- 學位論文
鹵素取代之咪唑-吲哚衍生物：合成、光物理性質及其螢光感測研究
Studies of the Synthesis, Photophysical Properties and Fluorescent Sensing Behaviors of Halogen-substituted Imidazole–indole Derivatives
摘要
有機螢光分子由於其多項優點高靈敏度、高可調性、色彩豐富及靈活的分子設計，利用其受到外來物質刺激後分子構型、螢光範圍及顏色改變等特性，廣泛運用在多種螢光感測中。 我們設計並合成咪唑-吲哚衍生物，通過在吲哚端引入鹵素氟(F)、氯(Cl)與溴(Br)取代，以氫(H)取代作為比較鹵素前後差異，合成一系列含鹵素的咪唑-吲哚衍生物之D-π-A螢光分子，其中4,5-二苯基咪唑端作為電子供體(Donor，D)、乙烯基作為橋連(π)、吲哚端作為電子受體(Accepter，A)。 將咪唑-吲哚衍生物分為三個部分探討。第一個部分為研究鹵素取代對螢光分子的溶劑影響，鹵素做為拉電子基引入促使分子電荷轉移，螢光波長紅移，值得注意的是咪唑-吲哚衍生物在水、甲醇中發現具反溶劑效應，認為分子為極性較高的鹽類分子所造成。第二部分為順反異構物研究，烯鍵作為分子開關，經過光與熱的刺激後分子切換，選用溶劑二甲基亞碸方便以核磁共振分子追蹤，除了分子皆有可逆的優點外，鹵素分子具影響分子切換螢光顯色與分子切換的恢復能力。第三部份是分子開環/閉環研究，透過吲哚端上的酸基，結合開環與閉環共軛分裂造成顏色改變與鹵素取代小分子自組裝的特性，酸性及中性時分子為開環狀態呈強螢光，但在鹼性條件下分子為閉環螢光消失，另外在酸性條件Cl與Br取代的螢光分子，鹵素提供自組裝過程的偶極-偶極作用力，可以在低濃度下自組裝形成水凝膠，為了提高咪唑-吲哚衍生物的實用性，以L929細胞測試 (細胞存活度90%以上)，證實其具有好的生物相容性，以利往後在生物方面的發展。 鹵素取代基的引入影響咪唑-吲哚衍生物的螢光性質及自組裝性質，同時材料具有生物相容性，未來將有機會運用在光學元件、生物顯影的應用。
並列摘要
Organic fluorescent molecules have many advantages, such as high sensitivity, high tunability, colourful, flexible molecular design and fluorescence colour change by stimulation from the outside, they are widely used in various fluorescence sensing. In this work, we design and synthesis of imidazole-indole derivatives, in which the 4,5-diphenylimidazole moiety is used as the electron donor (Donor, D), the vinyl group is used as the bridge (π), and the indole is employed as the electron acceptor (Accepter, A). Through the introduction of halogen atoms of fluorine (F), chlorine (Cl) and bromine (Br) in D--A molecules, we investigate the effect of the halogen atom on the photophysical properties and self-assembly. The imidazole-indole derivatives are discussed in three parts. The first part is to study the influence of halogen substitution and the solvent on fluorescent properties. The halogen atom is an electron withdrawing group that can enhance the intramolecular charge transfer, and result in the red-shift of the fluorescence emission wavelength. It is worth noting that imidazole-indole derivatives exhibit anti-solvent effects in solvents because they are salt molecules with high polarity. The second part is the study of cis-trans isomerization of imidazole-indole derivatives induced by light irradiation and heating. We proved that halogen atoms can be incorporated to fine-tune the fluorescent properties and reversible switching characteristics in dimethyl sulfoxide. The third part is the investigation of molecular ring opening/closing. The acid group on the indole moiety is used to act as the molecular switch that activates the fluorescence signals at acidic and neutral conditions (ring opening) and fluorescence off under alkaline pH (ring closing). Furthermore, the fluorescent molecules substituted by Cl and Br can provide dipole-dipole force under acidic condition and thus self-assembly to form a hydrogel at low concentration. In order to improve the practicability of imidazole-indole derivatives, the L929 cells were examined and proved that it has good biocompatibility (cell viability above 90%). Overall, the introduction of halogen atoms can influence the fluorescence and self-assembly properties of imidazole-indole derivatives. We found that halogen substituents of imidazole-indole derivatives may have potential application in the field of optical components and bio-imaging in the future.
參考文獻
延伸閱讀
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