Helicity induction and memory of the macromolecular helicity in a polyacetylene bearing a biphenyl pendant.
Helicity induction and memory of the macromolecular helicity in a polyacetylene bearing a biphenyl pendant.
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DOI：
10.1002/asia.200700279
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发表时间：
2008-03
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影响因子：
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通讯作者：
Katsuhiro Maeda;S. Tamaki;Kazumi Tamura;E. Yashima
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文献类型：
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作者：
Katsuhiro Maeda;S. Tamaki;Kazumi Tamura;E. Yashima
以4 ′-乙氧羰基-4-联苯基乙炔为原料，在铑催化剂作用下进行聚合反应，然后水解酯基，合成了一种新型的侧链含羧基联苯基的顺反式聚苯乙炔（poly-1）。在二甲基亚砜（DMSO）中与各种手性胺和氨基醇络合后，聚合物在UV/维斯区域中表现出特征诱导圆二色性（ICD），这是由于聚合物主链的主要单手螺旋形成以及侧基联苯基团的过量的单手轴向扭曲构象。聚-1与（R）-2-氨基-1-丙醇复合显示出独特的大分子螺旋度的时间依赖性反转。此外，在DMSO中，用非手性的2-氨基乙醇或正丁胺取代手性胺后，由手性胺诱导的聚-1的优先手性螺旋构象被进一步“记忆”。与先前报道的聚（（4-羧基苯基）乙炔）的记忆形成鲜明对比，本螺旋记忆的聚-1是伴随着记忆的扭曲联苯手性的吊坠。前所未有的，螺旋记忆的聚-1与非手性2-氨基乙醇被发现同时发生反转的轴向手性的联苯基团，然后由记忆的反转联苯手性，从而显示出显着的变化，在CD光谱图案。
A novel, cis-transoidal poly-(phenylacetylene) bearing a carboxybiphenyl group as the pendant (poly-1) was prepared by polymerization of (4'-ethoxycarbonyl-4-biphenylyl)acetylene with a rhodium catalyst followed by hydrolysis of the ester groups. Upon complexation with various chiral amines and amino alcohols in dimethyl sulfoxide (DMSO), the polymer exhibited characteristic induced circular dichroism (ICD) in the UV/Vis region due to the predominantly one-handed helix formation of the polymer backbone as well as an excess of a single-handed, axially twisted conformation of the pendant biphenyl group. Poly-1 complexed with (R)-2-amino-1-propanol showed unique time-dependent inversion of the macromolecular helicity. Furthermore, the preferred-handed helical conformation of poly-1 induced by a chiral amine was further "memorized" after the chiral amine was replaced with achiral 2-aminoethanol or n-butylamine in DMSO. In sharp contrast to the previously reported memory in poly((4-carboxyphenyl)acetylene), the present helicity memory of poly-1 was accompanied by memory of the twisted biphenyl chirality in the pendants. Unprecedentedly, the helicity memory of poly-1 with achiral 2-aminoethanol was found to occur simultaneously with inversion of the axial chirality of the biphenyl groups followed by memory of the inverted biphenyl chirality, thus showing a significant change in the CD spectral pattern.