange rates and shows potential in detecting metastable substances and understanding dynamic mechanisms. This study used QUEZS and QUEST methods to investigate the kinetics of slow chemical exchange in N,N-dimethylacetylamide (DMA). The results demonstrated the reliability of CEST-based techniques in providing accurate kinetic data under different temperatures.