Crystallographic studies for the chiral recognition of the novel chiral stationary phase derived from (+)-(R)-18-crown-6 tetracarboxylic acid

✍ Scribed by Yoshio Machida; Hiroyuki Nishi; Kouji Nakamura

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 171 KB
• Volume: 11
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/(sici)1520-636x(1999)11:3<173::aid-chir1>3.0.co;2-p

✦ Synopsis

Chiral discrimination observed in high-performance liquid chromatography (HPLC) with the novel chiral stationary phase (CSP-18C6I) derived from (+)-(R)-18-crown-6 tetracarboxylic acid [(+)-18C6H 4 ] was investigated by X-ray crystallographic analysis of the complex composed of the R-enantiomer of 1-(1-naphthyl)ethylamine (1-NEA) and (+)-18C6H 4 . Mixtures of 1-NEA (the R-or S-enantiomer) and (+)-18C6H 4 were dissolved in methanol-water (1:1) solution and allowed to stand for crystallization. The R-enantiomer crystallized with (+)-18C6H 4 as a co-crystal, although the S-enantiomer did not. This result was in good agreement with the enantiomer elution order of 1-NEA in CSP-18C6I. The apparent binding constants (K a ) of the enantiomers to the (+)-18C6H 4 obtained from 1 H-NMR experiments also supported the above-mentioned result. The X-ray crystal structure of the 1:1 complex of the R-enantiomer and (+)-18C6H 4 indicated the four sets of hydrogen bond association between the naphthylethylammonium cation and oxygen of polyether ring or carbonyl group of (+)-18C6H 4 .