蒽基三唑橋聯雙柱芳烴與雙芳杯螢光感測分子之合成及其分別對咪唑陽離子與對金屬離子辨識之研究

Abstract

此研究以修飾上疊氮基的蒽作為橋聯分子，以點擊反應 (click reaction) 與修飾有丙炔基的柱芳烴做連結，成功合成出蒽基三唑橋聯雙柱芳烴化合物40。並利用許多光譜方法與滴定實驗探討化合物40對G1-G8客體陽離子形成錯合物之能力與表現。 從化合物40的紫外可見光吸收光譜在加入G1-G8並無明顯的改變，在螢光放射光譜則顯示除G4之外的其餘客體均有螢光增強之現象。利用Hill plot計算化合物40對G1、G2、G5的Ka分別為2.80 × 105 M-1、5.87 × 104 M-1及6.25 × 105 M-1，形成錯合物的能力中以G5為最高。對不同碳鏈長度的咪唑分子G5-G7及二號位有甲基取代的G8作為客體，當碳鏈的長度減少會降低到主客體的錯合能力，G5-G7的Ka分別為6.25 × 105 M-1、8.78 × 104 M-1及6.42 × 104 M-1。G8則因立體障礙無法與化合物40進行錯合，失去螢光增強的能力。由NMR光譜顯示G8與化合物40並沒有生成錯合物。由NMR光譜滴定實驗及Job plot證明化合物40與G5以1:2形成錯合物。ROESY光譜說明化合物由碳鏈端穿入柱芳烴孔洞中。DOSY光譜顯示化合物40與G5確實形成錯合物40‧G5。 本實驗室先前的研究中針對蒽基三唑橋聯雙芳杯化合物44進行膠體測試，但並沒有進一步篩選測試。我們將橋聯雙芳杯44對15種不同的金屬離子進行篩選，發現其對Cu2+具有高選擇性的螢光淬熄現象。由先前實驗室的研究88以及螢光滴定、氫譜滴定及EPR實驗的結果推論，由於芳杯下緣羥基與金屬發生氧化還原反應導致螢光淬熄的現象產生。

We have synthesized anthryl triazole bridged pillar[5]arene dimer as compound 40 which containing anthracene as a fluorophore by click reaction. Compound 40 was analyzed by UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, ¬1H-NMR titration, ROESY and DOSY, which showed binding abilities toward different nitrogen-contained cations G1 to G5 and influence of varying substituted imidazolium G5 to G8. UV-Vis spectra of compound 40 didn’t change when G1-G8 were added. However, the fluorescence intensity of compound 40 was enhanced when G1, G2, G3 and G5 were added. The binding ability of compound 40 calculated by Hill plot showed that it binds stonger toward G5 than G1 and G2. Imidazolium with different length of carbon chains and 2-methyl substituted were also studied. Binding constant obtained by Hill plot became larger as the length of alkyl chain being longer. Furthermore, the more hindered imidazolium G8 showed no fluorescence enhancement ability of compound 40 compared with G6 which have equal length of alkyl chain. As results, we believed the methyl group on 2-position played an important role which increased the steric hindrance and prevented it from threading into the cavity of pillar[5]arene 40. As NMR spectra showed, no signal shift of G8 while mixing with 40 compared with G6 which means no complex was formed. DOSY also indicated that G8 cannot form a complex with compound 40. NMR titration and Job plot showed 40 and G5 formed 1:2 complex. 2D-ROESY spectra indicating alkyl chain side of G5 were penetrated into the cavity of pillar[5]arene. DOSY also demonstrated that a new complex was formed. According to the previous work of our laboratory, we have also synthesized biscalix[4]arene 44 using click reaction. The binding properties of host 44 toward 15 metal perchlorates were investigated by UV-Vis and fluorescence spectroscopy. The results showed that host 44 was highly selective toward Cu2+. Upon titration with Cu2+, the fluorescence of 44 was quenched (On-Off). Cu2+ was found to be reduced to Cu+ by host 44 according to the previous researchs in our laboratory.88