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標題: | 合成吡咯喹啉衍生物及探討其激發態質子轉移的性質 Synthesis of Pyrroloquinoline derivatives and Investigation of their Excited-State Proton Transfer (ESPT) Properties |
作者: | Yu-Chiang Peng 彭宇強 |
指導教授: | 周必泰(Pi-Tai Chou) |
關鍵字: | 激發態質子轉移,吡咯,吡啶,芳香化,時間解析螢光光譜, ESPT,Pyrrole,Pyridine,Aromatization,time-resolved fluorescence experiments, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 本次研究內容是合成1H-pyrrolo[3,2-g]quinoline (PyrQ)及其衍生物,並且探討它的激發態質子轉移(Excited-state proton transfer, ESPT)光物理現象和動力學機制,在此之前,我們實驗室曾經有發表過幾篇文獻是關於7-azaindole (7AI)和7-aminoquinoline (7AQ),內容是對這兩個分子及它們衍生物的激發態質子轉移光譜現象的解釋和對他們光譜動力學的探討,而本次所研究的PyrQ是從這兩個分子衍生而來。在有機合成部分,我們以1,2,3,4-tetrahydroquinoline為起始物,藉由在其一邊建構五環吡咯(Pyrrole)並且將其六環吡啶(Pyridine)的部分芳香化(aromatization)得到我們的目標分子PyrQ,而他的衍生物可經由Vilsmeiere-Haack reaction在其3號位上引入甲醛(aldehyde)去做後續的衍生合成,最後得到在3號位引入甲醛基團(-CHO)和氰基團(-CN)的PyrQ衍生物,分別是3CHO-PyrQ和3CN-PyrQ。在光譜的部分,由於PyrQ的質子給予端和質子接受端距離遙遠,需透過溶劑的協助才能發生激發態質子轉移反應。在以甲醇當溶劑的放光光譜和時間解析螢光光譜可看到PyrQ及其衍生物都具有激發態質子轉移的特徵,並且從它們的螢光生命週期(lifetime)光譜中,可發現一個趨勢是當引入拉電子基在三號位上時,反而激發態質子轉移的速率變慢且拉電子能力越強,影響得更為明顯,其原因可從水中酸鹼滴定的實驗結果中推測出,因為拉電子基團的影響,雖然可使質子給予端酸性增加,但卻也影響吡咯環上氮的孤對電子,使其較難以共振效應傳電子至質子接受端,使其鹼性變弱。另外我們以7AI那篇文獻為參考,去推測PyrQ在激發態光譜動力學下的機制。
In this study, we strategically designed and synthesized 1H-pyrrolo[3,2-g]quinoline (PyrQ) and its derivatives to study their excited-state proton-transfer (ESPT) properties. PyrQ was synthesized from 1,2,3,4-tetrahydroquinoline by constructing the five-membered ring (pyrrole) and aromatization of six-membered-ring (Pyridine). In addition, 3CN-PyrQ and 3CHO-PyrQ, which are regarded as PyrQ derivatives, were obtained through modification of C(3) site via Vilsmeiere-Haack reaction. According to the steady-state spectrum and time-resolved fluorescence experiments, the results concluded that the PyrQs had ESPT properties, and that their proton transfer rate decreased in the order: PyrQ > 3CHO-PyrQ > 3CN-PyrQ, revealing that the more acidic proton donor, the slower the ESPT rate. The pH-titration experiment indicated that the R substituent influenced not only proton donor site but also proton acceptor site through resonance effect, implying that proton donation to acceptor site may represented as a key step in the process. Moreover, we proposed methanol-catalyzed ESPT mechanism, which established from our previous report, 7‑Azaindole (7AI) derivative. Upon excitation to give N* and then undergoing ESPT to generate T*, the rapid protonation takes place to result in the population of TC* on account of the larger pKa* of PyrQs than methanol molecules. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60027 |
DOI: | 10.6342/NTU202003260 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學系 |
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