| 摘要: | 本篇論文包含兩種具有benzoxazole結構之有機及無機液晶。 系列一為具有萘環及benzoxazole結構之無機液晶，此系列以化合物2 ( 6-alkoxynaphthalene-2-carboxylic acid 4-(6-alkoxybenzooxazol- 2-yl)-3-hydroxyphenyl ester )為配位基，與過渡金屬銅及鈀配位形成無機液晶，所得之化合物皆以1H、13C-NMR及元素分析鑑定，並以DSC、偏光顯微鏡及POWDER X-RAY鑑定其液晶相。 此系列配位基皆具有N相，碳鏈長度大於6 (n = 6 ~ 12)時出現SmC相，銅錯合物亦都具有N相，碳鏈長度為12時才出現SmC相；鈀錯合物僅短碳鏈(n = 1,4)時才出現N相。二價銅離子與鈀離子皆為平面四邊形配位，造成此現象的原因應與金屬離子與配位基之間鍵長的差異有關。此系列化合物皆有化合物單晶結構，並亦對配位基及錯合物做螢光發光測試。 系列二為具有兩個benzoxazole結構之有機分子，並分別做了碳鏈長度(n = 6 ~ 16)與碳鏈根數(R = 2 ~ 6)的變化，希望能得到盤狀及桿形的分子結構，並形成液晶相，但是由DSC及偏光顯微鏡鑑定之後發現所有化合物皆為結晶相，顯示分子間吸引力大於碳鏈擾動的能力，無論碳鏈根數多寡及碳鏈長度，皆無法形成液晶相。另外亦對此系列化合物做螢光發光測試，討論側鏈根數及位置對發光效率的影響。 In this thesis, we report the synthesis, characterization and mesomorphic properties of two novel series of new mesogenic derivatives based on benzoxazole structure. In serie one , this synthesis, characterization, and mesomorphic properties of a new type of transition metal complexes 1a-1b derived from benzoxazoles 2 as core group are reported. These metal complexes were obtained by the reactions of 6-alkoxynaphthalene-2-carboxylic acid and 4-(6-dodecyloxy benzooxazol-2-yl)-3-hydroxyphenyl esters. The metal complexes were obtained by reaction of benzoxazoles 2 and copper (II) or palladium acetate in refluxing ethanol. All compounds were characterized by 1H, 13C-NMR spectroscopy and elemental analysis. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimeter (DSC) and polarization optical microscope. All compounds with shorter chains (n = 0, 1, 4, 6, 7, 8, 10, 12) exhibited nematic (N) and/or smectic C (SmC) phases, as expected for rod-like molecules. For copper(II) compounds 1a with shorter chains (n = 0, 1, 4, 6, 7, 8, 10) nematic phase was observed only, whereas those compounds having longer carbon chains (n = 12) smectic C phase was also observed at lower temperatures. However, palladium(II) complexes formed nematic phases with short chains (n = 1, 4) only. The difference in the mesomorphic properties observed by compounds 1a and 1b was probably attributed to the geometry at the metal center. Although the Cu2+ ions and Pd2+ ions are both square planar geometries, but the difference of bond length between metal center and ligand is the major effect of mesomorphic behavior. The fluorescent properties of these compounds were also examined. In serie two,we designed and characterized a series of new type of organic molecule 3 ~ 6 derived from two benzoxazoles with two to six side chains. These compounds were prepared by the ring closure reaction of 4,4'-Bis[(3,4,5-trialkoxybenzylidene)amino]biphenyl-3,3'-diol in the presence of lead(Ⅳ) acetate. All compounds were characterized by 1H, 13C-NMR spectroscopy and elemental analysis. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimeter (DSC) and polarization optical microscope. All compounds with two(n = 16) to six side chain(n = 6 ~ 16) exhibited crystal phase, indicate that the interaction between molecules are more larger than the side chain flexibility, no matter how many side chain does the molecule have. The fluorescent properties of these compounds were also examined. |
