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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6288


    Title: 極性取代基對於彎曲型液晶分子的影響;The Effect of Polar Substituents on Bent-Core Liquid Crystals
    Authors: 林鈺翔;Yu-siang Lin
    Contributors: 化學研究所
    Keywords: 極性取代基;彎曲形液晶;氫建;紅外光譜;層狀排列;ent-Core Liquid Crystals;Polar Substituents;Smectic A
    Date: 2007-07-02
    Issue Date: 2009-09-22 10:17:01 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本系列以合成N,N’-bis[1-(4’-alkoxyphenyl)-3-oxopropenyl]-2- hydroxy-propylenediamines為架構的配位基液晶分子,所得化合物經由1H-NMR、13C-NMR、Mass與元素分析以鑑定其結構及純度;並由熱差式分析儀(DSC)、偏光顯微鏡(POM)及粉末 X 光繞射(XRD)鑑定其液晶相種類。探討及有無OH官能基及苯環上取代基對對液晶相的影響。由FT-IR 實驗確認配位基中存在著氫鍵,並一步研究 ligand中氫鍵對液晶相之影響,與 PL光譜的 excited state intramolecular proton transfer(ESIPT) 現象。我們在苯環上加入不同取代基則發現因立體障礙及極化因素影響了分子間的層狀堆疊。Pd錯合物在先前實驗室學長研究中則發現由分子間氫鍵自組裝產生盤狀液晶tetramer筒狀排列構形。 Dimmer系列為配位基1a之延伸。中間spacer在1’3’ diimine propane 2’位置無OH基時沒有液晶相產生;我們固定兩側碳鏈長(n = 12)試著增加中間橋接基長度(m = 2 ~ 12)後發現在中間碳鏈長度(m = 4 ~ 10)具有層狀排列液晶相的對稱二聚物;特別的是此系列具有一奇偶效應的性質。我們試著用短碳鏈單晶去了解其排列結構。 It is well known that the stability of the mesophase may be augmented by an increase of the polarity or polarization along the mesogenic core of the molecule. A substantial change of the micro- as well as macro-polarizability in a specific structure or molecule can be easily achieved by the introduction of polar substituent along the preferred molecular direction. The effect of polar substituents in a variety of mesogenic systems has been studied and investigated during the past years. Certain predictions were successfully made in terms of mesomorphic behavior. Previous studies also showed that compounds substituted with polar groups, such as -NO2, -CN, might lead to a higher clearing temperature. This effect was attributed to the conjugative interaction increased between the substituent and the ester moiety. On the other hand, the effect of polar substituents on the mesogenic 1,3,4-oxadiazoles was studied. The mesophase and optical properties of these oxadiazole materials were found to be strongly influenced by the presence of a terminal polar group. N,N’-Bis[1-(4’-alkoxyphenyl)-3oxopropenyl]-2-hydroxypropylenediamines and their Pd2+ complexes were previously prepared and found to exhibit columnar phase (Colh) in this group. However, the mesomorphic behavior of the ligands formed smectic phase due to the shape effect. In this work, a series of the similar structures with a variety of polar substituents, so-called bent-core (BC) mesogen was prepared and studied. All compounds were found mesogenic, and the mesophase was assigned tentatively as banana phases.
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