Supermolecular Ladder Chiral Double Helical Polymer by Helix-sense-selective Polymerization Controlled by Achiral Values

本研究项目的研究人员发现，当具有大量手性取代基的苯乙炔被聚合时，主链上存在诱导手性。我们认为这种手性结构不包含不对称中心，仅由单手螺旋构象引起。但由于该手性聚合物含有两种手性结构，因此无法确定其识别能力和手性主链本身的精确结构。为了澄清这一点，我们利用非手性单体与手性催化体系进行螺旋选择性聚合，合成了一种不含任何其他手性基团的手性螺旋型聚苯乙炔。此外，我们发现螺旋感不仅可以通过改变手性量来控制，也可以通过改变非手性量来控制。所得聚合物的手性主链由分子内氢键维持，具有超分子阶梯型手性双螺旋聚合物结构。因此，当极性溶剂加入后，主链手性消失。在这项研究中，我们对新的合成方法和通过该方法得到的新聚合物进行了进一步的研究。(1)螺旋-选择性聚合的推广(2)螺旋-选择性聚合机理的探讨(3)超分子阶梯手性双螺旋聚合物新功能的开发(4)超分子阶梯手性双螺旋聚合物分子结构的讨论

The investigators of this research project found an induced chirality in the main chain when a phenylacetylene having a bulky chiral substituent was polymerized. We thought this chiral structure did not contain asymmetric centers and was caused only by one-handed helical conformation. However, this chiral polymer contained two kinds of chiral structures and therefore the recognition ability and the precise structure of the chiral main chain itself could not be confirmed.To clarify it we realized synthesis of a chiral helical polyphenylacetylene which does not have any other chiral moieties by helix-sense-selective polymerization of an achiral monomer with a chiral catalytic system. In addition, we found the helix sense can be controlled by changing not only chiral amounts but also achiral amounts. And the chiral main-chain of the resulting polymer was found to be maintained by intramolecular hydrogen bonds, i.e., this polymer has a supermolecular ladder chiral double helical polymer structure. Therefore this main chain chirality disappeared when a polar solvent was added.In this study, we studied further the following points on the new synthetic method and the new polymer obtained by the method.(1) Generalization of the helix-sense-selective polymerization(2) Discussion of the mechanism of the helix-sense-selective polymerization(3) Development of new functions of the supermolecular ladder chiral double helical polymer(4) Discussion of the molecular structure of the supermolecular ladder chiral double helical polymer