Synthesis of Helical Poly(phenylacetylene)s with Amide Linkage Bearing L-Phenylalanine and L-Phenylglycine Ethyl Ester Pendants and Their Applications as Chiral Stationary Phases for HPLC

Novel stereoregular helical poly(phenylacetylene) derivatives (PPA-Phe and PPA-Phg) with an amide linkage bearing L-phenylalanine and L-phenylglycine ethyl ester pendants were synthesized for use as chiral stationary phases (CSPs) in HPLC. The polymers showed different chiral recognition abilities depending on the coating solvents. Both PPA-Phe and PPA-Phg exhibited higher chiral recognitions when coated with CHCl3 by having preferable conformations. Their chiral recognition abilities depended on their molecular weight and optical rotations which were influenced by the polymerization solvents and monomer concentration. PPA-Phe and PPA-Phg showed rather different chiral recognitions, indicating that the benzyl group of the former and the phenyl group of the latter also play important roles in the chiral recognition. A few racemates were completely separated on PPA-Phe or PPA-Phg with separation factors comparable or higher than those obtained on the popular polysaccharide-based CSPs.