Hyperpolarization Methods and Their Applications for the Investigation and Discrimination of Enantiomers in NMR
A. Mames, M. Pietrzak, T. RatajczykDue to the fact that the magnetic interactions, which are the fundamentals of NMR spectroscopy, are the same for a pair of enantiomers, NMR does not make it possible to study molecular chirality directly. Several methods that enable indirect discrimination of enantiomers have been developed to address this issue, and consequently, NMR spectroscopy finds widespread use in the study of chiral substances. However, regardless of whether we use known indirect or anticipated direct methods, the limiting factor in many cases is the sensitivity of NMR spectral measurements. One of the most essential methods that can enhance a weak NMR signal is hyperpolarization, which can enhance NMR signals by several orders of magnitude. Hyperpolarization methods facilitate the usage of NMR applications for problems that cannot be investigated via standard NMR methods. We describe how hyperpolarization can be utilized to facilitate the usage of NMR methods for the discrimination and investigation of enantiomers. First, we present the general concepts of hyperpolarization. Next, we present specific hyperpolarization approaches, and describe how they can facilitate NMR applications for issues concerning enantiomers. Finally, possible perspectives on the applications of hyperpolarization in the analysis of various issues of chirality will be presented briefly.