| 摘要: | 本論文成功合成出三系列之紅光與紅外光模型分子，第一系列為含有吡啶并吡嗪(pyrido pyrazine) 結構單元之對稱型分子；第二系列為含有噻吩并吡嗪(thieno pyrazine) 結構單元之四個對稱型分子，此系列為在噻吩并吡嗪不同位置上接推電子基團與否之組合；第三系列為含有吡喃(pyran) 結構單元之三個對稱型分子。利用吸收光譜儀可測得其最大吸收波長，再以此波長激發分子測得其螢光放射波長，可藉由結構的不同探討其紅移或藍移可能發生的原因，不同結構造成的非線性光學性質亦有所不同。非線性光學實驗則利用飛秒脈衝式雷射來激發模型分子，測得其螢光強度與入射光強度之平方成正比，以實驗證明為雙光子吸收之螢光，經由螢光比較法，可測得模型分子之雙光子激發截面積，由量測結果與結構討論歸納出以下結論：
[1]本論文分三系列共8個紅光或近紅外光雙光子染料，compound A (2PyQ-BTD)在甲苯溶劑下雖然有不錯的量子產率(74.85%)與很寬廣的雙光子吸收範圍，從730nm至960nm之雙光子截面值都有2000 GM左右，但螢光放射波長並無法達到預期的紅外光區，因此設計了第二系列之模型分子。
[2]第二系列以噻吩并吡嗪作為中心，並在(2,3)及(5,7)位上以單鍵接上推電子基團與否衍生出四個對稱型分子，其螢光放射波長皆位於近紅外光區。在噻吩并吡嗪之(5,7)位上有接推電子基團之模型分子，相比在(2,3) 位上接推電子基團之模型分子，螢光放射波長較紅移，並也具有較高的雙光子激發截面值。
[3]第三系列以吡喃做為中心結構，設計3個條型對稱型分子。其中在pyran上官能基改變，其光學性質並無顯著差異；再引入噻吩作為共軛系統的橋樑，螢光放射波長紅移，但雙光子激發截面值卻下降一些。
[4]本論文之compound B((2,3,5,7)4DFL-TQ)與compound H(2DFL-Tp-Pyran-2CN)之螢光放射波長分別在甲苯及THF溶劑下最紅移，並位於近紅外光區(650-1700 nm)，同時具有良好的雙光子吸收能力，在生醫顯影之領域有很好的應用潛能。
;Three series of model stuctures are designed and synthesized in order to construct chromophores that possess either red or near infrared (near-IR) emission. We have used various heterocyclic units including pyridopyrazine, thienopyrazine and pyran as the major building units for these model compounds. We have tried to tune the molecular structures within each series of these model chromophore and intended to investigate the relationship between structure and optical properties. After a series of linear and nonlinear optical property measurements, some structure-optical property relationship can be drawn as follows:
(1) We have successfully designed and synthesized red or near-IR chromophores. Compound A (2PyQ-BTD) has good quantum yield with 74.85% and wide two-photon absorption band. But its fluorescence turns out not in near-infrared region, so we designed the second series of model compound.
(2) All of the four molecules in the second series possess emission band within near-infrared region. Introducing electron donor at (5,7) position makes emission more red-shifted than that attaching electron donor at (2,3) position of thieno pyrazine, and better two-photon absorption absorptivity as well.
(3) Third series have three molecules using pyran as the central core. It is found that changing electron-withdrawing functional groups doesn’t affect much on its optical properties, but introducing thiophene as a part ofπ-bridge can red shift emission and exhibit a slightly lower two-photon absorptivity .
(4) In this work, compound B((2,3,5,7)4DFL-TQ) and compound H(2DFL-Tp-Pyran-2CN) have fluorescence emission in near-infrared region, and excellent two-photon absorption absorptivity as well. These two compounds have great potential in bioimaging. |
