Absolute Configuration from Different Multifragmentation Pathways in Light‐Induced Coulomb Explosion Imaging

The absolute configuration of individual small molecules in the gas phase can be determined directly by light‐induced Coulomb explosion imaging (CEI). Herein, this approach is demonstrated for ionization with a single X‐ray photon from a synchrotron light source, leading to enhanced efficiency and faster fragmentation as compared to previous experiments with a femtosecond laser. In addition, it is shown that even incomplete fragmentation pathways of individual molecules from a racemic CHBrClF sample can give access to the absolute configuration in CEI. This leads to a significant increase of the applicability of the method as compared to the previously reported complete break‐up into atomic ions and can pave the way for routine stereochemical analysis of larger chiral molecules by light‐induced CEI.     

Coulomb Explosion Imaged Cryptochiral (R,R)‐2,3‐Dideuterooxirane: Unambiguous Access to the Absolute Configuration of (+)‐Glyceraldehyde

The absolute configuration of (R,R)‐2,3‐dideuterooxirane, which has been independently determined using Coulomb explosion imaging, has been unambiguously chemically correlated with the stereochemical key reference (+)‐glyceraldehyde. This puts the absolute configuration of D (+)‐glyceraldehyde on firm experimental grounds.     

Cover Picture: Ab Initio Calculation of Parity‐Violating Chemical Shifts in NMR Spectra of Chiral Molecules (ChemPhysChem 4/2003)

The cover picture shows an intriguing effect in molecular systems, which is caused by the parity‐violating weak interactions: The chemical shifts of magnetic nuclei are predicted to differ for the two enantiomers of a chiral compound! While in the R enantiomer the nucleus (red) of the yellow center gives rise to the red NMR signal, the corresponding nucleus of the S enantiomer (green) is expected to absorb at a slightly different frequency. The ab initio approach presented by Laubender and Berger on pp. 395–399 allows for a prediction of the resulting parity‐violating line splitting (shown in the black curve) and for the identification of molecular candidates that are well‐suited to the first successful measurement of parity‐violating effects in molecules.