Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002
EXPERIMENTS AND MODELS IN ENANTIORECOGNITION
BY CHIRAL STATIONARY PHASES
Darko KONTREC, Vladimir VINKOVIC, and Vitomir SUNJIC
Rudjer Boskovic Institute, P. O. Box 180, 10002 Zagreb, Croatia
Aesthetically motivated supramolecular synthesis based on symmetry, topology, and network properties represent a distinct aim for subjects such as crystal engineering or chiral recognition. Enantiorecognition represents a bottom line process which enables separation of enantiomers by chromatography on chiral stationary phases (CSPs).
CSPs based on assemblies of planar, homo- or heteroaromatic branching units, usually with one or two chiral subunits and a spacer that enables binding to silica gel, are known as Pirkle-type or brush-type CSPs and are repeatedly reported.1-3We entered the field of enantioseparation by developing two main groups of CSPs; the first group (I-III) is based on derivatives of persubstituted, p-basic aromatic ring,4-6 the second CSPs (IV-V) are derived from 4-substituted 3,5-dinitrobenzoic acid derivatives, which serve as the p-acidic branching unit.7
Rationale behind the synthesis of over 50 representatives of CSPs I-V, and correlation of their enantioseparation ability to their conformational and structural properties, in particular H-bonding ability and p-acid/base interactions, will be presented. Separation of specific groups of racemic analytes, as e.g. a-aryloxypropionic acids, 4-substituted 1,4-dihydropyrimidines, and 1,4-benzodiazepines is achieved with specifically designed CSPs; mechanisms of enantioseparation, and the observed enantiomerization of configurationally unstable analytes will be discussed.
1 W. H. Pirkle, J. Chromatogr. A 749 (1996) 19-24.
2 S. Allenmark, V. Schurig, J. Mater. Sci. 7 (1997) 1995-1963.
3 E. R. Francotte, Chimia 51 (1997) 717-725.
4 I. Novak, B. Kovac, D. Kontrec, V. Sunjic, J. Electron Spectr. 199 (2000) 281-286.
5 D. Kontrec, V. Vinkovic, A. Lesac, V. Sunjic, A. Aced, Enantiomer 5 (2000) 333-344.
6 a D. Kontrec, A. Abatangelo, V. Vinkovic, V. Sunjic, Chirality 13 (2001) 294-301; b V. Vinkovic, D. Kontec, V. Sunjic, L. Navarini, F. Zanetti, O. Azzolina, Chirality 13 (2001) 581-587; c A. Abatangelo, F. Zanetti, L. Navarini, D. Kontrec, V: Vinkovic, V. Sunjic, Chirality 13 (2001) 984-992.
7 B. Zafirova, D. Kontrec, V. Vinkovic, V. Sunjic, Chirality (2002) submitted.