以芘為基底可偵測銅(II)及汞(II)離子之螢光化學感測分子

Abstract

本論文以芘(pyrene)為螢光基團，合成螢光感測分子1、MS1、MS2以及MS3。化合物1藉由產生明顯藍綠色螢光以辨識Cu2+離子，且於緩衝溶液中仍保有金屬離子選擇性，並能在pH 2~8.5範圍偵測Cu2+之存在。由Job plot得知1-Cu2+採2：1比例錯合，且根據Gaussian 09軟體運算之結果，推測化合物1欲與Cu2+錯合時，二個化合物1分子呈現交叉構形將Cu2+錯合於其中。化合物1對Cu2+結合常數為5.00 × 108 M-2、偵測極限則是2.73 μM；此外，其更可進一步應用於細胞實驗，於RAW 264.7 macrophage內表現偵測Cu2+之能力。 化合物MS1、MS2和MS3單一分子皆帶有二個pyrene結構，其於乙腈與水之混和溶液中，藉由原有藍綠色螢光淬熄為無螢光放射，以測定Hg2+離子，且於其它金屬離子同時存在之下仍具備選擇性。Job plot結果顯示，MS1、MS2與MS3對於Hg2+皆採1：1比例錯合。化合物MS1、MS2及MS3對Hg2+之結合常數分別為1.68 × 103、1.57 × 103與1.52 × 103 M-1；而偵測極限則各別屬於1.74、2.42以及3.83 μM。於細胞實驗中，化合物MS1也能在RAW 264.7 macrophage內對Hg2+具有偵測能力。

In this study, we developed pyrene-based fluorescent chemosensors 1, MS1, MS2 and MS3 for metal ion sensing. A new pyrene derivative (1) containing a benzothiazolenhydrazone moiety exhibited high selectivity for Cu2+ detection. Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu2+. However, the metal ions Ag+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+ and Zn2+ produced only minor changes in fluorescence values for the system. The apparent association constant (Ka) of Cu2+ binding in chemosensor 1 was found to be 5.00 × 108 M-2. The binding ratio of 1-Cu2+ complexes was determined as 2:1 according to Job plot. The maximum fluorescence enhancement caused by Cu2+ binding in chemosensor 1 was observed over the pH range 2 ~ 8.5. In addition, chemosensor 1 can be used as a fluorescent probe for detecting Cu2+ in living cells. Chemosensors MS1, MS2, and MS3 were synthesized from the click reaction of 1-(azidomethyl)pyrene with the corresponding poly- oxyethylene dialkyne to form a triazole ring between ether structure and pyrene. MS1, MS2, and MS3 containing two triazole units exhibited a fluorescence quenching in the presence of Hg2+ ions and a high selectivity for Hg2+ ions over competing metal ions in acetonitrile-water solutions; Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, Rb+ and Zn2+ produced only minor changes in the fluorescence of MS1, MS2, and MS3. The association constants (Ka) of MS1, MS2, and MS3 with Hg2+ were found to be 1.68 × 103, 1.57 × 103 and 1.52 × 103 M-1, respectively. The detection limits of MS1, MS2, and MS3 with Hg2+ were found to be 1.74, 2.42 and 3.83 μM, respectively. The binding ratio of MS1-Hg2+, MS2-Hg2+ and MS3-Hg2+ were determined as 1:1 according to Job plot. Moreover, fluorescence microscopy experiments showed that MS1 can be used as a fluorescent probe for detecting Hg2+ ions in living cells.