Two‐dimensional Pure Isotropic Proton Solid State NMR

Abstract

One key bottleneck of solid‐state NMR spectroscopy is that 1H NMR spectra of organic solids are often very broad due to the presence of a strong network of dipolar couplings. We have recently suggested a new approach to tackle this problem. More specifically, we parametrically mapped errors leading to residual dipolar broadening into a second dimension and removed them in a correlation experiment. In this way pure isotropic proton (PIP) spectra were obtained that contain only isotropic shifts and provide the highest 1H NMR resolution available today in rigid solids. Here, using a deep‐learning method, we extend the PIP approach to a second dimension, and for samples of L‐tyrosine hydrochloride and ampicillin we obtain high resolution 1H‐1H double‐quantum/single‐quantum dipolar correlation and spin‐diffusion spectra with significantly higher resolution than the corresponding spectra at 100 kHz MAS, allowing the identification of previously overlapped isotropic correlation peaks.