含酯基、乙腈基團或四唑取代之偶氮芳杯化學感測器

Abstract

第一部分，我們合成出上緣具有推電子甲氧基之偶氮芳杯34 及 36。由紫外-可見光吸收光譜初步篩選實驗可得知，下緣修飾有單一 氧乙腈基團之偶氮芳杯34 及 36 在乙腈中皆對於Cr3+ 有很好的選 擇性；而引入醚酯基之34 則顯著的提升了對Ca2+ 的辨識能力。由 NOE、Job Plot 及氫核磁共振光譜滴定等實驗，可推測34 主要藉由 下緣兩個偶氮酚上的羥基，與氧乙腈基團協助對Ca2+ 離子進行一比 一之錯合，而醚酯基也輔助了錯合。並且， 34 與 Ca2+ 離子錯合後 會導致構形產生變化，由原本flattened cone 趨向於cone 構形。由 Benesi-Hildebrand plots 可求得34□Ca2+、34□Cr3+ 和 36□Cr3+ 錯合常數分別為3.7 □ 104、2.1 □ 104 及 8.1 □ 104。 第二部分，我們合成出偶氮酚對位具有拉電子之硝基的偶氮芳杯 38 以及 41。金屬篩選實驗可得知38 在較高極性質子性溶劑系統， 例如CH3CN/CH3OH (v/v = 19:1) 的溶劑系統中，仍然有能力對金屬 進行錯合。而41 則沒有此能力。由氫核磁共振光譜滴定實驗可推 測，偶氮芳杯38 除了下緣兩個偶氮酚上的羥基幫助之外，主要由氧 乙腈基團對Ca2+ 進行錯合，並由醚酯基輔助；對於Ba2+ 則藉由醚 酯基進行錯合，而氧乙腈基團也有所輔助。38□Ca2+、38□Ba2+、41□Ca2+和 41□Ba2+ 之錯合常數分別為7.3 □ 104、2.9 □ 104、1.7 □ 105 及 3.9 □103。 第三部分研究，則藉由偶極環化加成反應於芳杯下緣引入C5-單 取代四唑，合成出44。我們有效的提升偶氮芳杯在較高極性質子性， 例如含有甲醇或是水之溶劑系統中，對金屬之篩選能力，並增加芳杯 應用於離子篩選或生化及藥物領域上的潛力。

First of all, 4-(4-methoxyphenyl)azo-coupled calix[4]arenes 34 and 36 were synthesized. UV-vis screening of calix[4]arenes 34 (with ester and oxyacetonitrile) and 36 (with oxypropyl and oxyacetonitrile) with 15 metal ions showed that both of them gave rise to color changes toward Cr3+ ion, and 34 exhibited good binding ability to Ca2+. According to NOE, Job plot and NMR titration experiments, we proposed that 34 chelated Ca2+ with the helps of both oxyacetonitrile and ester groups, and it moved form flattened cone toward cone conformation upon complexation with metal ion. The Ka of 34□Ca2+, 34□Cr3+ and 36□Cr3+ calculated by Benesi-Hildebrand plots were 3.7 □ 104, 2.1 □ 104 and 8.1 □104 , respectively. In the second part, the syntheses of calix[4]arenes with 4-(4-nitrophenyl)azo calix[4]arenes 38 and 41 were carried out. UV-vis screening showed that calix[4]arene 38 exhibited large bathochromic shifts toward Ca2+ and Ba2+ in more polar protic solvent systems, such as CH3CN/CH3OH (v/v = 19:1). Moreover, 41 was deficient in this ability.The 1H NMR titration results suggested that both azophenols and ester/or oxyacetonitrile groups are required in the chromogenic sensing with metal ions. The Ka of 38□Ca2+, 38□Ba2+ , 41□Ca2+ and 41□Ba2+ were 7.3 □104, 2.9 □ 104, 1.7 □ 105 and 3.9 □ 103 , respectively. In the final part, the tetrazole-modified azocalix[4]arenes 44 were synthesized using 1,3-dipolar cycloaddition. We evaluated the metal ion screening abilities of azocalix[4]arenes in more polar protic solvent systems, such as CH3OH or H2O contained solvent systems. The utilities of calix[4]arenes in biological systems or pharmaceutical studies were improved upon tetrazole substitution.