cInstitute of Computational Chemistry, University of Girona, Girona 17071, Catalonia, Spain; director@iqc.udg.es 

Enantiomer 4, 371-378, 1999 

 ABSTRACT

In this paper we report the application of quantum similarity measures as a new means of quantitative characterization of molecular chirality. These measures, which are based on the quantitative comparison of electron density functions of R and S enantiomeric structures, clearly demonstrate that the presence, as well as the extent of chirality of these molecules, are reflected not only in the total electron densities, but also in the local shape of small electron density fragments. The results may be regarded as a special manifestation of the recently proven "holographic electron density theorem", asserting that the complete information on the degree of molecular chirality is also contained in any fragment of the fuzzy, boundaryless electron density of molecules. The actual computational scheme provides a simple means for potential applications in molecular similarity studies, where in addition to the qualitative detection of the presence of chirality of enantiomeric molecules and their fragments, the quantum similarity measures and the holographic approach are able to characterize the "extent" of chirality quantitatively based on the actual electron densities. The proposed electron density approach for the quantification of chirality is more sensitive and provides more detail than the conventional nuclear framework approach.

Keywords: Quantum Similarity Measures, Chirality Measures, Molecular Shape Analysis, Quantum Holography, QShAR

Available molecular structures for amino-acids optimized at the HF/6-31g* level of theory. In order to ensure the strict object/mirror image relation of two enantiomeric forms, the molecular geometry has been optimized for one enantiomer only and the structure of the mirror image form has been obtained by appropriately changing the signs of coordinates with respect to a mirror plane.

Last updated: 21 January 2000