香豆素衍生物之合成及對於金屬離子感測之應用

Abstract

本文主要是研究針對金屬離子有偵測能力的螢光感測器，利用香豆素（coumarin）作為訊號轉換單元，改變不同的辨識單元，以研究不同的辨識單元對於金屬離子選擇性的變化。以聚乙醇（polyethylene glycol）為辨識單元合成化合物1、2，二氮雜18-冠醚-6（diaza-18-crown-6）為辨識單元合成化合物3、4，以及引入不同的酚類官能基，合成化合物5-8，最後是以香豆素-6作為訊號轉換單元，在胺基上3個苯環取代基的鄰位各引入1個羥基的化合物9。 由實驗結果可知，化合物1對於銅和汞離子均有明顯的螢光增強現象，尤以銅離子螢光增強11倍最為明顯。化合物3對於鉛和銅離子螢光增強較為明顯，在加入鉛離子時，在螢光光譜上有紅位移現象發生，但在加入銅離子時，則產生了藍位移現象。在化合物5-8中，則是對於多種金屬離子均有螢光增強表現，另外在有機溶液及水溶液的共溶劑系統中，也有不錯的螢光增強表現。最後在化合物9中，針對銅離子具有高度的選擇性，在螢光訊號上增強了12倍左右。

The main objective of this thesis is to design and synthesize fluorescent chemosensors for detection of metal ions. Coumarin fluorophores were chosen to serve as signal transducer. Various recognition units were coupled with the signal transducer units in order to investigate how these recognition units influence metal ion selectivity. Accordingly, fluorescent chemosensor 1-9 were prepared. Both fluorosensor 1 and 2 consist of polyethylene glycol as recognition unit. The preorganized recognition unit, diaza-18-crown-6, was employed in the case of fluorosensors 3 and 4. In order to improve water solubility and provide additional interaction elements for metal ions, a lariat phenolic group was introduced in the case of 5-8. Fluorosensor 9 features three phenolic groups around nitrogen center as recognition center in lieu of diethyl amino moiety of coumarin-6. Experimental results demonstrated that fluoresensor 1 displayed copious fluorescence enhancement in the presence of Cu2+、Hg2+, respectively. Fluoresensor 3 showed tight binding with Pb2+、Cu2+ with fluorescence enhancement, too. In the case of Pb2+, red-shift in fluorescence spectrum was observed, whereas blue shift was evidenced in the presence of Cu2+ ion. Fluorosensors 5-8 displayed high specificity for heavy metal ions, especially Pb2+. Either in organic solutions or oraganic/buffer cosolvent systems, large fluorescent enhancement was evidenced for Pb2+. Fluorosensor 9 displayed high selectivity for Cu2+ with 12-fold fluorescence enhancement in acetonitrile.