Switchable enantioseparation based on macromolecular memory of a helical polyacetylene in the solid state.

Abstract

In the chromatographic separation of enantiomers the order of elution is determined by the strength of diasteromeric interactions between the components of the mixture and a chiral stationary phase. For analytical purposes, it is ideal to have the minor component elute first, whereas in the preparative mode a faster elution of the major component is desirable. Here we describe a stationary phase constructed from a polyacetylene that bears 2,2'-bisphenol-derived side chains in which chirality can be switched in the solid state prior to use. Both the macromolecular helicity of the polymer backbone and the axial chirality of the side chains can be switched in the solid state by interaction with a chiral alcohol, but importantly are maintained after removal of the chiral alcohol because of a memory effect. The chiral stationary phase thus prepared was used to separate the enantiomers of trans-stilbene oxide with the enantiomer elution order determined by the preseparation treatment.