茚芴之共軛寡聚物的合成與性質研究

Abstract

本論文中我們合成了一系列的寡聚茚芴化合物，主要是經由Suzuki-Miyaura偶合反應，合成出高產率的中間體 p-phenylene diester。接著利用有機鋰試劑進行親核性加成反應，最後在酸性條件下進行分子內環化反應得到不同共軛長度的梯型材料InF3~InF5，且越長的π-共軛長度分子有越長的吸收及放光光譜。從x-ray光譜圖可以看出這系列寡聚茚芴化合物的骨架具有剛硬及共平面性，也呼應了其展現出的光物理性質。引入甲苯基於寡聚茚芴骨架外側可以有效造成立體阻隔，減少分子間的堆疊，使材料的熱穩定性較佳。一系列茚芴為主體的衍生物InF3~InF5都具有短的放光波長及大的能隙 (band gap)，將可以應用在有機電致發光元件中的主體材料 (host materials)，同時我們也藉由引入具有多電子性或不同構型的芳香基團到骨架中觀察其物理行為的變化。 利用類似的反應條件，我們可以引入萘環及苯駢[b]噻吩基團到共軛主軸上，合成新型共平面材料。 以咔唑 (Carbazole) 為主的寡聚物及高分子聚合物，因具有良好的電洞傳輸性質所以常利用在OLED之主層材料。也可以利用相似的合成途逕，將咔唑的核心帶入此類新型共平面分子。 我們可以很容易的經由合成，將先前的InF3進一步在其末端的2號及8號位置上先行溴化，再利用Pd催化反應接上雙芳香胺基團。這類的衍生物都具有相當好的熱穩定性及高的玻璃轉換溫度(Tg)，同時這樣的三芳香胺化合物展現出強的藍色螢光，最大的吸收波長在405nm，放光則在426 nm。我們將利用這樣的新型三芳香胺化合物作為藍光的發光層材料。

A series of indenofluorene derivatives were synthesized in good yields through a common intermediate. The key intermediate is a p-phenylene diester obtained by Suzuki-Miyaura coupling reaction. Addition of aryllithium followed by ring closure under acidic condition produced different conjugated lengths of ladder-type materials. The red-shifting optical properties can be rationalized by the increases of theπ-conjugation along the long molecular axis. Both the photophysical studies and X-ray structure analysis agree with the rigidity and coplanar nature of the indenofluorene backbone. The introduction of the tolyl groups as the peripheral substitutions is highly beneficial for the thermal and morphological stability. These kind of indenofluorene-based materials, InF3、InF4 and InF5, have short emission wavelength and large energy band gap which indicate a great potential as host materials for OLED applications. Arenes bearing with different electronic properties can be introduced as the constituted units of π-conjugation backbone to perform the physical properties modulation. The highly efficient and versatile synthetic strategies can be applied for synthesizing novel coplanar chromophores, for example, introduce new arenes such as naphthalene or benzothiophene boronic acid as the constituted units of the conjugated backbone. Carbazole–based conjugated oligomers and polymers are used as hole–transporting as well as host materials for organic light-emitting devices (OLEDs). Many research endeavors have been devoted to design carbazole derivatives for optoelectronic applications. The synthetic protocol mentioned above then was applied for the synthesis of coplanar chromophore containing with carbazole as a core structure. We used a facile synthetic route to a new series of indenofluorene derivatives with diarylamino groups at the terminal 2,8-positions. The synthesis was achieved by bromination of InF3 followed by Pd-catalyzed amination reaction in the presence of tri-t-butyl phosphine. These compounds exhibited high thermal stability and were found to be amorphous with high Tg. The triaryldiamines exhibit strong blue photoluminescence (PL). Both triaryldiamines had an absorption maximum at 405 nm and an emission maximum at 426 nm. We will apply these materials as blue-emitting materials for OLEDs.