Studies on Helicity Induction of Polymers and its Memory

聚合物螺旋诱导及其记忆研究

• 批准号: 12450371
• 负责人: YASHIMA Eiji
• 金额: $ 5.82万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450371/
• 关键词: Polyphenylacetylene; Helical Structure; Induced CD; Polymerization in water; Helicity Induction; Chirality Memory; Chirality Discrimination; Chiral Amplification; アミン

The synthesis of helical polymers with controlled helix-sense has aroused considerable interest in polymer chemistry in recent years because of their interesting structures and their possible applications in materials science. Recently, we found that macromolecular helicity with a predominantly one-handed helix can be induced in optically inactive poly(phenylacetylenes), for instance, poly((4-carboxyphenyl)acetylene) (PCPA) upon complexation with chiral amines in DMSO, thus exhibiting an induced circular dichroism (ICD) in the polymer main chain. Moreover, the induced helical structure was found to be memorized after replacement of the chiral amines by achiral amines. In this study, we investigated the mechanism of the helicity induction and the memory of helical chirality by means of IR, UV, and CD spectroscopies.We found that a one-handed helix is cooperatively induced on PCPA upon ion pair formation of the carboxy groups of PCPA with chiral amines. On the other hand, the free tons formation is essential for the macromolecular helicity memory of PCPA after the replacement of the chiral amines with achiral amines, since the intramolecular electrostatic repulsion between the neighboring carboxylate ions contributes to reduce the atropisomerization process of PCPA. On the basis of the solved mechanism, we found that the coexistence of the excess bulky, achiral amine with a small amount of chiral amine caused a dramatic increase in the ICD being comparable to the full ICD induced by excess chiral amine. The induced one-handed helical PCPA was further successfully memorized by achiral amines.A similar macromolecular helicity induction and the memory of the helical chirality was possible for an optically inactive polyisocyanide, so that this concept may be general and can be used as a promising method to construct novel, functional helical polymers with the desired pendant in a one-handed helical array.

近年来，具有受控螺旋方向的螺旋聚合物的合成因其有趣的结构及其在材料科学中的可能应用而引起了高分子化学的极大兴趣。最近，我们发现，在光学非活性聚（苯乙炔）中，例如聚（（4-羧基苯基）乙炔）（PCPA）与DMSO中的手性胺络合后，可以诱导出以单手螺旋为主的大分子螺旋性，从而表现出聚合物主链中的诱导圆二色性（ICD）。此外，发现在用非手性胺替换手性胺后，诱导的螺旋结构被记忆。在这项研究中，我们通过红外、紫外和圆二色光谱研究了螺旋性诱导和螺旋手性记忆的机制。我们发现，在羧基离子对形成时，PCPA上协同诱导了单手螺旋。 PCPA 与手性胺的反应。另一方面，用非手性胺取代手性胺后，自由吨的形成对于PCPA大分子螺旋记忆至关重要，因为相邻羧酸根离子之间的分子内静电斥力有助于减少PCPA的阻转异构化过程。在已解决的机制的基础上，我们发现过量的大体积非手性胺与少量手性胺的共存导致ICD的急剧增加，与过量手性胺引起的完全ICD相当。诱导的单手螺旋PCPA进一步被非手性胺成功记忆。对于光学非活性多异氰化物，类似的大分子螺旋诱导和螺旋手性记忆是可能的，因此这个概念可能是通用的并且可以用作一种有前途的方法以单手螺旋阵列构建具有所需悬垂物的新型功能性螺旋聚合物。