以旋環雙芴為主體新型分子感測器之設計與合成

Abstract

本篇研究內容主要在設計以旋環雙芴（spirobifluorene）為主體的新型分子感測器。利用旋環雙芴中心sp3混成的碳，區隔成二個不互相共軛的系統，分別在這二個系統上引入予體（Donor）和受體（Acceptor） ，利用與分析物之作用而調控光子激發電子轉移（Photoinduced electron transfer）的機制，作為分子感測器偵測的原理。而本篇設計的分子感測器所偵測的分子分別為一氧化氮（Nitric oxide）及金屬陽離子，化合物 DAO、DAS 為一氧化氮感測器，CN-AC、OXD-AC 為陽離子感測器。 （一）DAO、DAS：一氧化氮（Nitric oxide）是人體中不可缺少的重要物質，一氧化氮除了可以讓血管擴張、預防動脈粥樣硬化症、防止血小板凝結和白血球黏著於血管壁上，還是身體對抗心臟病發作和中風……等疾病最堅強的自我防禦。在生物體內，一氧化氮很容易和自由基以及含有金屬的蛋白質反應，這些反應會造成生理和病理上的變化。所以，藉由偵測一氧化氮，就能進而研究生物體內許多的分子行為。我們設計了以旋環雙芴（spirobifiuorene）為主體的分子感測器來偵測一氧化氮，並對其螢光的變化作探討。 （二）CN-AC、OXD-AC：金屬離子（如：鉀、鈉、鈣、鎂…等。），在我們所居住的環境或是人體裡都是很重要的物質。所以，偵測金屬離子也是分子感測器最常應用的範疇。在這個部分，藉由引入azacrown來和金屬離子結合，發光團的部分則使用量子產率高的旋環雙芴。利用光子激發電子轉移（photoinduced electron transfer）的原理，造成螢光的增減，來觀察是否偵測到金屬離子。經由實驗發現CN-AC、OXD-AC對於二價銅離子具有很好選擇性。

We have designed novel chemosensors based on spirobifluorene as a core for sensing nitric oxide and cations. We have introduced a π- conjugated donor onto one branch of spirobifluorene, where as a π- conjugated acceptor was attached to another branch. The resulting spiro - configured bipolar systems exhibit strong photoinduced electron transfer reaction upon excitation with light, resulting in weak fluorescence. Upon reacting with the analytes, i.e. nitric oxide or cations, the efficient PET pathway was strongly blocked, leading to light on the fluorescence. Nitric oxide can be detected by DAO and DAS. When DAO reacted with nitric oxide, the mechanism of PET was suppressed, rendering the intensity of fluorescence strongly enhanced. On the other hand, DAS can also sense nitric oxide. Upon reacting with nitric oxide the emission wavelength of DAS had changed dramatically from 393 nm to 494 nm. The cations can be sensed by CN-AC、OXD-AC, we introduced aza-18-crown-6 as the cations recognition site. From our titration experiments, we found that CN-AC and OXD-AC have excellent selectivity to Cu（I）. The fluorescent intensity have enhanced 20-folds for CN-AC and 150-folds for OXD- AC upon treating CuClO4. The color of solution have also changed from yellowish to light red.