Calamitic Mesogens Formed by Heterocyclic Isoxazole, Benzoxazole and 1, 3, 4-Oxadiazole

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题名:	Calamitic Mesogens Formed by Heterocyclic Isoxazole, Benzoxazole and 1, 3, 4-Oxadiazole
作者:	陳慧珊;Chen,Hui-shan
贡献者:	化學學系
关键词:	液晶;Liquid Crystal
日期:	2015-07-15
上传时间:	2015-09-23 10:43:27 (UTC+8)
出版者:	國立中央大學
摘要:	系列一主要合成設計出含醛官能基之雜環結構，利用Schiff Base反應得桿狀液晶2b，並另外合出與其對照之具N及SmC液晶相化合物2a、具SmA及SmC之2c，觀察有無OH基團、硬核增加與否對液晶相所造成之影響；參考與2c結構相似之文獻可模擬三者分子排列，硬核增加能提供作用力使澄清點上升，OH基團能提供氫鍵使分子排列規則；搭配變溫IR可鑑定特定基團，藉由升降溫觀察peak的變化，發現從固態到液態的過程中，分子的作用力的確有所變化。接著2b、2c進行合環反應得1b、1c，isoaxazole與benzoxazole均能提供作用力的來源，使1b具有N及SmC相、1c為SmA相；將兩者單晶結構相比發現1b 之isoxazole提供作用力使其在低溫時能呈SmC之規則排列，相對1c雖排列也是整齊卻至多只能使分子朝同方向排列的層狀結構(SmA)；試著以imine延長整體結構得1d，由單晶看到軟硬端重疊所以不論碳鏈長短才能有亂度大之N相，另外也有好的熱穩定度。系列二成功合成含isoxazole與oxadiazole之三雜環對稱結構1e，具SmC相，並成功培養出單晶結構，與實驗室眾多相同/異雜環相比得一重要資訊：兩isoxazole對於分子排列之影響力比oxadiazole大，然而在液晶行為上的表現並無太大差別，1e也有好的熱穩定度。 ;In the first series, a new system of isoxazole containing function group of aldehyde, performed reaction of Schiff Base then exhibition mesomorphic properties was synthesize and examined. 2b exhibited SmC phase. The control group 2a with N、SmC phase and 2c exhibited SmC phase. Results indicated that increasing the rigid cores would raise the isotropic temperatures and increasing the OH functional group would supply hydrogen bonds for molecular arrangement regularity. Using variable temperature IR spectroscopy observed the change of interaction. 1b、1c performed reaction of cyclization exhibited N, SmC and/or SmA phase. 1d was extended from 1b, and exhibited N phase. Two single crystallographic structures(1b、1d) were determined by X-ray crystallographic analysis. These mesomorphic properties were studied and identified by polarization microscopy, differential scanning calorimetry, and X-ray diffraction methods. In the second series, we succeed to synthesize three heterocyclic symmetric structure, 1e, characterization and their mesomorphic properties investigated. One single crystallographic structures were determined by X-ray crystallographic analysis. Compare with other similar example, results indicated that isoxazole effected upon the molecular arrangement more than 1, 3, 4-oxadiazole but mesomorphic properties were no difference.
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