- 學位論文
合成冠狀醚—奈米材料衍生物應用於金屬離子感測之研究
Synthesis of crown ether-nanomaterial derivatives for application in metal ion sensing
摘要
化學感測器（chemosensor）是對於特定物質有辨識能力以改變其感測器的光電性質並處理及轉換成訊號。金屬離子感測在環境汙染物的監測當今科技工業迅速發展的年代是對於生態永續發展非常重要的課題。尤其當越來越多的慢性疾病被發現與人體攝取過多的重金屬離子有相關性，化學研究學者已經發展出不同的方法去做金屬離子感測。例如，利用修飾電極表面以增加特定金屬離子的親和力來觀察電流或電位的變化；合成特殊結構的化合物，當化合物與特定金屬離子交互作用時可以使得系統產生光子訊號，已達到金屬感測的目的。金屬離子感測器的發展已經超過百年，新興物質的發展已經大幅提升金屬離子感測的靈敏度以及專一性。本研究主要目的在設計對金屬離子具有專一性的螢光感測分子材料。螢光感測分子材料主要使用冠狀醚（crown ether）作為金屬離子的辨識單元，並化學鏈結到不同的訊號輸出單元，包含羅丹明（rhodamine）、硒化鎘量子點（CdSe Quantum dots）、矽量子點（silicon quantum dots）、中孔洞二氧化矽奈米粒子（mesoporous silica nanoparticle），討論不同大小及不同雜環原子種類的冠醚分子對金屬離子選擇性。 實驗結果得到：第一、羅丹明-15-冠-5與硒化鎘量子點-15-冠-5共軛物（RBCE-QDCE）對於鉀離子能形成三明治錯合物，具有高效的螢光共振能量轉移（Förster resonance energy transfer, 44％）。第二、氮雜冠狀醚（aza-crown ether）修飾於矽量子點（SiQDs）表面，我們發現氮雜-15冠-5-矽量子點能夠專一選擇鎂離子、氮雜-18-冠-6-矽量子點專一選擇二價錳離子、二氮雜-18-冠-6-矽量子點專一選擇鈣離子。其原理是利用金屬離子對於氮雜冠狀醚有專一選擇性，而冠狀醚上的氮雜原子具有光誘導電子轉移（photoinduced electron transfer）性質能夠淬熄矽量子點的光致發光。第三、螺環內醯胺-羅丹明B鏈結不同大小環的冠狀醚（sRBCEs）分別對四價錫離子有螢光感測能力。第四、更進一步地，將螺環內醯胺-羅丹明B修飾上中孔洞分子篩（SBA-15-sRB）發現對於鋁離子有專一選擇性。螺環內醯胺-羅丹明B（Spiro-lactam Rhodamine B）能夠與金屬離子配位形成錯合物，並將原始羅丹明B的螢光恢復以達到螢光感測的效果，稱之螯合增強螢光（chelation-enhanced fluorescence）。
並列摘要
A chemosensor is a kind of molecular structure that is used for sensing of a specific analyte to produce a detectable change or a signal. Metal ion sensing in environmental pollutants monitoring is an important issue of sustainable development. While rapid industrial development, many diseases were found to be associated with excessive diet of metal ions. Chemists had developed vary of methods for metal ion sensing. For example, the modified electrode can increase the affinity of specific metal ions, and it can be observed changes in current or potential. Synthesized specific structure molecule can interact with a specific metal ion, and the molecule can transduce a photon signal, which has achieved the purpose of metal sensing. Metal ion sensors had been developed for many decades, and new materials was found and greatly improved the sensitivity and specificity of metal ion sensing. The main purpose of this study was to design a fluorescent sensing molecular material, which is specific to metal ions. Fluorescent sensing molecular materials mainly composed of crown ether as the identification unit of metal ions, and chemically bonded to different signal output units, including rhodamine B, CdSe Quantum dots, silicon quantum dots and mesoporous silica nanoparticles. The selectivity of the crown ether molecules using different sizes and different heterocyclic atom was discussed. The experimental results show that: First, 15-crown-5-ether attached rhodamine B and 15-crown-5-ether capped CdSe/ZnS quantum dots conjugate (RBCE-QDCE) formed a sandwich complex with potassium ions by fluorescence resonance energy transfer (44%). Second, the aza-crown ether was modified on the surface of silicon quantum dots (SiQDs). It was found that the sensing of multiple metal ions including magnesium ion, manganese(II) ion and calcium ion by using diverse aza-crown ether-functionalized SiQDs based on the suppression of PET process and further demonstrate their sensing efficiency. Third, the chemosensor (sRBCEs) composed of rhodamine B with 15-crown-5/18-crown-6 can detect the tin(IV) ions and showed florescence recovery in the presence of these ions, respectively. Fourth, furthermore, the spirocyclic rhodamine B modified with SBA-15 (SBA-15-sRB) had showed specific selectivity for aluminium ions. Spiro-lactam rhodamine B can form a complex with metal ions, and then rhodamine B fluorescence recovered to achieve metal ion sensing, called chelation-enhanced fluorescence.