title: Temperature-Triggered Switchable Helix-Helix Inversion of Poly(phenylacetylene) Bearing l-Valine Ethyl Ester Pendants and Its Chiral Recognition Ability.
abstract: A phenylacetylene containing the l-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh₄) to produce the corresponding one-handed helicalcis-poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not observed in highly polar solvents, such asN,N'-dimethylformamide (DMF). By heating the solution of PPAA-Val in chloroform, the sign of the CD absorption became reversed, but recovered after cooling the solution to room temperature. Even after six cycles of the heating-cooling treatment, the helix sense of the PPAA-Val's backbone was still switchable without loss of the CD intensity. The PPAA-Val was then coated on silica gel particles to produce novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). These novel PPAA-Val based CSPs showed a high chiral recognition ability for racemic mandelonitrile (α= 2.18) and racemictrans-N,N'-diphenylcyclohexane-1,2-dicarboxamide (α= 2.60). Additionally, the one-handed helicalcis-polyene backbone of PPAA-Val was irreversibly destroyed to afford PPAA-Val-H by heating in dimethyl sulfoxide (DMSO) accompanied by the complete disappearance of the Cotton effect. Although PPAA-Val-H had the same l-valine ethyl ester pendants as itscis-isomer PPAA-Val, it showed no chiral recognition. It was concluded that the one-handed helicalcis-polyene backbone of PPAA-Val plays an important role in the chiral recognition ability.
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. zhouyanli0808022@163.com.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. zhangchunhong97@163.com.
authors.forename: Chunhong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. wukong.s@163.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. liulijia@hrbeu.edu.cn.
authors.forename: Lijia
authors.initials: L
authors.lastname: Liu
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. az106321@126.com.
authors.forename: Taotao
authors.initials: T
authors.lastname: Yang
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. dhongxing@hrbeu.edu.cn.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Dong
authors.affiliation: Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan. satoh@eng.hokudai.ac.jp.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Satoh
authors.affiliation: Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China. okamoto@apchem.nagoya-u.ac.jp.|Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan. okamoto@apchem.nagoya-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Okamoto
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D002942:Circular Dichroism; D005019:Ethyl Ethers / Q000737:chemistry*; D008968:Molecular Conformation; D056951:Photoelectron Spectroscopy; D058105:Polymerization; D066244:Proton Magnetic Resonance Spectroscopy; D013237:Stereoisomerism; D013696:Temperature; D014633:Valine / Q000737:chemistry*
chemical_list: D005019:Ethyl Ethers; C519145:poly(phenylacetylene); D014633:Valine; D000114:Acetylene
keywords: chiral stationary phases; cis-to-trans isomerization; helical poly(phenylacetylene); helix-helix inversion; temperature-triggered