Residual‐Chemical‐Shift‐Anisotropy‐Based Enantiodifferentiation in Lyotropic Liquid Crystalline Phases Based on Helically Chiral Polyacetylenes

Anisotropic NMR spectroscopy, revealing residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) has emerged as a powerful tool to determine the configurations of synthetic and complex natural compounds. The deduction of the absolute in addition to the relative configuration is one of the primary goals in the field. Therefore, the investigation of the enantiodiscriminating capabilities of chiral alignment media becomes essential. While RDCs and RCSAs are now used for the determination of the relative configuration routinely, RCSAs have not been measured in chiral alignment media such as chiral liquid crystals. Herein, we present this application by measuring RCSAs for chiral analytes such as indanol and isopinocampheol in the lyotropic liquid crystalline phase of an L‐valine derived helically chiral polyacetylenes. We have also demonstrated that a single 1D ¹³C−{¹H} NMR spectrum suffices to get the RCSAs circumventing the necessity to acquire two spectra at two alignment conditions.

The residual chemical shift anisotropy can be acquired from enantiomers employing biphasic helically chiral polyacetylene liquid crystal from a single 1D carbon spectrum. The chiral environment of the liquid crystal facilitates diastereomorphous interactions of enantiomers and leads to two different sets of RCSAs. On the basis of two chiral molecules, it has been demonstrated that enantiodiscrimination is feasible.