Enantioseparation on Helical Poly(diphenylacetylene) Derivatives Obtained by Helicity Induction and Memory Strategy Using Bio-Based Chiral Oils

Abstract

Optically inactive poly(diphenylacetylene) bearing heptyl ester groups (poly-1) formed a preferred-handed helical conformation upon thermal annealing in various bio-based chiral oils, mainly chiral hydrocarbons, as a chiral source through intermolecular noncovalent interactions. Following the removal of the chiral oils, the induced macromolecular helicity of poly-1 remained stable in solution at room temperature, successfully demonstrating helicity memory (h-poly-1). The left-handed helix of h-poly-1 induced by (S)-limonene underwent complete inversion to a right-handed helix upon thermal annealing in (R)-limonene, and this helicity switching process was reversible and repeatable. When used as a chiral stationary phase (CSP) for high-performance liquid chromatography, h-poly-1 exhibited excellent chiral recognition ability comparable to those of commercially available polysaccharide-based CSPs toward biaryl derivatives with multiple hydrogen-bond donor groups, based solely on the macromolecular helicity induced by bio-based chiral hydrocarbons.