含雙吡啶及中心茀之五共軛芳香環螢光材料之研究

Abstract

含雙吡啶及中心茀之五共軛芳香環螢光材料之研究

學生：林意惠 指導教授：林宏洲 博士

國立交通大學材料科學與工程研究所 碩士班

摘要

本實驗主要是利用Heck Coupling Reaction、Wittig-Horner Reaction合成出一系列以雙鍵連結之五環共軛螢光材料；其核心結構為含兩個具有當質子受體特性的吡啶環。所有化合物經H1-NMR、C13-NMR 和元素分析加以鑑定其結構與純度，再與不同的質子予體酸製備成氫鍵錯合物。在熱性質方面，以熱重分析儀(TGA)得知熱裂解溫度(Td)為370℃~409℃。由熱微差掃瞄分析儀(DSC)與偏光顯微鏡(POM)觀察出合配製成的氫鍵錯合物中，皆顯現了向列型液晶的性質。化合物的螢光性質則由紫外光可見光光譜儀（UV-Vis）和螢光分光光譜儀測得，化合物在極稀(10-5 M)的THF溶劑中所得到的最大吸收波長範圍為405 nm~430 nm；最大螢光（PL）放射波長為455 nm ~480 nm，化合物都為發綠光材料，量子效率為60％∼67％。當配置氫鍵錯合物時所取用的酸pH值越強，越容易形成氫鍵錯合物，由於拉電子效應變強，分子LUMO變低，Energy Band Gap就變窄，所以酸度最強的THDA配成氫鍵錯合物後，其造成紅位移的現象最為明顯。循環伏安法(CV)測得不可逆氧化電位，得知本系列化合物HOMO位於5.29 eV ~ 5.58 eV。由於還原電位不明顯，經由λmax onset推算得知LUMO位於2.74 eV ~2.95 eV。在液晶性質和發光特性相結合的偏極化實驗中，成功發現共軛螢光分子在液晶相(配位後)中可發出具有方向性的偏極化光，且Polarization Ratio為4.89倍。

Study of Novel Photoluminescent Materials Containing Five-Conjugated Aromatic Rings with Bis-pyridyl Group and Fluorene central core

Graduate student : Yi-Hui Lin Advisor : Dr. Hong-Cheu Lin

Department of Materials Science and Engineering National Chiao Tung University

Abstract

A series of novel photoluminescent materials with five conjugated aromatic segment including end-capping pyridine were synthesized suc- cessfully via Heck coupling reaction, Wittig -Horner reaction. Hydrogen bonding complexes were obtained from the mixing of these luminescent compounds with different proton donors containing carboxylic acids gr- oups in THF. The thermal properties of these materials were measured by TGA. The decomposition temperature at 5% weight loss (Td) of all com- pounds ranged from 370℃~ 409℃. DSC and POM claimed that most of these compounds have mesogenic phase. The optical properties of these materials were measured by UV-Vis and PL (photoluminescence) spectroscopic studies. These compounds exhibited maximum absorption in the range of 405 nm~430 nm in diluted THF. They emitted green fluorescence around 455~480 nm in THF. The quantum efficiency of them were ranged from 60% ~ 67% comparing to Perylene. For a good formation of Hydrogen-bonding complexes, the highly acidic proton donor should be used . The energy band gap was shortened once the Hydrogen-bonding complexes were formed. According to the PL spectra, all the complexes whose contain THDA showing the most apparent red-shifted emission due to its lowest pka value. The CV showed that the HOMO and LUMO of these compounds were located at 5.29 eV ~ 5.58 eV and 2.74 eV ~ 2.95 eV respectively. The polarization measurement showed the existence of the polarized light and the polarization ratio is about 4.89 .