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

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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