以三芴為放光主體離子感測器之合成與應用

Abstract

本篇論文研究內容主要設計以三芴（terfluorene）為主體，在芴的9號位置銜接上不同的冠醚（crown ether）官能基，希望藉由三芴的高螢光量子效率及高載子移動率，和冠醚對離子的選擇性及高離子傳導特性，而開發出新型的離子感測器TA6及光電材料TB5和T3B5。 在離子測測器方面，我們以phenyl-1-aza-18-crown-6為辨示端而合成出TA6，利用光激發電子轉移（photoinduced electron transfer）而造成螢光的增減，發現其對Fe2+，Pb2+及Hg2+具良好的選擇性，其螢光約增強四十倍。利用Job’s method、Benesi-Hildebrand method及ESI-Mass圖譜，發現其基態結合比例為1：1。 另一方面，我們結合三芴與具離子傳導特性的benzocrown ether，而合成出TB4、TB5、TB6及T3B5，並以TB5及T3B5做成LECs（Light-emitting Electrochemical Cells）元件，發現其EQE（external quantum efficiency）分別為0.25 %及0.56 %，而加入適量的NaPF6使化合物T3B5形成錯合物，可提升元件的效率到0.63 %，並延長元件的壽命達2.2倍。

A series of novel materials which contain terfluorene as a backbone and crown ether(s) as pendant substitution(s) have been synthesized in this thesis. The structures of these materials are shown as below: The crown ether is capable of binding to various cations, allowing these new materials to serve as ion-selective chemosensors. The terfluorene derivatives incorporated with aza-18-crown-6 (TA6) have weak fluorescence due to photoinduced electron transfer (PET) process. After treating TA6 with various cations, the PET process was strongly blocked, leading to a distinct change in fluorescence emission (from weak green to strong blue). From titration experiments, TA6 was found to have excellent selectivity to Hg(Ⅱ), Pb(Ⅱ), and Fe(Ⅱ). The fluorescence intensity enhanced 40-folds after treating with these three cations. This study shows that TA6 can be a prototype of sensor for sensing toxic cation such as Hg(Ⅱ) and Pb(Ⅱ) in biosystem and environment. The bifunctional materials which have terfluorene for charge carriers transporting and crown ether for ions transporting can be applied in light-emitting electrochemical devices. The LEC (Light-emitting Electrochemical Cell) devices were fabricated by spin coating of the terfluorene derivatives and electrolytes. The EQE (external quantum efficiency) of TB5 and T3B5 devices can reach up to 0.25 % and 0.56 %, respectively. By adding appropriate amount of NaPF6 to the thin films of T3B5, the device shows higher efficiency (0.63 %) and longer lifetime.