Advances in NMR spectroscopy of small molecules in solution

Abstract

This chapter discusses advances in small molecule NMR in solution and covers articles from 2020 or 2021. After a short introduction, the second, major, section covers the determination of three-dimensional structures of organic molecules in solution. New methods for acquiring and interpreting residual dipolar coupling and residual chemical shift anisotropies are discussed, along with new orienting media to measure these parameters. The use of density functional theory calculations to aid in 3D structure elucidation is covered. Several new machine learning and artificial intelligence programs that aid in identifying unknown compounds are described. The third section covers pulse sequence developments and means of more rapid data acquisition. Using sequential and/or simultaneous acquisition of two to ten spectra in a single experiment is featured. Discussion of non-uniform sampling mainly focuses on choices for acquiring and processing NUS data sets. The fourth section covers developments in benchtop NMR spectrometers, including hardware improvements, methods for overcoming their limited sensitivity and real-life applications of these spectrometers. The final section covers the use of NMR for investigating complex mixtures, including programs designed to identify individual components in natural product mixtures.