| 摘要: | 摘 要 本論文研究主要分成兩個系列共四個部分。所有化合物經由1H-NMR、13C-NMR、Mass與元素分析以鑑定其結構及純度，液晶相性質則是利用偏光顯微鏡 (POM)來觀測及熱微差掃描分析儀(DSC)測量。系列一：第一部份是合成出具有benzoxazole環的液晶分子，探討取代基之種類對於液晶相生成之影響。實驗發現當取代基導入分子時，會使原不具液晶相的分子具有液晶相，且具拉電子基的液晶相範圍較推電子基為寬；具拉電子基的分子具有SmA或SmC相，推電子機則多為N相；第二部分是固定取代基為CN或OCH3，改變側鏈長度及固定側鏈長度，改變不同取代環對分子的影響。結果發現澄清點隨側鏈增長而降低；當取代環改變時，也有機會使不具液晶相的分子產生液晶相，但液晶相範圍不如第一部份的結果來的長。 系列二：第一部份是合成出具有benzoxazole環的配位基，來探討與金屬銅配位後化合物液晶相的改變。結果發現配位基與銅錯合物皆具有液晶相，銅錯合物的澄清點較配位基高；第二部分則是選擇不同金屬(Ni, Pd, Co, Zn)，探討液晶相生成的影響，結果發現配位金屬為Ni、Pd時具有液晶相，Co、Zn則無液晶相。 Abstract In this thesis, we report the synthesis, characterization and mesomorphic properties of two novel series of new mesogenic derivatives based on [4-(6-alkoxybenzoxazol-2-yl)phenyl]-4-X-benzy lidenes (as shown below, X = CN, F, Cl, NO2, OCH3 and etc.) and metal complexes of 5-alkoxy-2-{[4-(6-alkoxybenzoxazol-2-yl)phenylimino] methyl}phenols. These compounds were all characterized by 1H-NMR and 13C-NMR spectroscopy, and their mesomorphic properties were studied by differential scanning calorimeter (DSC) and polarized optical microscopy (POM). The results indicated that all compounds exhibited nematic (N) and/or smectic A phases (SmA) and/or smectic C phases (SmC), as expected by rod-like molecules. In addition, the mesomorphic properties observed by these compounds were found to be strongly dependent on the terminal group attached. The effect of mesomorphic properties, which was determined by the electronic and/or steric configuration of the terminal groups, will be also discussed. For example, smectic A phase was observed for the derivative with CN attached as terminal group, however, nematic phase was in fact observed for the derivative with OCH3 group. The effect of the carbon chain length of side chains on the mesomorphic properties will be also investigated. Copper(II), palladium(II), and nickel(II) complexes exhibited mesomorphic properties, however, cobalt(II) and zinc(II) complexes were not mesogenic. |
