Abstract. Three ortho-, meta-, and para-linked polymers derived from 9,9-dioctylfluorene (FO) and dimethoxyl-biphenyl (DMBP) were designed and synthesized via catalyst-transfer Suzuki coupling polymerization with palladium(0) catalyst as initiator. Compared to PFO, the conjugated polymers of PFO-o-DMBP, PFO-m-DMBP, and PFO-p-DMBP displayed a significantly blued-shifted absorption and emission spectra with the change of the connecting site from ortho-, meta- to para-position, and the varying degrees were ascribed to the different types of steric hindrance of ortho-, meta-, and para-linkage, which partly hinder the intermonomer rotation of the polymer backbone, giving rise to molecular configuration from linear, zigzag to intertwined structure, and resulting in shortened conjugation length. The optical bandgap calculated from the onset of absorption spectra of the three polymers in solid film are all wider than that of the PFO, indicating that the incorporating of dimethoxyl-biphenyl increased the chain-twisting hindrance and influenced the molecular conformation of the copolymer. Systematical investigation of electrochemical and photophysical properties of the conjugated polymers suggests that the incorporation of dimethoxyl-biphenyl via ortho-, meta-, and para-linkage is an efficient and economic way to modify the properties of polyfluorenes.

中文翻译：

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通过在不同类型的连接位点掺入二甲氧基联苯来改变聚芴性能的策略

摘要。以钯(0) 催化剂为引发剂，通过催化剂转移Suzuki 偶联聚合设计并合成了源自9,9-二辛基芴(FO) 和二甲氧基联苯(DMBP) 的三种邻位、间位和对位连接聚合物。与 PFO 相比，PFO-o-DMBP、PFO-m-DMBP 和 PFO-p-DMBP 的共轭聚合物显示出明显的蓝移吸收和发射光谱，连接位点从邻位、间位到对位，不同程度归因于邻位、间位和对位键的不同类型的空间位阻，这部分阻碍了聚合物骨架的单体间旋转，导致分子构型从线性、锯齿形到交织结构，导致共轭长度缩短。从固体薄膜中三种聚合物的吸收光谱开始计算的光学带隙均比PFO宽，表明二甲氧基联苯的加入增加了链扭曲阻碍并影响了共聚物的分子构象。对共轭聚合物的电化学和光物理性质的系统研究表明，通过邻、间和对位连接引入二甲氧基联苯是一种有效且经济的改变聚芴性能的方法。