Chiral Recognition by Dissolution DNP NMR Spectroscopy of ¹³C-Labeled <scp>dl</scp>-Methionine

Abstract

A method based on d-DNP NMR spectroscopy to study chiral recognition is described for the first time. The enantiodifferentiation of a racemic metabolite in a millimolar aqueous solution using a chiral solvating agent was performed. Hyperpolarized 13 C-labeled dl -methionine enantiomers were differently observed with a single-scan 13 C NMR experiment, while the chiral auxiliary at thermal equilibrium remained unobserved. The method developed entails a step forward in the chiral recognition of small molecules by NMR spectroscopy, opening new possibilities in situations where the sensitivity is limited, for example, when a low concentration of analyte is available or when the measurement of an insensitive nucleus, like 13 C, is required. The advantages and current limitations of the method, as well as future perspectives, are discussed.