Electrostatic chiral distinction: Tetrahedral model dimers

Abstract

Although chiral distinction plays a pervasive role in chemistry, a complete understanding of how this takes place is still lacking. In this work, we expand the earlier described minimal requirement of so called four-point interactions (vide infra). We focus on chiral point charge model systems as a means to aid in the dissection of the underlying, operative principles. We also construct models with defined symmetry characteristics. By considering extensive constellations of diastereomeric complexes, we are able to identify emerging principles for chiral distinction. As previously postulated, all the diastereomeric complexes, regardless of their nominal contact-points, possess a chiral distinction energy. In the comparison of complexes, we find that, contrary to chemical intuition, the magnitude of chiral distinction does not correlate with the stability of the complexes, i.e., consideration of low energy complexes may not be an effective way to evaluate chiral distinction. Similarly, we do not find a correlation between the number of contact-points and chiral distinction. Moreover, favorable interactions and facile chiral distinction appear to be unrelated. We also see some tendency for greater chiral distinction in less symmetric systems, although this may not be general. These studies can now form the basis to fold in higher levels of complexity into the models so as to gain further insights into the nature of chiral distinction.

Chirality effects in gas-phase spectroscopy and photophysics of molecular and ionic complexes: contribution of low and room temperature studies

“…Enantiomeric excess in the formation of photoproducts is larger for sites of lower binding affinity to the substrate [256,280]. Theoretical approaches seem to confirm this hypothesis as it has been postulated that chiral recognition is better in higher energy conformers [226,227]. Our study of pseudo-enantiomerism shows the same trend as the differences between quinine and International Reviews in Physical Chemistry 197 quinidine are much more prominent in higher energy conformers.…”

“…The hypothesis that chiral recognition is more prominent in less stable conformers has been suggested already on the basis of calculations on model systems showing transient chirality [226] or asymmetric carbons treated like charge points [227].…”

Chiral Discrimination in Dimers of Diphosphines PH2PH2and PH2PHF

“…Chiral recognition also plays an important role in separation techniques,39–41 supramolecular chemistry,42 and crystallography 43. 44 The possibility of chiral distinction in hydrogen‐bonded complexes has been reviewed in the literature 45. 46 Potential chiral distintion in pnicogen‐bonded phosphines has been explored by some of us 27.…”

Chiral Separation via Molecular Sieving: A Computational Screening of Suitable Functionalizations for Nanoporous Graphene

“…Currently, the enantioselective separation via chromatography is one of the most important techniques for the production of enantiopure compounds for the pharmaceutical, agricultural and food industries . Computational simulation has helped to gain insights into the process of molecular recognition . Several models have been suggested in the past in order to reduce the necessity of empirical rules and chemical intuition.…”