含有1,3,4-oxadiazole、isoxazole及pyrazole結構之多雜環桿狀液晶材料

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题名:	含有1,3,4-oxadiazole、isoxazole及pyrazole結構之多雜環桿狀液晶材料
作者:	吳冠儀;Wu,Kuan-Yi
贡献者:	化學學系
关键词:	液晶;雜環;heterocyclic;isoxazole;pyrazole;1,3,4-oxadiazole;pyridine
日期:	2016-07-13
上传时间:	2016-10-13 12:40:40 (UTC+8)
出版者:	國立中央大學
摘要:	本篇論文主要在介紹具有雜環之結構液晶。所有化合物經由1H-NMR、13C-NMR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)來觀測相種類及熱微差掃描分析儀(DSC) 測量相變化時之溫度與熱焓值，最後以變溫粉末X光繞射儀(XRD) 確認相的種類，並運用單晶結構之討論，來解釋化合物的排列及其作用力。在第一部分中，合成出含oxadiazole雜環之diketone化合物2a，另外在其OH基團引入一條烷氧鏈合成化合物2b。並將化合物2合環成異雜環化合物1a、1b、1c以及1d。其中化合物2b、1b為具有N相及SmC相之液晶分子，而化合物1c為具有SmA相之液晶分子。利用成功養出的2a及1c單晶結構了解其分子間作用力與排列情形，並模擬出分子在液晶相時的排列及藉由XRD所得的數據經過理論計算，進一步得知化合物2b、1c在液晶相中的排列情形。在第二部分中，合成出以pyridine為中心硬核，兩端為isoxazole雙雜環之化合物3b；兩端為isoxazole、oxadiazole異雜環化合物3a及isoxazole、pyrazole異雜環化合物3c。其中化合物3a、3b為具有N相及SmC相之液晶分子，而化合物3c為具有SmA相及SmC相之液晶分子。探討雜環種類對於液晶的影響並觀察到澄清點最高的是含有pyrazole雜環的化合物3c且其液晶相範圍最廣、規則度也最高。 ;The 1,3,4-oxadiazoles, isoxazoles and pyrazoles are often considered as one of the most important structures among numerous heterocyclic compounds. These heterocyclic compounds were recently found to exhibit novel mesomorphism due to their varieties in structures and/or known chemistry. Better mesomorphic behavior was attributed to their unsaturation and/or more polarizable nature. 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. In the first part, two new series of mesogenic bisheterocyclic derivatives containing 1,3,4-oxadiazoles and isoxazoles 1ad were described. A dimeric correlated structure induced by Hbonds was observed in the crystal lattice, which was favorable to the formation of mesophases. All compounds 12 exhibited N/SmC, SmA phases, as expected for linearshaped molecules. All compounds 1 have higher clearing temperatures and wider ranges of mesophases than those of their precursors 2, which might be attributed to have higher dipoles polarized by two heterocyclic rings in 2. In the second part, three new series of heterocyclic structures 3ac are prepared, characterized, and their mesomorphic properties investigated. Derivatives 3a exhibited N/ smectic C mesophases; 3b exhibited N/ smectic C mesophases; 3c exhibited smecticA/ C mesophases. The best mesomorphic behavior formed in 3c might be attributed to stronger intermolecular interactions and higher polarization induced in pyrazoles 3c.
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