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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Lesot, Philippe Luz, Zeev Aroulanda, Christie Zimmermann, Herbert |
| Description | Country affiliation: France Author Affiliation: Lesot P ( RMN en Milieu Orienté, ICMMO, UMR-CNRS 8182, Université de Paris-Sud, Orsay, F-91405, Orsay cedex, France.) |
| Abstract | Enantiodiscrimination in the NMR spectra of flexible prochiral solutes dissolved in chiral liquid crystals (CLCs) is reviewed and compared with the analog phenomenon in such rigid solutes. In rigid prochiral solutes, the discrimination is brought about by the cancellation of improper symmetry elements upon dissolving in CLC within the frame of solute-solvent ordering mechanisms. If this reduction in symmetry renders the ordering of enantiotopic sites dissimilar, spectral discrimination may be observed. Symmetry considerations indicate that this is only possible for improper nonaxial groups lacking inversion symmetry. Nonrigid prochiral solutes consist of rapidly (on the NMR timescale) interconverting enantiomers, in which the racemization is accompanied by exchange of nonequivalent sites. These sites become, on the average, enantiotopically related, and in CLC, they exhibit spectral discrimination. The mechanism of the effect and the symmetry selection rules are different for the two cases. Specifically, the discrimination in flexible prochiral compounds results from the different ordering of the interchanging enantiomers in CLC. Using Altman's definition of average symmetry (Proc. R. Soc. A, 1967, 298, 184), selection rules for the phenomenon are derived. It follows that chiral discrimination in nonrigid prochiral solutes is much more abundant and can occur in all symmetry types except those possessing inversion. In particular, contrary to earlier thoughts, the effect can occur in compounds with axial symmetry. Illustrative examples of such studies with particular emphasis on compounds with average axial symmetry of the type D(3h), C(3v) and C(3h) are reviewed in this contribution. |
| File Format | HTM / HTML |
| ISSN | 07491581 |
| Issue Number | 10 |
| Journal | Magnetic Resonance in Chemistry |
| Volume Number | 52 |
| e-ISSN | 1097458X |
| Language | English |
| Publisher | Wiley Heyden |
| Publisher Date | 2014-10-01 |
| Publisher Place | Great Britain (UK) |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Discipline Chemistry Liquid Crystals Chemistry Magnetic Resonance Spectroscopy Solvents Stereoisomerism Journal Article Research Support, Non-u.s. Gov't Review |
| Content Type | Text |
| Resource Type | Article |
| Subject | Chemistry Materials Science |
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