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標題: | 以五苯荑-吲哚衍生物為主體之分子煞車合成與性質研究 Synthesis and Characterization of Pentiptycene-Indole-Derived Molecular Brakes |
作者: | I-Tsun Lee 李依純 |
指導教授: | 楊吉水(Jye-Shane Yang) |
關鍵字: | 五苯荑,分子機械,分子煞車,吲,哚,核磁共振, pentiptycene,molecular machine,molecular brake,indole,NMR simulation, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本論文主要是合成與探討分子煞車系統IMe 與IAn,以五苯荑為轉子,吲哚
衍生物為分子煞車器,煞車器與轉子間以可進行順反式異構化之雙鍵連結,以期 應用於光電控制之分子機械元件設計。利用變溫1H 和13C NMR 圖譜、DFT 理論 計算,探討轉子於煞車前與煞車後之轉動動能與動力學參數。當化合物於順式結 構時(cis-IMe ,cis-IAn),煞車器與轉子間由於立體障礙因素,使轉子之單鍵 旋轉速率較慢(煞車開啓),而當化合物於反式結構時(trans-IMe,trans-IAn) 煞車器與轉子間則因無明顯立體障礙,使轉子有較快的旋轉速率(煞車關閉), 轉子於煞車開啓與關閉狀態間旋轉速率差可達108 倍。 此分子煞車系統之控制,則是利用煞車器與轉子間連接之雙鍵,在二氯甲烷 溶劑中之順反異構化進行煞車轉換。以反式化合物(trans-IMe,trans-IAn)為起 始物,利用大於370 奈米波長為激發光源,當達到光反應穩定狀態時,反式異構 物轉換為順式異構物之效率可達90%以上,此乃由於化合物於反式結構時於370 奈米波長之吸收度較大,因此可有效率被激發至激發態,進而進行異構化反應。 同樣,順式異構物可經由激發290 奈米波長,轉換回反式異構物,當達到光反應 穩定狀態時,兩者比例約為55:45 (順式:反式),由於吸收光譜之重疊性,使 得順式異構物利用光為能源時,轉換為反式異構物之效率較差。另一方面,若使 用電化學氧化方式,將順式異構物經由陽離子自由基中間體,轉換為反式異構物 之單次轉換效率則可達72%,但由於化合物對於電化學實驗之低穩定性, 使其無 法成為一理想光電轉換之分子煞車系統。 We designed pentiptycene-indole-derived molecular brakes IMe and IAn for the purpose of achieving both high switching efficiency and efficient brake performance. Rotational rate and kinetic parameters were deduced form variable-temperature 1H and 13C NMR simulation and DFT calculation. The rotational rate could reach 108 -folded difference between brake on and brake off states. We compared 2 different energy input, light and electric energy, for isomerization switch of the compounds. For photoisomerization switch, the efficiency could reach > 90% from trans isomers to corresponding cis isomers when the compound was irradiated with > 370 nm light. The high switching efficiency was because of the larger absorbance for trans isomers at the wavelength. However, the photoisomerization switching efficiency was only 45% for cis isomers to corresponding trans isomers for their overlapping absorption spectra. On the other hand, the electrochemical isomerization switch could reach 72% efficiency from cis-IMe to thermodynamically stable trans-IMe through a cation radical intermediate. However, because of the instability of indole moiety upon electric pulse, the pentiptycene-indole-derived molecular brakes are not ideal systems with electric energy input. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/65642 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學系 |
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