含Ferrocene單取代液晶合成; Synthesis of the monosubstituted ferrocenomesogens

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題名:	含Ferrocene單取代液晶合成;Synthesis of the monosubstituted ferrocenomesogens
作者:	沈玟呈;Cheng-Wen Shen
貢獻者:	化學研究所
關鍵詞:	液晶;pyrazole;Ferrocene;metallomesogens;calamitic
日期:	2003-06-20
上傳時間:	2009-09-22 10:10:32 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本論文主要是探討含ferrocene unit之液晶材料的合成與物性。藉由改變柔軟長碳鏈之長度，及堅硬的核心(rigid core)數目，來觀察液晶相的形成與否。本實驗所合成之化合物藉由1H-NMR與13C-NMR光譜及元素分析來鑑定分子結構與純度。液晶現象的觀察是藉由偏光顯微鏡(POM)來觀察其光學紋理圖，再利用熱差式掃瞄卡計(DSC)來測定其相變化時之熱焓值變化，最後以變溫粉末X光繞射儀鑑定液晶相結構。在此論文中，我們合成出ferrocene unit接在桿狀型含pyrazole結構的有機液晶原末端，利用pyrazole間的氫鍵(NH----N)提供較強之分子間吸引力，抵抗ferrocene所造成的立體排斥，進而形成液晶相。實驗結果顯示，因ferrocene的立體排斥，使得分子不利於堆疊，形成液晶相範圍較窄的SmA相(約14~30 ℃)，且側鏈基之碳氫數長短對液晶相範圍沒太大影響。當改變pyrazole在液晶原的結構位置(與ferrocene的相對位置)，對分子間的吸引力有所改變，而出現不同的液晶相，且液晶相範圍亦有明顯差異。當增加液晶原的rigid core，即增加分子間的吸引力，可得到一極穩定且液晶相範圍較廣(平均約100 ℃)的N與SmC相 Studies focused on synthesis and mesomorphic properties of ferrocene-based metallomesogens have gained increasing importance in recent years. Ferrocene, because of its aromatic character, facilitates several substitution reactions whereby a range of low molecular mass calamitic (rod-like) systems can be prepared by monosubstitution, disubstitution of 1,1’-, 1,2-, 1, 3-position, or 1,1,3-trisubstitution on the ferrocene molecules. In reported ferrocenyl systems, most liquid-crystalline behaviour has been found to exhibit nematic (N), smectic A (SmA) or smectic C (SmC). The mesomorphic behavior may be due to the size of the ferrocene unit, in which two cyclopendienyl rings sterically interfere with the packing of the molecules, thereby preventing the build-up of long-range order that would result in the formation of a softer crystal phase. We describe herein the synthesis and mesomorphic of the mono substituted ferrocenecontaining liquid crystals. Their mesomorphic properties were investigated by use of polarized optical microscopy and differential scanning calorimetry(DSC). All the prepared compounds exhibit a smectic A mesophase.
顯示於類別:	[化學研究所] 博碩士論文

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