由3,3’-biphenol或4,4’-biphenol衍生及1,3,4-oxadiazole或1,3,4- thiadiazole衍生之液晶材料

Novel Isomers of Organic Mesogens Derived from Two Different Isomeric Biphenol Derivatives and New Organic Mesogens Derived from 1,3,4-oxadiazole or 1,3,4- thiadiazole Derivatives

黃致瑋(Chih-wei Huang)

指導教授 ： 賴重光

國立中央大學/理學院/化學系/碩士(2012年)

摘要

第ㄧ部分

主要探討內容為成功的設計出以 3,3’-biphenol/4,4’-biphenol 衍生之一系列對稱性的同分異構物，並利用 IR、TGA、POM、DSC、XRD、UV、PL 等儀器做化學與物理性質的鑑定。其中分別以4,4''-bis((E)-benzylideneamino)biphenyl-3,3''-diol/3,3''-bis((E)-benzylideneamino)biphenyl-4,4''-diol 做為主體架構，並融入酯類官能基延伸拉長共軛系統合成 1a、1b，與兩支烷氧基的 1c、1e 及四支烷氧基的 1d、1f。再進一步利用合環反應合成出含有 bisbenzoxazole 雜環結構的化合物 2a 到 2f。除了討論同分異構物之間的液晶行為差異之外，另外針對雜環結構的部分做量子產率。
系統中以桿狀液晶分子為設計目標，所有具有液晶行為之分子皆以 N 相、SmC 相堆疊。當所合成之化合物與其同分異構物相比時，在 1a 到 1f 的部分，以 3,3’-biphenol 衍生物之液晶相溫度範圍的表現上較 4,4’-biphenol 衍生的化合物來的廣；而 2a 到 2f 的部分，則是以 4,4’-biphenol 的衍生物優於 3,3’-biphenol 衍生的化合物。其中化合物 2a 到 2f 的量子產率於 ΦF = 0.12 - 0.37 之間。

第二部分

成功的合成出以 quinoxaline 為主體，同時結合 1,3,4-oxadiazole/ 1,3,4-thiadiazole 雜環結構之盤狀液晶分子，並探討置換氧、硫原子對於液晶行為之影響。利用 TGA、POM、DSC、XRD、UV、PL 等儀器做化學與物理性質的鑑定。
系列二中，含有 oxadiazole 結構的化合物 3 除了 n = 8 不具液晶行為之外，剩下的 n = 10, 12, 14, 16 皆具有 Colh 液晶相。其中 n = 10 的化合物在溫度降低時，會轉變為 Colr 液晶相。而含有 thiadiazole 結構的化合物 4 則是依碳鏈長短有 crossover 的情況。在 n = 8, 10, 12 時，液晶分子為 Colr 液晶相。隨著側鏈基長度增加至 n = 14, 16 時，則轉變成 Colh 相。
在 UV、PL 的部分，發現化合物 3、4 的吸放光性質受 quinoxaline 的結構而有所牽制。量子產率於 ΦF = 0.27 - 0.33 之間。

關鍵字

液晶 ； 桿狀液晶 ； 盤狀液晶

並列摘要

Part I

A new type of 3,3’-biphenol/4,4’-biphenol isomer derivatives exhibiting mesomorphic properties were synthesized and their mesomorphic properties examined. All compounds were characterized by 1H and 13C-NMR spectroscopy. Their mesomorphic properties were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and powder x-ray diffraction (XRD). These molecules have two ester linkages (1a, 1b, 2a, 2b), two (1c, 1e, 2c, 2e), and four alkoxy sidechains (1d, 1f, 2d, 2f). The compounds have been synthesized by Schiff base from 1a to 1f. Then others have been synthesized by cyclization of benzoxazole from 2a to 2f.
All of compounds which were shown mesophase formed nematic (N) and/or smectic C (SmC) phase. Crystallographic analysis of 1b revealed that both intermolecular π−π interactions and intramolecular H-bonds were attributed to the formation of mesophases in such system.

Part II

Novel derivatives combined quinoxaline and 1,3,4-oxadiazole/ 1,3,4-thiadiazole structures exhibiting mesomorphic properties were synthesized and their mesomorphic properties examined. All compounds were characterized by 1H and 13C-NMR spectroscopy. Their mesomorphic properties were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and powder x-ray diffraction (XRD). These molecules have 1,3,4-oxadiazole 3 and 1,3,4-thiadiazole 4 exhibiting columnar phases were reported. We changes of alkoxy chains and oxygen/sulfur atoms to contrast with each other. The formation of columnar phases was strongly sensitive to central heteroatoms and/or their positions incorporated.

並列關鍵字

mesophase ； liquid crystal ； bisbenzoxazole ； oxadiazole ； thiadiazole

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