光学活性聚硅烷的合成及其在手性识别中的应用研究

Optically active polysilanes are kind of polymer, which was constructed with Si-Si single bond. Theses polymers with controlled helical structures are useful as potential chiral selector for recognition, separation, and especially for applications in sensors, optical switches, and memory devices. Reductive dimerization of organochlorosilanes with alkali metals is a well-known method for the construction of the Si-Si linkage. However, under these rigorous reaction conditions, the substituent of synthesized polysilanes was limited to alkyl and aryl. In this project, low-valent samarium was used to investigate the polymerization of organodichlorosilanes. By applying this method, polysilanes with functional side groups (carboxyl) were prepared. The optically active polysianes were obtained by the interactions through hydrogen bonding between carboxyl functionalized polysilanes and chiral guests. The helicity of the optically active polysiane can be "memorized" when the amine is replaced by various ahiral amines. In this present research proposal, various novel optically active polysilanes will be constructed and their electronic properties, structure, fluorescent, circular dichroism (CD) and reactivity will be elucidated. The study will contribute not only to the development of basic organosilicon chemistry but also to providing the new carriers of optoelectronic functions in organic-inorganic hybrid materials in the near future.

光学活性聚硅烷是一类由Si-Si单键构筑成的新型聚合物。被认为是合成量子线（0.2 nm），光学电子开关和光记忆材料的理想有机高分子材料。目前，光学活性聚硅烷一般是通过碱金属还原二氯硅烷单体的方法制备，由于反应条件苛刻以及需制备复杂的手性二氯硅烷单体，使得聚硅烷的种类十分有限，尤其是无法制备官能团化的聚硅烷。为解决上述问题，本项目拟采用低价稀土金属催化氯硅烷的还原聚合反应制备羧基官能化的聚硅烷；然后以非手性聚硅烷为母体，利用聚硅烷上的螺旋转换点（羧基）与手性配体（客体）（手性醇、胺、氨基醇等）间的手性络合作用制备光学活性的聚硅烷。依据不同手性配体诱导的聚硅烷的螺向的差异，考察羧基官能团化聚硅烷在手性识别中的应用。借助紫外，荧光，圆二色谱等测试手段，研究这些聚合物的光谱特征及构象。同时在侧链基团，双阱势能和外部刺激的综合作用下，研究该类化合物作为光学开关和光存储材料的应用价值。

光学活性聚硅烷有着特殊的电子光谱、场致发光、导电性等其它碳系和硅氧系聚合物所没有的特定的物理、化学性质。在分子识别以及在高效气相或液相色谱中作为手性固定相材料等方面有着广泛的应用前景。项目根据计划书开展工作，研究发现手性胺，如鹰爪豆碱（-）-SP不仅能诱导聚硅烷手性的形成，而且能控制聚硅烷的螺向。在催化量的鹰爪豆碱（-）-SP（10mol%）作用下，利用丁基锂与聚甲基苯基硅烷的反应，生成的聚硅烷PS-5在352nm附近有较强的正卡滕效应（Cotton effect）。聚硅烷手性的产生来源于聚硅烷和丁基锂反应时手性胺的诱导。聚硅烷诱导圆二色谱（ICD）的强度与手性胺的用量成正比关系；同时，烷基锂碱性的强弱也影响ICD的强度。聚甲基苯基硅烷分别在丁基锂 （S）-2或者（R）-2作用下，生成的聚硅烷PS-9和PS-10在352nm左右都有较强的正好相反的卡滕效应（Cotton effect），二者互为镜像。这些工作为制备可实际应用的纳米线提供了理论依据。已发表研究论文3篇，申请国家发明专利3项，其中获得授权1项。