(I)三蝶烯衍生化杯[6]芳烴︰合成策略改進之探討 (II)含蒽基三唑取代三蝶烯之合成與其對金屬離子之螢光感測研究

Abstract

第一部份中，我們嘗試合成三蝶烯衍生化杯[6]芳烴30及31，期望進一步以點擊化學反應接上螢光發射基團，用於感測特定有機小分子。然而步驟冗長且整體產率不甚理想，未能進行廣泛的應用。為使化合物30及31之合成更加簡便，我們針對其反應路徑進行研究及更改。利用改進的Marschalk 反應接上羥甲基側鏈得到化合物45，接著將化合物45之1, 8位置以甲氧基保護可得化合物46。進一步將化合物46還原成蒽衍生物50後，以苄基保護羥甲基得到化合物51，再進行狄爾斯－阿爾德環化加成反應形成三蝶烯片段52，最後以Pd/C催化劑與還原劑1,4-環己二烯去除苄基保護，成功得到三蝶烯組件32。相較於文獻的3.3% 總產率，我們將產率成功提升到8.8%，並縮短反應步驟，能更簡便的合成大量化合物32。

在第二部份，我們成功以三唑雜環取代基作為架橋及離子辨識基團，連接三蝶烯與螢光發射基團蒽基，組合成「三蝶烯－架橋－螢光基團」形態的螢光感測分子54。經由紫外－可見光光譜與螢光光譜初步篩選得知，化合物54於無水THF中對16種金屬離子中的Ag+及Hg2+有明顯的螢光增強現象，但對於Cu2+ 卻有螢光淬熄的效果。利用1H-NMR滴定光譜，可以推論化合物54對此三種金屬離子有二種不同的錯合方式︰(1) 加入Ag+ 及Hg2+後，三唑雜環與金屬離子錯合導致構形上的改變，進而使螢光增強；(2) 在Cu2+的錯合過程中，三唑雜環與Cu2+有明顯的錯合，且伴隨三蝶烯的氫原子訊號明顯改變，Cu2+藉由氧原子的協助，與三蝶烯的內部自由空間螯合，並因重原子效應，使得螢光減弱。

In the first part, we planned to synthesize triptycene-derived calix[6]arene 30 and 31, followed bt attachimg fluorophore through click chemistry, hoping that they can be used for the sensing of small organic molecules. However, we found that the synthesis is lengthy and low yield, making it difficult to use triptycene-derived calix[6]arene as a common host. In order to make the synthesis of 30 and 31 shorten steps and high yiels, we analyzed the synthetic schemes and made several improvements. First, we change the reaction condition of Marschalk reaction to attach hydroxymethyl on 2,7 positions and using methoxy group to protect the 1,8-dihydroxyl groups. After reduced anthraquinone to anthracene, we then used benzyl bromide to protect the hydroxymethyl group followed by Diels-Alder reaction to obtain the triptycene motif. Last, we chose 1,4-cyclohexadiene as reducing reagent and Pd/C as catalyst to deprotect benzyl group and successfully obtained the triptycene 32. Compare to the literature, our synthetic scheme is shorter and the overall yield increased form 3.3% to 8.8%, making the big quantity synthesis of 32 feasible.

In the second part, triazolyl methyl anthryl substituted triptycene 54 was successfully synthesized, where the anthryl methyl is the fluorophore while the triazolyl group is not only the bridge unit but also the ion recongnition ligand. Compound 54 was found to show a high selectivity toward Ag+, Hg2+ and Cu2+ in anhydrous THF. The chelation of the Ag+ and Hg2+ shows fluorescence enhancement, but the coordination of Cu2+ shows fluorescence quenching. 1H-NMR titration spectra imply that these three metal ions use two different ways to bind with compound 54: (1) After added Ag+ or Hg2+ ions, triazolyl group would coordinate with metal ions and cause conformation chaged, make fulorescence enhanced. (2) The fluorescence was quenched due to the dynamic quenching of Cu2+ by the triptycene 54 and its heavy atom effect.