Observation of Enantiomers, Chiral by Virtue of Isotopic Substitution, through Deuterium NMR in a Polypeptide Liquid Crystal

Analysis of the 13C NMR Spectra of Molecules, Chiral by Isotopic Substitution, Dissolved in a Chiral Oriented Environment: Towards the Absolute Assignment of the pro‐R/pro‐S Character of Enantiotopic Ligands in Prochiral Molecules

“…This last result definitely establishes that the molecular orientational order parameters of prochiral, C s symmetry molecules, and their parent derivatives, which are chiral by virtue of the isotopic substitution, are identical in this weakly ordering chiral liquid crystal. This new evidence therefore confirms previous qualitative initial results observed using deuterium NMR spectroscopy in the PBLG phase [5] and shows explicitly that the spectral discrimination between enantiotopic elements in prochiral compounds and between the corresponding isotopic enantiomers involves the same enantiorecognition mechanisms.…”

“…For isotopic enantiomers, the situation is rather different because the origin of their chiral discrimination is a consequence of the fact that two enantiotopic ligands are non equivalent in CLC such as organic solutions of poly-g-benzyl-l-glutamate (PBLG). [5,6] The phenomenon of enantiotopic discrimination in chiral liquid crystalline solvents is due to the change in the symmetry of the intermolecular potential experienced by the solute when the environment is chiral compared with achiral oriented media. [6,7] Due to the chiral environment, no plane of symmetry will be conserved in the orientational probability function in such a way that C s molecules will behave as if it were C 1 , C 2v molecules will behave as if they were C 2 and so on.…”

“…[6,7] Due to the chiral environment, no plane of symmetry will be conserved in the orientational probability function in such a way that C s molecules will behave as if it were C 1 , C 2v molecules will behave as if they were C 2 and so on. [6,8] The chiral discrimination mechanism described above was derived from the analysis of proton-decoupled deuterium NMR spectra, [5] but no investigations using 13 C NMR spectroscopy have been made so far. [1] It is the purpose of this Abstract: We examined and discuss the protonand deuterium-decoupled carbon-13 1D spectrum of a molecule, chiral by virtue of the isotopic substitution, dissolved in a chiral oriented medium which simultaneously exhibits chiral discrimination, enantiomeric enrichment and isotope effect.…”

Analysis of Intramolecular Dynamic Processes in Enantiomeric Diaryl Atropisomers and Related Derivatives by 2H NMR Spectroscopy in Polypeptide Liquid Crystals

“…In the past, some rigid and flexible chiral molecules due to isotopic substitution have been investigated by 2 H NMR spectroscopy in polypeptide LCs, but derivatives exhibiting a conformational exchange detectable by NMR spectroscopy have not yet been explored. [32,33] In addition, it is worthwhile comparing the results obtained for 3 and 4 in order to analyse possible steric isotope effects on 2 H NMR spectra. [34] The MMCs carried out on 4 show that the potential energy profiles for 3 and 4 are identical.…”

An Easy and Scalable Method for the Partial Alignment of Organic Molecules for Measuring Residual Dipolar Couplings

“…[9][10][11][12][13] Liquid-crystalline phases, however, have the disadvantage that a minimal concentration is necessary and therefore a minimal alignment of the molecules in a sample is introduced, which strongly limits the applicability of standard methods for the measurement of coupling constants. [12] An alternative is given by strain induced alignment in a gel (SAG), which is independent of the magnetic field and scalable over a wide range.…”