Expanding the enantioselectivity of the gas-chromatographic chiral stationary phase chirasil-val-C11 by doping it with octakis(3-O-butanoyl-2,6-di-O-n-pentyl)-gamma-cyclodextrin

Combination of the enantioselective properties of the two versatile gas-chromatographic chiral stationary phases (CSPs) octakis(3-O-butanoyl-2,6-di-O-n-pentyl)-gamma-CD (Lipodex E) 1 and L-valine-diamide-based CSP Chirasil-Val-C11 2 has been realized by doping the chiral polymer 2 with the nonpolymeric selector 1. The resulting mixed-mode CSP Chirasil-Val(gamma-Dex) 3 was found to have a greatly improved enantioselectivity toward proline and aspartic acid (as N-trifluoroacetyl ethyl or methyl esters) in comparison to the single-mode CSP 2. The presence of the CD selector in 3 extended the scope of gas-chromatographic enantioseparations achievable on 2 to underivatized alcohols, terpenes, and other chiral compounds that are exclusively enantioseparated on 1.