具有萘四羧酸二醯亞胺及萘二甲醯亞胺之有機共軛自組裝奈米材料

Abstract

近年來，科學家對分子的掌握日漸成熟，更進一步就是控制分子間的弱作用力，這一門領域便是自組裝材料的起源。本論文研究方向為探討一系列低分子量超分子自組裝奈米結構，主軸為探討其聚集方式誘導螢光特性及對酸鹼度敏感的感測器。研究主題分成兩個部分進行，各別著重在調控水凝膠流變性質和調控聚集誘導發光的能力。第一部份的萘四羧酸二醯亞胺連接的單肽能決定水凝膠的強度和成膠環境，比較了C8NDI-S、C8NDI-D、C8NDI-E和C8NDI-K，發現四者皆能形成穩定水凝膠，依據單肽的分子結構，S、E可在酸性條件下成膠，K可在鹼性條件下成膠，D則能在較接近中性的酸鹼值成膠。混合水凝膠S和K測試發現可在較接近中性的酸鹼值成膠。研究成果顯示出萘四羧酸二醯亞胺是個適合用於超分子水凝膠的系統。 第二部分比較了萘二甲醯亞胺連接上不同胜肽序列時聚集誘導發光的效果，依胜肽序列短到長分別是ppNI-DD、ppNI-FD、ppNI-FDD和ppNI-FDDD，除了DD之外其他三者皆能在酸性條件下形成穩定水凝膠，胜肽部分則選用天冬氨酸和苯丙胺酸的組合，藉由苯丙胺酸的苯環提供成膠作用力，天冬氨酸的親疏水性改變就能調控聚集誘導發光的表現，使得在1%二甲基亞碸的水溶液中也能有最佳的聚集誘導發光效果。本研究是第一個利用萘二甲醯亞胺與胜肽產生聚集誘導發光的系統。

In this study, the  conjugated systems are modified by attaching peptide sequences to improve functionality for applications. This thesis has two different parts. In the first part, we study the rheological properties of peptide hydrogels. Incorporation of a Naphthalene Diimide (NDI) and a single amino acid in the imide position, we found that different amino acid derivatives can determine the strength and gelation properties of this self-assembled hydrogels. The four compounds are presented in the study (C8NDI-S, C8NDI-D, C8NDI-E and C8NDI-K) which forms stable hydrogel in a wide range of pH conditions. The use of S or E can form hydrogels under acidic condition. The presence of K can facilitate the formation of the hydrogel in basic condition. The usage of D can gel water in neutral condition. This work illustrates the importance of the structure-property relationship on the development of new nanoscience and self-assembly nanomaterials. It also suggests that Naphthalene Diimide is an efficient hydrophobic component in the formation of hydrogels. In the second part, we study the properties of aggregation-induced emission (AIE) of the chromophores. Piperidine was used as electron-donating group to modify the 1, 8-naphthalimide (ppNI). Importantly, the ppNI series exhibit AIE properties. We further extend this study to multiple amino acids where the combination of ppNI and phenylalanine (Phe) or aspartic acid (Asp) was conducted. The materials have significant differences in their fluorescence intensity, which have a higher emission peak at acidic conditions. The number of aspartic acid can alter the hydrophilicity of hydrogels and the properties of AIE. Through this study, we found a simple strategy to construct the one-dimensional (1-D) nano- and micro-structures in relatively large scale.