含苯並咪唑–香豆素之金屬離子辨識之研究

本論文合成以苯並咪唑–香豆素作為骨架之化學感測器，其中在苯並咪唑中引入推、拉電子基而得到化合物B、T、NB以及含呸啶基團之化合物N。並以核磁共振光譜儀、質譜儀確認其分子結構。藉由紫外光可見光光譜儀與螢光光譜儀來探討光物理性質。　　溶劑效應中，觀察到化合物T具有激發態分子內質子轉移的性質，於質子溶劑中會抑制質子轉移之放射能力，使得放射波長的Stokes shift較小。　　金屬離子辨識行為於含水的異丙醇及四氫呋喃中進行，化合物B、T對於銅離子與汞離子具有辨識能力，在吸收光譜中導致310 nm強度下降，於400 nm強度上升，而在螢光光譜則使440 nm的放光被抑制，從藍色螢光而變成無螢光放射性質。NO2官能基的化合物NB則可透過吸收光譜變化來感測銅離子與鋅離子。經由Job’s plot實驗與滴定實驗來確認配位關係與結合常數，化合物B對於銅離子之配位比例為2：1，結合常數為3.41×109 M-2，而對於汞離子之配位比例為1：1，結合常數為2.26×104 M-1。

關鍵字

金屬離子感測器；苯並咪唑；香豆素；分子辨識

並列摘要

In this research, a series of chemical sensor of the coumarin framework containing of benzimidazole unit was synthesized. We introduced electron donating group and electron withdrawing group on benzimidazole moiety to gain compounds B, T, NB. Compound N containing perimidine moiety was synthesized, too. The structures of compounds were confirmed by NMR, mass spectrometry. All the photophysical properties were characterized by UV-vis spectroscopy and fluorescence spectrophotometer. In the study of solvent effect, compound T presented excited state intramolecular proton transfer (ESIPT) property in polar protic solvent, which inhibit emission from keto form and cause a smaller Stokes shift. Metal recognition behaviors were performing in isopropanol or tetrahydrofuran media containing of water. Compounds B and T showed the recognition ability toward Cu2+ and Hg2+ ions. When the metal ion was added, the absorption intensity about 310 nm was decreased and the intensity at 400 nm was increased gradually. Also the fluorescence emission around 440 nm was inhibited; it results fluorescence-OFF when metal ions were existed. Compound NB was capable to recognize Cu2+ and Zn2+ through UV-vis absorption spectra. Job’s plot and titration experiment confirm the metal-ligand relationship of binding and the association constant Ks. B-Cu2+ presented with 2:1 binding ratio, Ks was found to be 3.41×109 M-2, B-Hg2+ showed a 1:1 stoichiometry, Ks was found to be 2.26×104 M-1.

並列關鍵字

metal ion sensor ； benzimidazole ； coumarin ； molecular recognition

參考文獻

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