Effects of substitution and terminal groups for liquid-crystallinity enhanced luminescence of disubstituted polyacetylenes carrying chromophoric terphenyl pendants  

作　　者：ZHOU Dan,CHEN YiWang,CHEN Lie,LI Fan,NIE HuaRong & YAO Kai Institute of Polymers/Department of Chemistry,Nanchang University,Nanchang 330031,China 

出　　处：《Science China Chemistry》2010年第6期1302-1315,共14页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China (50773029 & 50902067);the Natural Science Foundation of Jiangxi Province (2007GZC1727 & 2008GQH0046);Program for Innovative Research Team in University of Jiangxi Province

摘　　要：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 pre- pared 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 polyacety- lene parents,both CH3PA6OPr and CH3PA6CN showed a narrower energy gap.This demonstrated that the electrical con- ductivities of polyacetylenes could be enhanced by attaching appropriate pendants to the conjugated polyene backbones.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 pre- pared 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 polyacety- lene parents,both CH3PA6OPr and CH3PA6CN showed a narrower energy gap.This demonstrated that the electrical con- ductivities of polyacetylenes could be enhanced by attaching appropriate pendants to the conjugated polyene backbones.

关 键 词：DISUBSTITUTED POLYACETYLENES LIQUID crystallinity phase transition photoluminescence 

分 类 号：O621.25[理学—有机化学]