Effects of substitution and terminal groups for liquid-crystallinity enhanced luminescence of disubstituted polyacetylenes carrying chromophoric terphenyl pendants
作者:Dan Zhou、YiWang Chen、Lie Chen、Fan Li、HuaRong Nie、Kai Yao
DOI:10.1007/s11426-010-3166-1
日期:2010.6
Liquid-crystalline and light-emitting poly(2-alkyne)s containing terphenyl cores with hexamethyleneoxy spacers, and cyano or n-propoxy tails −“[CH3C=C(CH2)6O-terphenyl-R]” n −, where R=CN, CH3PA6CN, R=OCH2CH2CH3, CH3PA6OPr, were synthesized. The effects of the substitution and terminal groups on the properties, especially the mesomorphic and optical properties of the polymers, were investigated. The disubstituted acetylene monomers (CH3A6CN, CH3A6OPr) were prepared through multistep reaction routes and were polymerized by WCl6-Ph4Sn in good yields (up to 82%). All the monomers and CH3PA6CN exhibited the enantiotropic SmA phase with a monolayer arrangement at elevated temperatures, whereas CH3PA6OPr formed a bilayer SmAd packing arrangement. Upon excitation at 330 nm, strong UV and blue emission peaks at 362 and 411 nm were observed in CH3PA6OPr and CH3PA6CN, respectively. The luminescent properties of CH3PA6CN and CH3PA6OPr have been improved by introducing the methyl substituted group, and the quantum yield of the polymer with cyano tail CH3PA6CN (Φ = 74%) was found to be higher than that of CH3PA6OPr (Φ = 60%). Compared to polyacetylene parents, both CH3PA6OPr and CH3PA6CN showed a narrower energy gap. This demonstrated that the electrical conductivities of polyacetylenes could be enhanced by attaching appropriate pendants to the conjugated polyene backbones.
含六甲ylene氧间隔基和氰基或n-丙氧基尾的特苯核心的液晶和发光聚(2-炔)("-[CH3C=C(CH2)6O-特苯基-R]n-",其中 R=CN,CH3PA6CN,R=OCH2CH2CH3,CH3PA6OPr)被合成。研究了取代基和末端基团对聚合物特性,特别是液晶和光学特性的影响。通过多步反应路线制备了二取代乙炔单体(CH3A6CN,CH3A6OPr),并通过 WCl6-Ph4Sn 聚合得到了良好的产率(高达 82%)。所有单体和 CH3PA6CN 在升高温度下表现出单层排列的反向 SmA 相,而 CH3PA6OPr 形成了双层 SmAd 堆积排列。在 330 nm 激发下,CH3PA6OPr 和 CH3PA6CN 分别观察到 362 和 411 nm 的强 UV 和蓝光发射峰。通过引入甲基取代基团,CH3PA6CN 和 CH3PA6OPr 的发光特性得到了改善,氰基尾聚合物 CH3PA6CN 的量子产率(Φ = 74%)被发现高于 CH3PA6OPr(Φ = 60%)。与聚乙炔母体相比,CH3PA6OPr 和 CH3PA6CN 都显示出更窄的能隙。这表明通过将适当的支链附着到共轭多烯骨架上,可以提高聚乙炔的电导率。