| Summary: | 碩士 === 國立交通大學 === 材料科學與工程系 === 91 === Synthesis and characterization of novel photoluminescent materials containing conjugated-rings with pyridine
and alkoxy-substituted lateral groups
Graduate student: Boon-Seng Ng Advisor:Dr. Hong-Cheu Lin
Department of Materials Science and Engineering
National Chiao Tung University
Abstract
A series of novel photoluminescent materials with conjugated aromatic segment including end-capping pyridine and substituted alkoxy group were synthesized successfully via Mcmurry, and Heck reaction. Hydrogen bonding complexes were obtained from the mixing of these photolumines -cent compounds with different proton donors containing carboxylic acids groups in THF/CH2Cl2. The thermal properties of these materials were measured by TGA. The decomposition temperature at 5% weight loss (Td) of all compounds ranged from 259℃~413℃. DSC and POM claimed that most of these compounds have no mesogenic phase except PBBPOC4-ONA and OBBPOC8-ONA. 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 388nm ~448nm in diluted CH2Cl2. They emitted blue-green to green fluorescence around 456~500nm in CH2Cl2. The quantum efficiency of them were ranged from 35%~70% comparing to coumarin 6. 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, the complexes whose contains 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 5.30 eV ~ 5.82 eV and 2.89 eV ~3.58 eV respectively. The polarization measurement showed the existence of the polarized light and the polarization ratio is about 1.43 .
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