POLAR INTERACTION-INDUCED NEW PHYSICAL PROPERTIES OF POLYSILANES

具有通式{R-Si-R ′}_n的极性聚硅烷，其中R和/或R ′表示烷基、芳基或醚基，例如-（CH_2）_3-O-（CH_2CH_2O）_m-R，m=0-3，-（CH_2）_3-O-Ph，-（CH_2）_4-O-C_3H_7，（CH_2）_5-O-C_2H_5，和-（CH_2）_6-O-CH_3，通过相应的二氯硅烷的Wutz型偶联反应制备。大部分聚硅烷在极性溶剂如THF、CH_3CN和醇中溶解。具有低聚醚侧基的聚硅烷被发现是水溶性的，并且与极性溶剂以及离子物种显示出不同的极性相互作用。聚硅烷[CH_3-Si-（CH_2）_3-O-（CH_2CH_2O）_m-R（m=0-3）]的第一种溶剂化变色现象是随着溶剂极性的降低而发生连续的红移。当聚（双（4-丙氧基丁基）硅烷和类似物与六氟-2-丙醇形成强氢键时，也发现了不寻常的不连续型溶剂化变色。聚硅烷中的极性侧基与LiClO_4在固态下形成离子络合物。这些配合物的热致变色行为与Li/Si比密切相关，当Li/Si比较小时，化合物的热致变色行为发生红移，当Li/Si比大于4时，化合物的热致变色行为发生蓝移。将上述极性聚硅烷的热致变色行为与氢键诱导的溶剂化变色行为进行了比较，发现这些极性相互作用诱导的变色行为之间没有直接的相似性。作为研究的延伸，发现了许多聚二烷基硅烷具有一种新的冷却速率依赖的热致变色性。

Polar polysilanes with general formula of {R-Si-R'}_n, where R and/or R' represents alkyl, aryl or ethereal groups such as -(CH_2)_3-O-(CH_2CH_2O)_m-R, m=0-3, -(CH_2)_3-O-Ph, -(CH_2)_4-O-C_3H_7, (CH_2)_5-O-C_2H_5, and -(CH_2)_6-O-CH_3, were prepared by wutz-type coupling reaction of the corresponding dichlorosilanes. Most of the prepared polysilanes became soluble in polar solvents such as THF, CH_3CN and alcohols. Polysilanes with oligo-ethereal side groups were found to be water-soluble and show diverse polar interaction with polar solvents as well as ionic species. The first solvatochromism was observed for polysilanes of [CH_3-Si-(CH_2)_3-O-(CH_2CH_2O)_m-R (m=0-3) ; they show continuous red shift by decreasing the polarity of solvent. Unusual discontinuous type of solvatochromism was also found for poly(bis(4-propoxybutyl) silane and analogues when they make strong hydrogen bonding with hexafluoro-2-propanol. The polar side groups in the polysilanes were found to yield ionic complex with LiClO_4 in the solid state. Thermochromic behavior of theses complexes was highly dependent on the ratio of Li/Si ; red-shift was induced on cooling when the Li/Si was small while blue-shift was induced when the ratio was >4. Thermochromic behavior of the above polar polysilanes were compared with the hydrogen bond induced solvatochromism and found that there were no direct similarity between these polar-interaction induced chromotropisms. As the extension of the research, a new cooling rate dependent thermochromism was found for many polydialkylsilanes.