1,4 萘醌為基底的銅離子化學感測分子研究

Abstract

本論文合成了四種銅離子化學感測分子，分別為2-Methyl-3-[(pyridin-2- ylmethyl)-amino]-1,4-naphthoquinone (1)、2-Methyl-3-(2-pyridin-2-yl- ethylamino)-1,4-naphthoquinone (2)，1-[(Pyridin-2-ylmethyl)-amino]- anthraquinone (3)，1-(2-Pyridin-2 -yl-ethylamino)-anthraquinone (4)，評估作為陽離子偵測分子的可行性，並深入研究其感測機制及相關影響因素。 在1號與2號化學感測分子的研究中，Cu2+、Ni2+、Co2+、Fe2+、Fe3+、VO2+、Zn2+、Mn2+這幾種金屬離子加入化學感測分子後，Cu2+會使1號與2號化學感測分子產生顏色變化，顏色會由橘紅色變成深藍色，UV-vis吸收波長會由460 nm位移至640 nm。利用Job’s plot知道，在甲醇溶劑下，1號與2號化學感測分子與銅離子的鍵結比例均為1:1。有關pH影響研究發現，在pH 6~8下，銅離子加入1號與2號化學感測分子，吸收波長與顏色的變化最為明顯；在pH 1~5下，1號與2號化學感測分子的吸收波長產生藍位移，銅離子加入後吸收波長與顏色不會有太大的改變；在pH 9~10下，銅離子加入1號與2號化學感測分子，640 nm的吸收強度減弱(相對於中性條件下)。當溶劑改為乙腈時，銅離子加入1號及2號化學感測分子所產生的波長及顏色的改變會隨著時間而消逝，而 2號化學感測分子所產生的波長及顏色的變化相當微小，較不易觀測。 在3號與4號化學感測分子的研究中，Cu2+、Ni2+、Co2+、Fe2+、Fe3+、VO2+、Zn2+、Mn2+加入化學感測分子後，Cu2+是其中會使3號與4號化學感測分子產生顏色變化的金屬離子。當銅離子加入化學感測分子3號與4號時，顏色會由桃紅色變成藍色，UV-vis吸收波長會由490 nm位移至585 nm。利用Job’s plot知道，在甲醇溶劑下，3號化學感測分子與銅離子的鍵結比例不只一種，4號化學感測分子與銅離子的鍵結比例為1:1。當溶劑改為乙腈時，銅離子加入3號及4號化學感測分子所產生的深藍色會隨著時間而消逝，並恢復為深紅色。 由研究結果顯示，當Cu2+加入化學感測分子時，會與C=O、二級胺上的氮及pyridine上的氮產生鍵結，並使二級胺上的氫脫去。此時二級胺上所帶的負電以及Cu2+會影響苯環的共振系統，使π→π*的能階距改變，使得吸收波長及顏色發生改變。最後由EPR的測定可知，銅二價離子在與化學感測分子接合後，仍然是維持二價，並無改變形成一價。

In this thesis, four chemosensors, 2-Methyl-3-[(pyridin-2-ylmethyl)-amino] -1,4-naphthoquinone (1), 2-Methyl-3-(2-pyridin-2-yl-ethylamino)-1,4- naphthoquinone (2), 1-[(Pyridin-2-ylmethyl)-amino]-anthraquinone (3), and 1-(2-Pyridin-2-yl-ethylamino)-anthraquinone(4) were synthesized and evaluated for cation detection. In the binding study of 1 and 2 with transition metal ions, Cu2+ is the only ion caused maximum wavelength shifted from 460 nm (red) to 640 nm (blue). Job’s plot revealed that both sensors 1 and 2 reacted with Cu2+ in a 1:1 stoichiometry. Addition of Cu2+ caused great absorbance at pH > 6, indicating deprotonation of the secondary amine was required for Cu2+ binding. The maximum absorbance at 640 nm was observed between pH 7 and pH 7.4 which was the physiological pH in a cell. When pH > 8, the absorbance at 640 nm was lower than that in the pH range of 6-8 (likely due to the formation of CuLH-1OH). Furthermore, according to the results of solvent effect, the color change disappeared in a few minutes as solvent was changed to acetonitrile. In the binding study of 3 and 4 with transition metal ions, Cu2+ is the only ion caused maximum wavelength shifted from 490 nm (red) to 590 nm (blue). Job’s plot revealed that sensor 3 reacted with Cu2+ in more than one kind of stoichiometry. Job’s plot revealed that sensor 4 reacted with Cu2+ in a 1:1 stoichiometry. Furthermore, according to the results of solvent effect, the color change disappeared in a few minutes as solvent was changed to acetonitrile. Through the variation of UV-vis absorption and IR spectra, the sensing mechanism of 1, 2, 3, 4 with Cu2+ are investigated. As Cu2+ was added into the chemosensors, Cu2+ bound with C=O, secondary amine, pyridine and then let the hydrogen atom leave from secondary amine. Both the negative charge on secondary amine and Cu2+ influenced the resonance system of naphthoquinone. The energy gap was changed between π to π* and blue-shift was formed. From EPR spectrums, we know Cu(II) never changed to Cu(I) after it binding with chemosensors.