摘 要 本論文主要是探討，以benzoxazoles為主要中心core的液晶材料設計與物性。利用NMR來鑑定分子結構，元素分析來測量其純度。此外，並利用熱差掃瞄卡計(DSC)，powder X-ray，偏光顯微鏡，觀察其液晶相變化與分子排列情形。 在系列一之有機液晶分子結構中，我們固定較難合成的2-amino -5-dodecyloxyphenol側鏈碳數(n=12)，只改變另一邊側鏈基碳數，當n=1、4、6、8、10、12與14，具有SmC及N的液晶相。另外，我們也試著改變此有機液晶，將其單邊側鏈基由1根增加為2根及3根，但並沒有液晶相之形成。接著，我們也將此有機液晶分子，試著與金屬Pd配位。結果，我們雖然能成功地與金屬配位，但卻未能形成無機液晶。 將系列一的有機液晶分子結構稍做變化，而形成系列二的配位基。我們仍然固定2-amino-5-dodecyloxyphenol這一邊的側鏈碳數(n=12)。接著，我們將合成出來的配位基4-alkoxybenzoic acid 4-(6-dodecyloxybenzooxazol-2-yl)-3-hydroxyphenyl ester與金屬(M=Zn) 進行配位，得到具有液晶性質之含單金屬無機液晶。接著，我們將配位基與金屬Cu和Pd進行錯合時，並不具有任何液晶相。 Abstract Numerous known examples of hydrocarbon structures, used as core groups exhibiting columnar phases have been reported. However, examples of heterocyclic structures used as core groups are relatively less. The presence of nitrogen, sulfur or oxygen atoms on these heterocyclic rings, which likely introduce a transverse dipole moment often resulted in a change in dielectric anisotropy. The formation of liquid crystallinity in such heterocyclic compounds might be facilitated by weak p - p interaction between these aromatic or heterocyclic rings. In this work a new type of heterocyclic compounds, 4-alkoxybenzoic acid 4-(6-alkoxy benzoxazol-2-yl)phenyl esters, in which an unsaturated benzoxazole ring was utilized as the rigid core group, were prepared and their mesomorphic properties studied. All compounds were characterized by 1H-, 13C-NMR spectroscopy, powder X-ray diffraction and the mesomorphic properties of these compounds were studied by DSC analysis, optical polarized microscope and powder XRD diffraction. The results indicated that these rod-like compounds exhibited nematic (N) and smectic (SmC) phases. The range of mesophase temperatures was slightly dependent on the ratio of width-to-length (d/l, i.e., aspect ratio) of the molecular shape.
