五苯荑衍生之共軛高分子之合成與性質研究

Abstract

五苯荑分子乃是由兩個雙環[2.2.2]辛烷作為架橋把五個苯環相連而成的分子，其巨大且剛硬的三維結構與分子內自由空間，於共軛高分子中有著特殊的運用。由於缺乏合適的五苯荑單體，目前的相關研究皆偏重於聚苯乙炔系統。經由多年的開發，我們實驗室成功合成出中央苯環具有兩個溴的雙溴五苯荑，利用不同的有機金屬偶合反應，可以合成出各式各樣的共軛高分子系統。本論文的工作主要為嘗試改善雙溴五苯荑的合成，並合成於主鏈中含有五苯荑結構的聚苯乙烯、聚茀及全為五苯荑的聚苯乙炔。相對於常見的聚苯乙烯及聚茀，導入五苯荑結構後的共軛高分子之最大吸收與螢光波長皆有50 nm左右的藍位移現象；而全為五苯荑的聚苯乙炔由於幫助溶解的長碳鏈以hyperconjugation的方式和主鏈溝通，造成分子內電荷轉移的現象。

Pentiptycene, a molecule with five benzene rings fused together through two bicyclo[2,2,2,]octane moieties, is a interesting building block in materials chemistry because of its rigid three dimensional structure as well as internal free volume. In past, pentiptycene-derived conjugated polymers are limited to poly(phenyleneethynylene) (PPE) systems because of the absence of suitable building blocks for making different polymer backbones. After years of searching, we have successfully synthesized dibromopentiptycene, which allows use to prepare a variety of pentitpycene-incoporated conjugated polymers, including poly(phenylenevinylene) (PPV), polyfluorene (PF) and all-pentiptycene PPE by using different kinds of organometallic coupling reactions. Compared to common PPVs and PFs, the pentitpycene-incoporated PEN-PPV and PEN-PF undergo blue shifts by about 50 nm in both absorption and fluorescence spectra. The all-pentiptycene PEN-PPE shows intramolecular charge transfer character, presumably due to the dialkoxy substituted phenylene rings functioning as electron donors through hyperconjugation interactions.