Polypseudorotaxane Constructed from Pillar[5]arene and Viologen Polymer
Polypseudorotaxane Constructed from Pillar[5]arene and Viologen Polymer
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DOI：
10.1021/ma100079g
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发表时间：
2010-04-13
期刊：
影响因子：
5.5
通讯作者：
Nakamoto, Yoshiaki
中科院分区：
文献类型：
--
作者：
Ogoshi, Tomoki;Nishida, Yoko;Nakamoto, Yoshiaki
介绍。通过共价聚合物与大环分子络合构建的聚拟轮烷和聚轮烷由于大环环可以自由移动并绕聚合物轴旋转而引起了超分子、材料和生物医学化学领域的极大兴趣。 1 为了构建聚拟轮烷和聚轮烷，最初使用环糊精2r4 和冠醚5 作为大环组分。原田等人。首先报道了由环糊精和线性聚合物如聚乙二醇和聚丙二醇组成的聚拟轮烷的形成。 2 由于线性聚合物链和环糊精内腔之间的疏水相互作用，环糊精分子在水中自发地连接到聚合物链上。此外，通过在聚拟轮烷中添加庞大的封端基团，成功合成了环糊精基聚轮烷。 3 由于葫芦脲还可以在水介质中与带正电的分子形成非常稳定的主客体复合物，因此制备了由葫芦脲和带正电的聚合物组成的聚拟轮烷和聚轮烷。 6我们最近合成了一种新型主体分子，并将其命名为“支柱[5]芳烃”（图1a）。 7, 8 柱[5]芳烃的组成与典型的杯芳烃几乎相同。 9 然而，由于其重复单元在对位通过亚甲基桥连接，柱[5]芳烃具有独特的对称柱结构，与间位桥联杯芳烃的篮状结构不同。由于柱[5]芳烃由对苯二酚的电子供体组成，因此它与紫精和吡啶鎓衍生物等电子接受分子表现出非常有趣的主客体特性。 7 因此，在本通讯中，我们报告了一种新型聚拟轮烷，其由支柱 [5] 芳烃作为环和紫罗碱聚合物作为聚合链构建（图 1b）。我们研究了紫罗碱部分之间的端基和连接体长度对紫罗碱聚合物与柱[5]芳烃络合的影响。此外，还报道了柱[5]芳烃沿聚合物轴的有趣的溶剂依赖性穿梭行为。
Introduction. Polypseudorotaxanes and polyrotaxanes constructed through complexation of covalent polymers with macrocyclic molecules have attracted tremendous interest in the fields of supramolecular, material and biomedical chemistry because the macrocyclic rings move freely and rotate on the polymer axis. 1 For construction of polypseudorotaxanes and polyrotaxanes, cyclodextrins2r4 and crown ethers5 were initially utilized as the macrocyclic components. Harada et al. first reported the formation of polypseudorotaxanes consisting of cyclodextrins and linear polymers such as poly (ethylene glycol) and poly (propylene glycol). 2 Cyclodextrin molecules are spontaneously threaded onto the polymer chain in water due to hydrophobic interactions between the linear polymer chain and the inner cavity of the cyclodextrin. Moreover, by addition of bulky end-capping groups to the polypseudorotaxanes, cyclodextrin-based polyrotaxanes were successfully synthesized. 3 Since cucurbiturils can also form very stable hostrguest complexes with positively charged molecules in aqueous media, polypseudorotaxanes and polyrotaxanes consisting of cucurbiturils and positively charged polymers have been prepared. 6We recently synthesized a new type of host molecule and named it “pillar [5] arene”(Figure 1a). 7, 8 The composition of pillar [5] arene is almost the same as that of typical calixarenes. 9 However, because its repeating units are connected by methylene bridges at the para-position, pillar [5] arene has a unique symmetrical pillar architecture, which is different from the basketshaped structure of the meta-bridged calixarenes. Since pillar [5] arene is composed of an electron donor of hydroquinone, it exhibits very interesting hostrguest properties with electron accepting molecules such as viologen and pyridinium derivatives. 7 Therefore, in the present communication we report a novel polypseudorotaxane constructed from pillar [5] arene as the cyclic rings and viologen polymer as the polymeric chain (Figure 1b). We investigated the effects of the end-group and the length of the linker between the viologen moieties on complexation of the viologen polymers with pillar-[5] arene. Moreover, intriguing solvent-dependent shuttling behavior of pillar [5] arene along the polymer axis is reported.