具有光與酸鹼響應性的單與雙三唑偶氮苯胺修飾之混摻型柱芳烴衍生物之合成與其自組裝超分子聚合物研究

Abstract

本文成功利用1,3-偶極環化加成之方式，分別經由五個步驟合成出單與雙三唑偶氮苯胺修飾之混摻型柱芳烴化合物40和41，總產率分別皆為4%，並研究它們自組裝形成具有光與酸鹼響應性超分子聚合物的性質。單取代混摻型柱芳烴40上修飾的胺基可利用酸與鹼進行質子化的調控。在中性狀態下，當濃度由2.5 mM逐漸升高至75 mM時，利用DOSY光譜法所測得的擴散係數從8.32 × 10-10 降低至6.02 × 10-10 m2/s；經由酸化將胺基轉變為銨離子，濃度一樣由2.5 mM逐漸升高至75 mM時，其擴散係數則從6.18 × 10-10 降低至3.20 × 10-10 m2/s，代表酸化單體所形成的超分子聚合物之分子量比中性單體所形成的要來的大，也表示單取代混摻型柱芳烴40可利用酸來提升自組裝超分子聚合物的聚合性，並利用鹼使銨離子轉變回中性胺基來降低其聚合性。柱芳烴41在酸化後即產生沉澱，無法進行後續的超分子聚合物測試，但柱芳烴41能與甲氧基柱芳烴DMP5自組裝形成雙組成超分子聚合物。接著，我們利用變濃度1H NMR、NOESY與ROESY光譜來推測單體間自組裝的方式，並藉由掃描式電子顯微鏡來探討此類超分子聚合物的形貌。 偶氮苯可藉由照射紫外光與可見光產生順反異構化，我們利用紫外-可見光吸收光譜分別證實單取代混摻型柱芳烴40與雙取代混摻型柱芳烴41的順反構形可逆性。然而，由DOSY光譜所測得照光前後的擴散係數僅有小數第三位的差異，顯示單體自組裝形成的超分子聚合物之聚合度並不會受到偶氮苯順反構形變化的影響。

Mono- and di-triazolyphenylazoaniline modified copillar[5]arenes 40 and 41 were synthesized using 1,3-dipolar cycloaddition reaction in five steps and with 4% overall yield, respectively. We then studied the photo- and pH-responsive properties of the supramolecular polymers that were obtained from the self-assembly of compounds 40 and 41. On the one hand, the aniline in compound 40 can be transformed into ammonium ion by adding acid, hence, the supramolecular polymerization degree of 40 can be enhanced. On the other hand, the ammonium ion state could be switched back to the neutral amine state by adding base, which reduces the degree of supramolecular polymerization. In contrast to acidified monomer 41 that precipitated in solution, neutral monomer 41 could form supramolecular polymer with the addition of dimethoxypillar[5]arene DMP5. These results were confirmed and supported by variable-concentration 1H-NMR, DOSY, NOESY, and SEM experiments. Furthermore, the cis-trans isomerization of the azo groups in compounds 40 and 41 was found to be photo-reversible as observed by UV-Vis absorption spectra; however, their polymerization degree was not affected by the cis-trans isomerization. As the concentration of monomer 40 increased from 2.5 to 75 mM, its diffusion coefficient decreased from 8.32 × 10-10 to 6.02 × 10-10 m2/s. Interestingly, after acidification of monomer 40, its diffusion coefficient decreased from 6.18 × 10-10 to 3.20 × 10-10 m2/s, signifying that the supramolecular polymerization of 40 could be enhanced by adding acid.