Investigation of the Crystal Structure for the Direct Chiral Separation Model in High-Performance Liquid Chromatography

• Published in: Analytical Sciences Vol. 11; no. 4; pp. 563 - 568
• Main Authors: OKAMURA, Kimio, DA-TE, Tadamasa, FUJIWARA, Yasuhiro, SUMIDA, Yoshio, TERADA, Syunji, HASHIMOTO, Keiji
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society for Analytical Chemistry 1995; Japan Society for Analytical Chemistry; Japan Science and Technology Agency
• Subjects: Analytical chemistry; Chemistry; chiral discrimination mechanism; Chiral stationary phase; Chromatographic methods and physical methods associated with chromatography; diastereomeric complex; Exact sciences and technology; liquid chromatography; Other chromatographic methods; X-ray crystallography; Nitro compound; Bond length; Separation; Bond angle; HPLC chromatography; X ray spectrometry; Chiral stationary phase; Experimental study; Modeling; Reaction mechanism; Carboxamide; Benzenic compound; Molecular complex; Diastereomer; Bonded stationary phase; Organic compounds; Crystalline structure
• ISSN: 0910-6340; 1348-2246
• DOI: 10.2116/analsci.11.563

(R, S)-N-(3, 5-dinitrophenyl)-α-methylbenzeneacetamide [(R, S)-PPA-DNA] can be resolved into its enantiomer on the chiral stationary phase (CSP) which chemically bonded with (S)-α-methyl-1-naphthylamine. To investigate the mechanism of this chiral discrimination in liquid chromatography, an X-ray crystallographic study of two diastereomeric equimolar complexes was performed. (S)-N Acetyl-α-methyl-1-naphthylamine [(S)-NEA-a] and (R), (S)-PPA-DNA were used as models of the CSP and the analyte, respectively. The crystal structures of both diastereomeric complexes were clarified so that the hydrogen bond and the π-π donor-acceptor intermolecular interaction dominated the chiral discrimination, suggesting that the chiral discrimination was caused by the differences in the binding force and in the number of intermolecular interactions within a combination of the CSP model and the analyte in suitable association. This interpretation of the result of X-ray crystallography agreed with the elution order on chromatography. The correlation between the crystal structure and the proton nuclear magnetic resonance (NMR) spectroscopy is also discussed.