半氟鏈對五苯荑−蒽π系統衍生物之光機械性質調控之研究

Abstract

光響應的有機晶體已經成為一類新的傳感器和執行器材料。本實驗室先前發展了一系列五苯荑-蒽衍生物P(Cn)，通過改變五苯荑中心環的烷基鏈長度，具有不同的同質多形體，因為晶體內部不同的排列模式，使晶體的剛硬性有所不同，蒽環在發生二聚化反應時表現出特殊的光機械力致螢光變色(Photomechanofluorochromism, PMFC)現象。近期，實驗室將氟原子引入烷基中，合成出具有半氟烷基鏈的F-C4C4化合物，晶體在光刺激下，由於二聚體不均勻的產生，毫米級晶體發生伸長及彎曲的光機械效應，同時具有彈性彎曲的現象，此性質在過去文獻中相當少見。 本研究乃針對F-C4C4化合物作進一步分析和討論，包含利用共軛焦顯微鏡了解晶體的PMFC性質，利用奈米壓痕來測量晶體對外部應力的適應性，也記錄了晶體的伸長前後的三維變化量及利用粉末繞射來探討晶體在光機械效應過程中的變化，排除晶體晶格缺陷造成晶體伸長的可能性。 另外，透過設計不同碳氟鏈取代之分子，分別為F-C4C2、F-C4C8、F-C8C4、F-C3C8，對其進行晶體結構、光物理參數、二聚體程度與F-C4C4比較，深入探討氟鏈對光機械效應及彈性彎曲的變化機制。

Photo-responsive organic crystals have emerged as a new class of sensor and actuator materials in recent years. Our laboratory has previously developed a series of pentiptycene-anthracene derivatives P(Cn) by changing the length of the alkyl chain. P(Cn) exhibits a special polymorph-dependent photomechanofluorochromism (PMFC) during photodimerization. Recently, fluorine atoms were introduced into the alkyl chain to form compound F-C4C4 with a semi-fluoroalkyl chain, and its rod-shaped crystals are elastic. In addition, when the crystals are irradiated with light, the millimeter-scale crystals undergo elongation and photomechanical bending due to the generation of dimers. This property is quite rare in the literature. In this thesis, the photomechanical properties of F-C4C4 are further explored, including the use of confocal microscopy to understand the PMFC propertie, the use of nanoindentation to measure the hardness and elastic modulus, the investigation of the crystal size effect on elongation, and powder X-ray diffraction anaylsis on the irradiated crystals.We also designed and synthesized compounds F-C4C2, F-C4C8, F-C8C4 and F-C3C8 differing in the fluoroalkyl chain for studies and comparison with F-C4C4 in their photomechanical and mechanical properties.