Facile Synthesis of Optically Active and Thermoresponsive Star Block Copolymers Carrying Helical Polyisocyanide Arms and Their Thermo-Triggered Chiral Resolution Ability,ACS Macro Letters

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Facile Synthesis of Optically Active and Thermoresponsive Star Block Copolymers Carrying Helical Polyisocyanide Arms and Their Thermo-Triggered Chiral Resolution Ability
ACS Macro Letters ( IF 5.1 ) Pub Date : 2018-01-05 00:00:00 , DOI: 10.1021/acsmacrolett.7b00875
Qian Wang ₁ , Ben-Fa Chu ₁ , Jia-Hong Chu ₁ , Na Liu ₁ , Zong-Quan Wu ₁

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A left-handed helical poly(phenyl isocyanide) bearing a norbornene unit and a Pd(II) complex on each terminus was prepared. The norbornene terminus was core cross-linked with a bisnorbornene linker via ring-opening metathesis polymerization (ROMP), yielding a star polymer carrying left-handed helical arms decorated with Pd(II) units at the exterior. The optical activities of the helical arms were maintained after the cross-linking reaction. The Pd(II) units on the surface of the star polymer were chain extended with a new phenyl isocyanide bearing three hydrophilic triethylene glycol monomethyl chains, which afforded an amphiphilic star block copolymer carrying helical arms. Such a star block copolymer showed excellent thermoresponsiveness with the lower critical solution temperature (LCST) around 55 °C. This optically active and thermoresponsive star polymer can enantioselectively capture the S-enantiomer of racemic methyl benzyl alcohol solution at a temperature lower than the LCST and precipitated when the temperature was higher than the LCST, leaving the R-enantiomer in the solution. The enantiomeric excess (ee) of the isolated enantiomer is up to 75%.

中文翻译：

携带螺旋多异氰化物臂的光学活性和热响应星形嵌段共聚物的简便合成及其热触发手性分辨能力

制备了在每个末端带有降冰片烯单元和 Pd(II) 配合物的左旋螺旋聚苯异氰化物。降冰片烯末端通过开环复分解聚合 (ROMP) 与双降冰片烯接头进行核心交联，产生带有左旋螺旋臂的星形聚合物，其外部饰有 Pd(II) 单元。交联反应后，螺旋臂的光学活性得以保持。星形聚合物表面的 Pd(II) 单元用带有三个亲水性三甘醇单甲基链的新苯基异氰化物进行扩链，从而得到带有螺旋臂的两亲星形嵌段共聚物。这种星形嵌段共聚物表现出优异的热响应性，较低的临界溶解温度 (LCST) 约为 55 °C。外消旋甲基苯甲醇溶液的S-对映异构体在低于 LCST 的温度下，当温度高于 LCST 时沉淀，将R-对映异构体留在溶液中。分离的对映异构体的对映异构体过量 (ee) 高达 75%。

更新日期：2018-01-05

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