Synthesis of Helical Polyacetylene and Construction of Molecular Solenoid

螺旋聚乙炔是近年来发展起来的一种新型的电磁和光学材料。最近，我们首次在手性双折射反应场中合成了具有左右旋结构的螺旋聚乙炔薄膜。在这里，我们通过开发以下方法扩展了螺旋聚乙炔的合成。(1)新型手性钛配合物作为手性掺杂剂对合成螺旋聚乙炔具有催化活性：我们合成了一系列以手性中心基团或轴向手性1，1 '-联萘酮为配体的手性钛配合物，以开发适合乙炔不对称聚合的催化活性手性掺杂剂。研究发现，这些配合物在两种手性液晶的混合物中均能诱导出手性双（N^*）相，并在N^* 液晶下，以Et_3Al为助催化剂，能将乙炔分解为螺旋状聚乙炔。(2)垂直取向螺旋状聚乙炔薄膜在垂直向列手性液晶中的合成：我们构建了一个新的垂直向列N^* LC反应场，用于垂直取向螺旋状聚乙炔薄膜的合成。通过将手性掺杂剂（R）-或（S）-PCH 506-二醇和（R）-或（S）-PCH 308 ^* 添加到由PCH 506+（PCH 30））_26、PCH 506+（PCH 50））_26和PCH 506+（PCH 50）_28组成的垂直排列的NH3 * LC中来制备垂直排列的NH3 * LC。扫描电子显微镜（SEM）的测量结果表明，扭曲的聚乙炔原纤生长平行于膜厚度的方向，垂直排列的螺旋原纤形态。

Helical polyacetylene recently developed is anticipated to show novel electromagnetic and optical properties. Recently we synthesized for the first time helical polyacetylene films with left- and right-handed screw structures under chiral nematic reaction field. Here, we extended the synthesis of helical polyacetylene by developing the following approaches shown below.(1) Novel chiral titanium complexes as chiral dopants with catalytic activity for synthesis of helical polyacetylene : We synthesized a series of chiral titanium complexes with chiral center-containing groups or axially chiral 1,1'-binaphthyl ones as coordination ligands, to develop catalytically active chiral dopants feasible for the asymmetric polymerization of acetylene. It is found that these complexes induce chiral nematic (N^*) phase when dissolved in a mixture of two nematic liquid crystals (LCs) and can polymerize acetylene to give helical polyacetylene with an aid of Et_3Al used as a co-catalyst under the N^* LC.(2) Synthesis of Vertically Aligned Helical Polyacetylene Films in Homeotropic Chiral Nematic Liquid Crystals : We constructed a novel homeotropic N^* LC reaction field for synthesis of vertically aligned helical PA film. The homeotropic N^* LC was prepared by adding chiral dopant, (R)- or (S)-PCH506-binol and (R)- or (S)-PCH308^* into the homeotropic nematic LCs consisting of PCH506 + (PCH30))_26, PCH506 + (PCH50))_26, and PCH506 + (PCH50)_28. Scanning electron microscope (SEM) measurements showed twisted polyacetylene fibrils are grown parallel to the direction of film thickness, giving vertically aligned helical fibrillar morphology.