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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6053

    Title: 含雙benzoxazole環之對稱性液晶分子;The liquid crystallinity of symmetric dimers based on the benzoxazole mesogenic unit
    Authors: 李馥戎;Fu-Jung Li
    Contributors: 化學研究所
    Keywords: 桿狀;對稱性液晶分子;benzoxazole;mesomesge;liquid crystal dimers
    Date: 2004-06-28
    Issue Date: 2009-09-22 10:12:30 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 中文摘要 系列一:設計並合成出一系列具有雙benzoxazole mesogenic units的對稱性液晶分子,以碳數不同的碳鏈(spacer)做為橋接,探討不同的碳鏈長度對液晶分子的影響。所有化合物皆經由1H- 與 13C-NMR光譜、元素分析及質譜分析加以鑑定其結構與純度;而液晶現象的觀察與分析則藉助熱分析儀(DSC)、偏光顯微鏡 (POM)以及粉末X光繞射(PXRD) 來判斷。實驗結果顯示此系列含benzoxazole mesogenic unit的對稱性液晶分子呈現出桿狀液晶相。當中間橋接基為5、7、9與11同時側鏈基碳數n = 8、10、12或14時化合物具有液晶相。此外,還合成出一具不對稱結構,分子化合物當中間橋接基的碳數為5、7或9時化合物具有一個 SmC相,但與金屬Pd2+配位後錯化合物則不具液晶相。若將中間橋接基取代為1, 3位置的苯環時,分子本身因太多的雜環使得吸引力過大且單鍵可旋轉,所以無法產生所預期之香蕉型液晶相。 系列二:設計並合成出一系列具有salicylalimine的結構與Pd(OAc)2配位而形成之無機桿狀液晶。所有錯合物皆經由1H- 與 13C-NMR光譜、元素分析及質譜分析加以鑑定其結構與純度,並且進一步利用單晶X光繞射解出其中兩個分子的正確結構。所有之ligands具有nematic phase或smectic C phase之桿狀液晶相。與Pd金屬配位之錯合物也同樣具有nematic phase或smectic C phase;而形成Pd錯合物之後溫度範圍液晶相明顯變寬廣許多,藉由熱分析儀(DSC)以偏光顯微鏡(POM)及粉末X光繞射(PXRD)來判斷液晶相的形成。 Abstract A novel system of symmetric and non-symmetric dimers containing benzoxazole units through ester linkages to the terminal chains have been synthesized and investigated for their thermal behaviour. The mesomorphic behaviour of these compounds was characterised by polarised optical microscopy, differential scanning calorimetry and powder X-ray diffraction. All symmetric dimers linked by a methylene spacer -(CH2)n containing from n = 5 to n = 11 exhibited nematic phase (N) or smectic A phase (SmA). The temperature range of smectic A phase increased with terminal carbon chain length, and decreased with the carbon length of the spacer. The structure of the smectic A phase was confirmed by powder X-ray diffraction, and the data also indicated that the symmetric dimers were in fact arranged by monolayers and not intercalated. In these dimers, the spacer length has a remarkable influence on the thermal behaviour. A series of palladium(II) complexes derived from 4-dodecyloxy phenyl-2-carboxylic acid-4-[(3,4-didodecyloxyphenylimino)methyl]-3- hydroxyphenylester was prepared and characterized. Liquid crystalline properties of these palladium (II) complexes were studied and investigated by differential scanning calorimeter (DSC) and polarized optical microscopy (POM). The structures of the mesophases for palladium (II) complexes were also characterized and confirmed as nematic phase or smectic C phase depending on the terminal chains. The formation of mesophases was sensitive to the numbers of the alkoxy side chains and the carbon length of the side chains. The crystal and molecular structures of the complex were determined by means of x-ray analysis. The complex was crystallizes in the triclinic space group P1.
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