AN ABRUPT SOLVATOCHROMIC TRANSITION IN A POLAR POLYSILANE
AN ABRUPT SOLVATOCHROMIC TRANSITION IN A POLAR POLYSILANE
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极性聚硅烷中的突然溶剂致变色转变
DOI：
10.1021/ja963724c
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发表时间：
1997
影响因子：
15
通讯作者：
R. West
中科院分区：
文献类型：
--
作者：
K. Oka;Naofumi Fujiue;T. Dohmaru;C. Yuan;R. West
我们观察到聚合物聚[双(4-丙氧基丁基)硅烯](PPBS)在苯或氯仿溶液中发生了突然的溶剂变色转变。当加入少量的1，1，1，3，3，3-六氟-2-丙醇时，PPBS的紫外光谱中325 nm处的吸收峰被348 nm处的吸收峰所取代。这种前所未有的行为可能是由于氟醇与聚合物侧链上的氧原子发生氢键作用，导致构象突变。聚硅烷聚合物在近紫外区显示出强烈的电子吸收带，归属为σfσ*跃迁。1许多聚硅烷表现出明显的这种紫外线吸收的热致变色性，这是由于聚合物构象随温度变化而改变了σ-共轭。2其他类型的变色行为对于聚硅烷来说不太常见，尽管已经报道了电致变色和压致变色4的孤立例子。溶致变色性是吸收光谱与溶剂性质的关系，对于聚乙炔5和聚噻吩6家族中的π共轭聚合物是已知的，但在聚硅烷中，溶剂变色仅在具有两个吸收峰的聚[双(对烷氧基苯基)硅烯]7中被报道，在极性溶剂中，较长的波长变得更加强烈。
We have observed a sudden solvatochromic transition in benzene or chloroform solutions of the polymer poly [bis (4-propoxybutyl) silylene](PPBS). The absorption band at 325 nm in the UV spectrum of PPBS is replaced by an absorption at 348 nm when small amounts of 1, 1, 1, 3, 3, 3-hexafluoro-2-propanol are added. This unprecedented behavior may result from hydrogen bonding of the fluoroalcohol to the oxygen atom in the polymer side chains, inducing an abrupt conformational transition.Polysilane polymers display strong electronic absorption bands in the near-ultraviolet region, assigned to σ f σ* transitions. 1 Many polysilanes exhibit marked thermochromism of this UV absorption, resulting from temperature-dependent changes in the polymer conformation that alter the σ-conjugation. 2 Other types of chromotropic behavior are less common for polysilanes, although electrochromism3 and piezochromism4 have been reported for isolated examples. Solvatochromism, the dependence of the absorption spectrum upon the nature of the solvent, is known for π-conjugated polymers in the polyacetylene5 and polythiophene6 families, but among polysilanes solvatochromism has been reported only for poly-[bis (p-alkoxyphenyl) silenes], 7 which have two absorption maxima, the longer-wavelength band becoming more intense in polar solvents.