Helical sense selective polymerization of bulky aryl isocyanide possessing chiral ester or amide groups initiated by arylrhodium complexes
Helical sense selective polymerization of bulky aryl isocyanide possessing chiral ester or amide groups initiated by arylrhodium complexes
复制标题
DOI：
10.1021/ma061758r
复制
发表时间：
2006-09
期刊：
影响因子：
5.5
通讯作者：
K. Onitsuka;Tomoko Mori;Mari Yamamoto;F. Takei;Shigetoshi Takahashi
中科院分区：
文献类型：
--
作者：
K. Onitsuka;Tomoko Mori;Mari Yamamoto;F. Takei;Shigetoshi Takahashi
制备了体积较大的芳基异氰化物单体，在邻位上含有叔丁基，在对位上含有手性酯或酰胺基，用芳铑配合物进行聚合，得到了多分散性指数较窄的多异氰化物，收率较高。大的比旋和在347 nm处强烈的棉花效应表明所得聚合物在溶液中主要保持单手螺旋构象。热学性能随聚合度的增加而增加，并固定在聚合度大于70的区域。观察到手性单体的光学纯度与所得聚合物的螺旋选择性之间存在正非线性关系。螺旋选择性取决于手性酯基的结构，如烷基链的长度和手性碳中心的位置。
Bulky aryl isocyanide monomers possessing tert-butyl groups at the ortho position and chiral ester or amide groups at the para position were prepared and polymerized by arylrhodium complex to give polyisocyanides with narrow polydispersity indexes in good yields. The large specific rotation and the intense Cotton effect at 347 nm suggest that the resulting polymers maintained predominantly one-handed helical conformation in solution. The chiroptical properties were increased with an increase in the polymerization degree and were fixed in the region of the polymerization degree more than 70. A positive nonlinear relationship was observed between the optical purity of the chiral monomer and the helical sense selectivity of the resulting polymers. The helical sense selectivity depends on the structure of the chiral ester groups such as the length of the alkyl chain and the position of the chiral carbon center.