含蒽基異咢唑取代雙芳杯螢光感測器之合成及其分子辨識

Abstract

本論文利用1,3-偶極環化加成方法，成功的合成出雙芳杯化合物42-46。我們的合成策略是將炔基取代芳杯與具有雙腈氧取代的苯或蒽進行2+1和2+2反應，得到具異咢唑五環取代基雙芳杯化合物42、44和46。接著利用Mo(CO)6 將化合物42與44進行開環反應，形成具β-胺基-α,β-不飽和酮基取代基的雙芳杯化合物43與45。 由氫核磁共振光譜，我們發現化合物45為一組阻轉異構物，因異咢唑基團開環後形成β-胺基-α,-不飽和酮基，蒽基團C9-C10位置上的氫阻礙其自由旋轉，故產生阻轉異構物。 我們藉由紫外可見光譜與螢光光譜，研究螢光感測器44-46與客體分子結合性質。結果顯示，單橋聯雙芳杯化合物44對金屬離子進行篩選時，只對二價銅有選擇性，二價銅使化合物44產生螢光淬熄(on-off)的現象，由電子順磁共振光譜我們發現二價銅被還原成一價銅。 紫外可見光譜顯示，單橋聯雙芳杯開環化合物45對汞離子與銅離子有效應，乙腈中加入汞離子後，吸收光譜有些微紅位移。陰離子篩選方面，紫外可見光譜與螢光光譜都沒有明顯的改變。 由單晶結構圖中，我們可以看出雙橋聯雙芳杯化合物46具一扁平長方體孔洞，於是我們取化合物46，對芳香環客體分子和甲基紫精分子進行辨識研究。化合物46對芳香族類客體分子(A1-A6)沒有明顯的辨識效果；然而，化合物46當加入高當量甲基紫精客體分子，有螢光淬熄現象，由Stern-Volmer 方程式，可求得結合常數Ka = 132.9 M-1。

In this work, we have synthesized biscalix[4]arenes 42-46 using 1,3-dipolor cycloaddittion reactions. Our synthetic strategy for linking two calix[4]arenes involves double and quadruple cycloaddition between aryl dinitrile oxides and propargyl groups to form isoxazole biscalix[4]arenes, 42, 44 and 46. Mo(CO)6–mediated ring opening reaction of isoxazole linked biscalix[4]arenes 42 and 44, led to biscalix[4]arenes with enaminone groups, 43 and 45. Based on 1H□□NMR spectroscopy, we found that compound 45 composed of two atropisomers, because there is a hindered rotation around the C9-C11 bond of the□□-amino□□□□-unsaturated ketones. The binding properties of ligands 44, 45, and 46 toward guests were investigated by UV-Vis and fluorescence spectroscopy. The results showed that ligand 44 was highly selective to recognize Cu2+. Upon titration with Cu2+, the fluorescence of 44 was quenched (On-Off). Cu2+ was found to be reduced to Cu+ by ligand 44 as probed by EPR spectroscopy. Compound 45 showed specific responses to Hg2+ and Cu2+, when addition of Hg2+ to an CH3CN solution of 45, it’s UV-vis absorption was a slightly red shifted; whereas, it did not induced any significant change in UV-vis or fluorescence spectra when various anions were added. An X-ray crystal structure of 46 clearly shows that it’s contains a rectangular cone conformation. Biscailx[4]arene, 46, was used to test its inclusion the binding studies with aromatic guests, however, no inclusion between ligand 46 and aromatic guests (A1-A6) was found. The fluorescence intensity of 46 was decreased with the addition of high equivalent of methyl viologen, and the association constant Ka was determined to be 133□M-1 by Stern-Volmer plot.