有機自組裝分子之合成及奈米微結構之鑑定與操控

Abstract

利用有機合成的方式，我們設計出一系列具有高度螢光量子效率的雙尿素分 子，在四氫呋喃溶液中自組裝形成奈米球狀分子。經由光物理性質量測，表現出 良好能量轉移效率，調配適當比例後，我們順利得到一具白色螢光奈米球。藉由 顯微技術觀察我們推測其成球的機制分為shrinking 和budding 兩種。另外，透過 KPFM 量測，奈米球具有電荷注入以及電荷儲存之特性，並由在奈米電極上擷取 到單顆奈米球之電致發光。近年來，陽極氧化鋁(anodized aluminum oxide, AAO) 模板塑型法蓬勃發展，我們運用其將這些具高度螢光量子效率的雙尿素分子從零 維的奈米球轉變成一維的螢光奈米管，並量測其偏光、光導及導電性。 同時，近年來在超分子化學領域不在侷限於單一分子單一微結構的研究，逐 漸轉移到賦予單一分子可調控的單元。我們以分子自組裝的基礎，沿用尿素(urea) 為其辨識基團，在核心結構中嵌入光致變色的分子設計(azobenzene)，結合 self-assembly 和photochromic 兩大概念，在一有序的微結構下，藉由一激發光 改變分子構型(trans to cis)，探討由分子層級之變化引導整體微結構轉換之關聯 性 同時，近年來在超分子化學領域不在侷限於單一分子單一微結構的研究，逐 漸轉移到賦予單一分子可調控的單元。我們以分子自組裝的基礎，沿用尿素(urea) 為其辨識基團，在核心結構中嵌入光致變色的分子設計(azobenzene)，結合 self-assembly 和photochromic 兩大概念，在一有序的微結構下，藉由一激發光 改變分子構型(trans to cis)，探討由分子層級之變化引導整體微結構轉換之關聯 性。

In this thesis, we synthesized amphiphilic urea-based molecules, which could self-assemble by hydrogen-bonding, with two core platform as π-conjugated systems and photochromic systems, then investigated their instinctive properties at the nano-structural level. The four highly emissive derivatives performed the spontaneous formation of spherical aggregates that can incorporate with different chromophores giving access to study of energy-transfer processes. Elucidation of the vesicular mechanism is explained briefly by electron microscopy as well as electrical injection/storage in the system by KPFM. Inter-spherical energy transfer and electro luminescence of single nano-sphere were also achieved in this work. The molecules above were also fabricated into 1-D nanotubes through the wetting of AAO porous templates. The polarization and waveguiding features of tubular structures and, further the electrical characteristics of single nanotube devices were reported. Along with the guideline in self-assembly, the photoresponsive azobenzene-based molecules containing biuret and bis-urea groups were prepared. It is demonstrated that molecules dominantly in trans-conformation self-assembled to form fibers and reversible fiber-sphere transition could be tuned by irradiation of assemblies while trans-cis photoisomerization took place into the molecular level.