Synthesis and chiral recognition of helical poly(phenylacetylene)s bearing l‐phenylglycinol and its phenylcarbamates as pendants

Abstract

A series of novel stereoregular one‐handed helical poly(phenylacetylene) derivatives (PPA‐1 and PPA‐1a∼g) bearing l‐phenylglycinol and its phenylcarbamate residues as pendants was synthesized for use as chiral stationary phases (CSPs) for HPLC, and their chiral recognition abilities were evaluated using 13 racemates. The phenylcarbamate residues include an unsubstituted phenyl, three chloro‐substituted phenyls (3‐Cl, 4‐Cl, 3,5‐Cl2), and three methyl‐substituted phenyls (3‐CH3, 4‐CH3, 3,5‐(CH3)2). The acidity of the phenylcarbamate N‐H proton and the hydrogen bonds formed between the N‐H groups of the phenylcarbamate residues were dependent on the type, position, and the number of substituents on the phenylcarbamate residues. The chiral recognition abilities of these polymers significantly depended on the dynamic helical conformation of the main chain with more or less regularly arranged pendants. The chiral recognition abilities seem to be improved by the introduction of substituents on the phenylcarbamate residues, and PPA‐1d bearing the more acidic N‐H groups due to the 3,5‐dichloro substituents, exhibited a higher chiral recognition than the others. PPA‐1d showed an efficient chiral recognition for some racemates, and baseline separation was possible for racemates 5, 11, 12, and 15. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 809–821

Synthesis of Optically Active Poly(diphenylacetylene)s Using Polymer Reactions and an Evaluation of Their Chiral Recognition Abilities as Chiral Stationary Phases for HPLC

“…Ultraviolet (UV) and polarimetric (PM) detectors were used for the detection and identification of the peaks, respectively. As shown in Figure 7c, the different enantiomers of 16 were eluted with retention times of t1 ((-)-enantiomer) and t2 ((+)-enantiomer), The chiral recognition abilities of poly-2S, h-poly-2S and h-poly-(2S 0.36 -co-3 0.64 ) as CSPs for HPLC were evaluated using the various racemic compounds with different functional groups (5-12) including axial (13,14) or planar (15) chiral compounds as well as chiral metal complexes (16)(17)(18) (Figure 6). The packing materials were prepared by coating macroporous silica gel (particle size 7 µm, pore size 100 nm) with DMF solutions of the corresponding polymers [49].…”

“…Optically active poly(phenylacetylene)s with a preferred-handed helicity have been prepared [16] and some of these systems have been reported to exhibit good chiral recognition abilities as CSPs for HPLC because of their preferred-handed helical conformation [17][18][19][20][21][22][23][24][25][26]. However, very few optically active poly(diphenylacetylene)s have been prepared to date, which has limited research towards evaluating the scope and efficiency of the chiral recognition abilities of these materials [27][28][29][30][31][32][33][34][35].…”

Influence of Helical Structure on Chiral Recognition of Poly(phenylacetylene)s Bearing Phenylcarbamate Residues of L‐Phenylglycinol and Amide Linage as Pendants

“…N‐(4‐Ethynylbenzoyl)‐ L ‐phenylglycinol ( PA ) was prepared according to the previously reported method . 3,4‐Dichlorophenyl isocyanate (purity 98%) was purchased from Sun Chemical Technology (Shanghai, China).…”

“…Many kinds of synthetic polymers have also been prepared as the CSPs for HPLC, and some of them exhibit excellent chiral recognition abilities . Among these synthetic polymers, the helical poly(phenylacetylene) derivatives with stereoregular structures showed high chiral recognition abilities as CSPs . The poly(phenylacetylene)s possess dynamic helical conformations, and the change of the helical pitch and inversion of the helicity can be achieved by changing their functional pendants or applying external stimuli, such as temperature and solvents.…”

“…Previously, we synthesized a series of poly(phenylacetylene) derivatives having helical conformations to use as the CSPs for HPLC, which include those bearing L ‐phenylglycinol and its phenylcarbamate residues as pendants, and discussed the influence of different L‐amino acid derivatives on the helical structures of the stereoregular main chains and chiral recognition abilities, etc . In this study, based on our previous studies, four poly(phenylacetylene) derivatives ( PPA-1 , PPA-2 , PPA-3 , PPA-4 ) bearing the phenylcarbamate residues of L ‐phenylglycinol and an amide linkage as pendants were prepared to use as the CSPs for HPLC.…”