Calixarenes是一種由甲醛 (formaldehyde) 和酚 (phenol) 所聚合成的環狀聚合物，由於這類分子具有分子內中空，因此可以嵌合小型的有機分子或金屬離子，而形成 "主-客化合物" (host-guest)，此特性可推廣應用在微量金屬檢驗，離子萃取分離及酵素模擬的研究。而本論文研究之主要目的在於研究如何將 calix[4]arene 鍵結於矽膠上，以製備出 calix[4]arene grafted silica gel，再進一步的研究其對金屬離子的選擇性，並期望能發展出能進行金屬分離的矽膠產物。
三級丁基酚 (p-tert-butyphenol) 和甲醛 (formaldehyde) 在鹼性的催化下，可聚合成黃綠色的聚合物，我們稱此化合物為前驅物。此前驅物可以在二苯醚 (diphenyl ether) 的迴流下，被轉換成 p-tert-butylcalix[4]arene；此環狀聚合物的對位三級丁基可利用三氧化鋁 (AlCl3) 進行反向的 Friedel-Crafts 反應，進行減除而得到對位無取代之 calix[4]arene。
Calix[4]arene 能利用標準的四步驟製程，來鍵結到矽膠上。利用3-aminopropyl triethoxy silane 可將3-aminopropyl 的官能基團鍵結到矽膠上，而得到化合物 aminopropyl silica gel (APSG)；APSG可和p-nitrobenzoyl chloride作用而引進硝基苯官能團；接著硝基苯官能團可用sodium dithionite來進行還原而生成苯胺官能團；最後再利用偶氮偶合反應和calix[4]arene作用，便得到紅色的calix[4]arene grafted silica gel化合物。此一 calix[4]arene grafted silica gel在經過TGA的儀器分析後可推算出在每一單位重量下的 silica gel 可鍵結約18.5%重量百分比的 calix[4]arene 有機分子團。
此一數據可以讓我們在使用 calix[4]arene grafted silica gel 去檢測金屬離子時，在與矽膠對照組做比較之後，可判定出所能吸附金屬離子量的多寡。化合物之合成製備的條件、 TGA 分析的結果以及原子光譜分析的鑑定結果，在論文中有詳細之敘述及說明。
Calixarenes, which are cyclic oligomers of p-substituted phenols and formaldehyde, are able to include small organic molecules or metal ions within molecular cavities to from the “host-guest complexes”. This phenomenon has been proposed in the research area of micro-analysis detection devices, ion separation, and enzyme-mimic studies. The main purpose of this thesis is to develop a standard procedure for grafting the calix[4]arene onto silica gel. The grafted product was then subjected to serve as a stationary phase for the ion separation.
In the presence of a base, p-tert-butylphenol and formaldehyde was polymerized to form an yellowish precursor. Refluxing of this precursor in diphenyl ether for two hours yielded the p-tert-butylcalix[4]arene. The p-tert-butyl groups were then removed by AlCl3 catalyzed reverseFriedel-Crafts reaction to give parent calix[4]arene.
The calix[4]arene grafted silica gel was prepared in a four-step procedure. An 3-aminopropyl groups was introduced
by reacting triethoxy silane with silica gel, and the resulting aminopropyl silica gel (APSG) was further treated with p-nitrobenzoyl chloride to supply a p-nitrobenzoate moiety. The nitro group was then reduced by sodium dithionite, and the diazotization of the resulting aniline followed with diazo-coupling reaction with calix[4]arene gave the red calix[4]arene grafted silica gel.
The thermal gravimetric analysis (TGA) was applied to the products to determine the composition of the organic portion on grafted silica gel. The amount of the organic portion was in the range of 18.5% for the calix[4]arene grafted silica gel, which is equivalent to 3.02 mmole of calix[4]arene per gram of calix[4]arene grafted silica gel . The preliminary ionic extraction resulted for Cu+2 , Fe+2 , Pb+2 , and Cr+3 will also be discussed.
