Wang Qian, Chu Ben-Fa, Chu Jia-Hong, Liu Na, Wu Zong-Quan
Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, 230009 Anhui Province, China.
ACS Macro Lett. 2018 Feb 20;7(2):127-131. doi: 10.1021/acsmacrolett.7b00875. Epub 2018 Jan 5.
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 -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 -enantiomer in the solution. The enantiomeric excess (ee) of the isolated enantiomer is up to 75%.
制备了一种在每个末端带有降冰片烯单元和钯（II）配合物的左旋螺旋状聚（苯基异氰化物）。降冰片烯末端通过开环易位聚合（ROMP）与双降冰片烯连接体进行核心交联，得到一种星形聚合物，其左旋螺旋臂在外部装饰有钯（II）单元。交联反应后，螺旋臂的光学活性得以保持。星形聚合物表面的钯（II）单元与带有三条亲水性三甘醇单甲醚链的新型苯基异氰化物进行链延伸，得到一种带有螺旋臂的两亲性星形嵌段共聚物。这种星形嵌段共聚物在约55℃的较低临界溶液温度（LCST）下表现出优异的热响应性。这种具有光学活性和热响应性的星形聚合物在低于LCST的温度下能够对映选择性地捕获外消旋苄醇溶液的 - 对映体，并在温度高于LCST时沉淀，从而使 - 对映体留在溶液中。分离得到的对映体的对映体过量（ee）高达75%。
