Identifying Exchangeable Protons in a 1D NMR Spectrum by Spatially Selective Exchange‐Editing

A 1D NMR experiment is proposed to detect exchangeable sites without deuterium exchange. It is based on spatial encoding to yield a 1D exchange edited spectrum. Qualitative information of which signals are exchanging can be extracted at a glance while the acquisition of the spectrum could be carried out in a single scan.

Abstract

Signals undergoing chemical or conformational exchange in one-dimensional NMR spectra are often identified by deuterium exchange. In order to obtain quantitative information about the dynamic processes involved, one frequently used method is EXchange SpectroscopY (EXSY). To detect all exchange processes, the EXSY experiment requires the acquisition of time-consuming two-dimensional spectra. Here we report a faster alternative, an experiment which uses spatial encoding to extract similar information in a 1D exchange-edited experiment. Thereby, all protons are observed at once, but in different slices of the detection volume. The experiment can be carried out in a single scan to identify exchanging sites in a 1D spectrum by changes in signal intensity indicating exchange processes. If the exchanging partner, for example water is in molar excess the exchange-editing method easily identifies mobile protons by negative signals in the 1D ¹H NMR spectrum.

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