Abstract
An original chiral selector, namely the prop-2-enyl 3α-(N-phenylcarbamate)-7α,12α-dihydroxy-5β-cholan-24-oate, is bonded onto the silica surface by three different grafting modes. The influence of the total structure of the chiral stationary phases (CSPs) on enantioseparation is studied. These CSPs are prepared in two steps. In the first step, the silica surface is reacted with one of the following reagents: 1) (3-mercaptopropyl)trimethoxysilane, yielding a rather monomeric support, 2) chlorodimethylsilane, leading to a monomeric material, or 3) triethoxysilane, affording a polymeric packing. In the second step, the chiral selector is bonded onto the modified silica structures to provide the corresponding stationary phases SH, CDS, and TES, respectively. The CSP SH shows the poorest column performance. CSPs CDS and TES show similar mass transfer kinetics; this highlights the good behaviour of the polymeric packing. CSP TES displays globally the highest enantioselectivity and is found to be extremely stable despite its use over months. The silanization reaction with triethoxysilane provides a suitable support for chiral stationary phases.
ACKNOWLEDGMENTS
The authors would like to acknowledge Pr. G. Coquerel (UC2M2, UPRES EA 2659, IRCOF, Université de Rouen, France) for his gift of the hydantoins samples and Pr. D. Villemin (URA CNRS 480, ISMRA-Université de Caen, France) for his donation of the binaphthyl derivatives. This work has been funded by a grant (L. V.-C.) from the Ministère de la Recherche et Technologie (France).