Computational modeling of capillary electrophoretic behavior of primary amines using dual system of 18-crown-6 and β-cyclodextrin

Abdalla A. Elbashir, FakhrEldin O. Suliman

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Using capillary electrophoresis (CE) three chiral primary amine compounds 1-aminoindan (AI), 1-(1-naphthyl)ethylamine (NEA) and 1,2,3,4-tetrahydro-1-naphthylamine (THAN), exhibited only partial or no separation when β-cyclodextrin (βCD) was used as chiral selector. The use of 18-crown-6 (18C6) as a second additive with βCD resulted in an enhanced separation. A molecular modeling study, using molecular mechanics and the semiempirical PM6 calculations, was used to help explaining the mechanism of the enantiodifferentiation and to predict the separation process. Optimization of the structures of the complexes by the PM6 method indicate that the poor separation obtained in the presence of the βCD chiral selector alone is due to the small binding energy differences (ΔΔE) of 4.7, 1.1 and 1.2kcalmol-1 for AI, NEA and THAN, respectively. In the presence of 18C6 it was suggested that a sandwich compound between 18C6, amine and βCD is formed. Theoretical calculations show that a significant increase in the binding energy is obtained for the sandwich compounds indicating strong hydrophobic and van der Waals interactions that show enhanced enantiodifferentiation.

Original languageEnglish
Pages (from-to)5344-5351
Number of pages8
JournalJournal of Chromatography A
Volume1218
Issue number31
DOIs
Publication statusPublished - Aug 5 2011

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Keywords

  • CE
  • Chiral separation
  • Crown ether
  • Cyclodextrin
  • Primary amines
  • Sandwich compounds

ASJC Scopus subject areas

  • Biochemistry
  • Analytical Chemistry
  • Organic Chemistry

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