Chem. J. Chinese Universities ›› 2021, Vol. 42 ›› Issue (8): 2673.doi: 10.7503/cjcu20210062

• Materials Chemistry • Previous Articles     Next Articles

Effect of Aromatic Substituent on Chiral Recognition of Helical Polyacetylene-based Chiral Stationary Phases for High-Performance Liquid Chromatography

SHI Ge1,2, XU Qian1, DAI Xiao3, ZHANG Jie1, SHEN Jun3(), WAN Xinhua1()   

  1. 1.Beijing National Laboratory for Molecular Sciences,Key Laboratory of Polymer Chemistry and Physics of Ministry of Education,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China
    2.Henan Joint International Research Laboratory of Living Polymerizations and Functional Nanomaterials,Henan Key Laboratory of Advanced Nylon Materials and Application,School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450001,China
    3.Polymer Materials Research Center,College of Materials Science and Chemical Engineering,Harbin Engineering University,Harbin 150001,China
  • Received:2021-01-27 Online:2021-08-10 Published:2021-08-05
  • Contact: WAN Xinhua E-mail:shenjun@hrbeu.edu.cn;xhwan@pku.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51833001)

Abstract:

Three proline-derived acetylene monomers,(S)-2-ethynyl-N-aromatic carbamoyl pyrrolidine, were synthesized and polymerized under the catalysis of (bicyclo[2.2.1]hepta-2,5-diene)chlororhodium(I) dimer and triethyeamine{[Rh(nbd)Cl]2-Et3N}. The chiral recognition ability of the resultant optically active helical polymers as chiral stationary phases(CSPs) toward nine substitutes was evaluated by high-performance liquid chromatography. These polymers displayed satisfactory enantioseparation ability for three hydrogen-bond(HB) donating molecules, benzoin(α=1.35—1.44), 2,2,2-trifluoro-1-(9′-anthryl)ethanol(α=1.11—1.53), and 1,1′-bi(2-naphthol)(α=1.09—1.11), as well as cobalt(Ⅲ) acetylacetonate(α=1.84—2.38) when the mixture of hexane and isopropanol(volume ratio 9∶1) was used as the eluent. Whereas, when pure hexane was employed as the eluent, 2,2-dimethyl-1-phenyl-1-propanol(α=1.12—1.22) was stereoselectively discriminated by three polymers and 2-phenylcyclohexanone(α=1.11) by poly[(S)-2-ethynyl-N-(2′-naphthyl carbamoyl) pyrrolidine]. Based on NMR, Raman spectra, polarimetry, UV-Vis absorption and circular dichroism spectra, along with liquid chromatography, the correlations between aromatic structure and linking position with polymeric helical conformation as well as optical resolving power were investigated. Molecular docking results suggested that the 1-naphthyl group exhibited larger steric effect over 2-naphthyl group, and facilitated the formation of stronger intramolecular HBs, which impeded chiral discrimination toward giant racemates(such as 1,1′-binaphthyl-2,2′-diol). Compared to phenyl, naphthyl favored the enantioselective π-π interactions between polymers and enantiomers, enhancing the selectivity of steric fit and chiral resolving power of CSPs.

Key words: Helical polyacetylene, Chiral stationary phases, Chiral recognition, Enantioselectivity, High-performance liquid chromatography

CLC Number: 

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