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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5906


    Title: 取代基效應對反式-4-(N-苯基)二苯乙烯胺之光化學行為影響之研究;Studies on the Substituent Effects on the Photochemical Behavior of trans-4-(N-Phenylamino)stilbenes
    Authors: 廖康廩;Kang-ling Liau
    Contributors: 化學研究所
    Keywords: 光化學行為;反式-4-(N-苯基)二苯乙烯胺;取代基效應;Substituent Effects;Photochemical Behavior;trans-4-(N-Phenylamino)stilbenes
    Date: 2002-06-24
    Issue Date: 2009-09-22 10:10:03 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本論文乃針對「胺基共軛效應」對反式-4-二苯乙烯胺光化學行為的影響,作更深入的探討。「胺基共軛效應」主要在探討反式-4-(N-苯基)二苯乙烯胺。由於N-苯基取代導致反式-4-二苯乙烯上胺的胺基構形趨於平面,使其在激發態電荷轉移能力增加,光異構化反應速率變慢,因而造成高螢光量子產率的特性。   為了瞭解取代基效應對反式-4-(N-苯基)二苯乙烯胺光化學行為的影響,我們以反式-4-胺基二苯乙烯為主體,設計了在N-苯基上含取代基的化合物2~6,以及在二苯乙烯4’位置上含強拉電子基的化合物7~8,並以化合物2與7為主軸,作一系列光化學性質的研究與比較。   化合物2在各種不同的溶劑中,會隨著取代基推電子性增加,其吸收光譜與螢光光譜有紅位移的現象。螢光的強弱則視溶劑與取代基的推拉電子性而定。在正己烷中,螢光隨著取代基的拉電子性增加而增強;在極性較高的溶劑中,螢光強弱與取代基的推拉電子性則無類似關係。當取代基是甲氧甲酯基與腈基時,可能有分子扭轉電荷轉移結構(TICT),使螢光量子產率下降。   此外,化合物7因同時含有強推與強拉電子基,其吸收光譜與螢光光譜隨著溶劑極性改變,有更明顯的紅位移的現象。在極性較高的溶劑中,可能因具有分子扭轉電荷轉移結構,其螢光與異構化量子產率比相同取代的反式-4-(N-苯基)二苯乙烯胺為低。 This thesis is a follow-up study on the “amino conjugation effect” of trans-4-aminostilbenes. N-phenyl substitution of trans-4-aminostilbene leads to a more planar ground-state geometry about the amino nitrogen atom, a larger charge-transfer character, a slower rate constant for photoisomerization, and thus a higher fluorescence quantum yield. To investigate the substituent effect on the photochemical behavior of trans-4-N-phenylaminostilbene, we have synthesized compound series 2-6, which have substituents on the N-phenylamino group, and compound series 7 and 8, which contain strong electron-withdrawing groups at the 4’ position of the stilbene group. More detained photochemical studies were performed on compound series 2 and 7. Electron-donating groups result in red-shifted absorption and emission spectra for compounds 2, which is valid in a variety of solvents. In hexane, the fluorescence quantum yield of compound 2 is larger for substituents with a stronger electron-withdrawing ability. Such a behavior is however not observed in other solvents. When the substituent in 2 is an ester or a cyano group, the fluorescence quantum yield is particular low in medium or polar solvents, which can be attributed to the formation of twisted internal charge-transfer (TICT) states. In the case of compounds 7, a significant solvent-dependent fluorescence spectra were recorded as a result of the presence of both strong electron-donating and electron-withdrawing groups. In polar solvents, both fluorescence and photoisomerization quantum yields are low, which might be a consequence of TICT formation.
    Appears in Collections:[化學研究所] 博碩士論文

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