【作者】 余文浩；

【导师】 赵可清；

【作者基本信息】 四川师范大学 ， 环境科学， 2007， 硕士

【摘要】 盘状液晶能自组装成高度有序的六方柱状相,因而具有较高各向异性的载流子迁移速率,其作为有机半导体材料有广泛的应用前景。为了改善其电荷载流子迁移速率,目前对苯并菲盘状液晶的研究工作大多试图通过分子设计,增加分子沿柱轴的有序堆积,以获得稳定的柱状相。常用的方法有利用引入氟代烃链和分子间氢键来锚定盘状液晶分子的柱状相。本文通过分子设计,合成了两类的氟代烃链和酰胺键形成氢键的苯并菲盘状液晶化合物,对其介晶性进行了研究。化合物纯度和结构通过¹H NMR, EA测试和表征。化合物热稳定性通过热重分析（TGA）测定,热致液晶性通过偏光显微镜（POM）和差示扫描量热法（DSC）研究。本文所获得的液晶分子结构与介晶性关系的相关信息,将为液晶材料的分子设计和实际应用打下基础。本文分为四章:1.第一章简要介绍了液晶的基础知识,以及含氟液晶在盘状液晶中的研究状况,并对近几年来利用酰胺键形成的氢键在盘状液晶中的相互作用进行了归纳。2.氟链部分和碳氢部分的微相分离,可有效地促使棒状分子形成近晶相,并稳定液晶相。为了探讨氟效应对盘状分子介晶性的影响,第二章合成了一系列全氟苯甲酸酯链的苯并菲化合物C₁₈H₆(OC_nH_2n+1)₅(OCOC₆H₄C₆F₁₃),以及另外两个相对应系列的不含氟化合物C₁₈H₆(OC_nH_2n+1)₅(OCOC₆H₄OC₅H₁₁), C₁₈H₆(OC_nH_2n+1)₅（OCOC₆H₄C₆H13）,n = 4 9。DSC检测和偏光显微镜观察显示两类化合物都为柱状相热致型液晶(除C₁₈H₆（OC4H9）₅(OCOC₆H₄OC₅H₁₁)外)。含氟化合物与相对应的不含氟化合物比较,其熔点和清亮点上升,柱状相的热稳定性增强。3.在盘状分子中引入分子间氢键来控制盘状液晶分子之间的有序堆积是一种行之有效的方法。特别是通过酰胺键形成分子间氢键来稳定柱状相已被一些研究小组所利用。第三章中合成了三个系列,共十八个有两种不同软链的苯并菲盘状液晶化合物:C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOEt）, C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOBu）,和C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHBu）, n = 4 9。通过差示扫描量热法（DSC）检测和偏光显微镜观察,表明化合物都为柱状相热致型液晶。热重分析（TGA）表明,化合物有较高的热稳定性。结果显示:对于分子中含有酰胺基的苯并菲液晶化合物C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHBu）,与具有同样软链长度的分子中不含酰胺键的化合物系列C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOBu）相比较,前者由于柱内分子间氢键的形成,具有更高的熔点和清亮点。4.第四章引入不同位置的酰胺基,研究其对介晶性的影响。主要合成的是一条尾链带有官能团（酯基或酰胺基）的苯并菲类盘状液晶C₁₈H₆(OC₉H₁₉)₅[O（CH₂）_mCOXBu],X = O、NH,m = 1⁵系列,研究了随着亚甲基数量的增加,即官能团（酯基及酰胺基）的位置外移对化合物介晶性的影响;同时在一条尾链上同时引入酰胺基和羟基,终端羟基之间也能形成氢键作用。在第四章中对强氢键作用对化合物C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHCH₂CH₂OH）,n = 4⁹介晶性的影响也进行了探讨。有机凝胶由于其物理和形态学特性越来越受到关注。在第四章中将对具有相同尾链长度的含酰胺基的苯并菲化合物C₁₈H₆(OC₇H₁₅)₅（OCH₂CONHBu）在不同的有机溶剂中形成凝胶的情况进行初步的研究。更多还原

【Abstract】 Discotic liquid crystals self-assemble to highly ordered hexagonal columnar mesophase （Colho）, exhibit anisotropic high charge carrier mobility and show huge potential application as organic electronic materials. To obtain materials with improved charge carrier mobilities, the thrust of much research on triphenylene based liquid crystals has been to introduce structural modifications designed to increase the columnar ordering in terms of the average length of ordered stacking arrays along the column. Introducing fluorinated chain and hydrogen bonding are elegant method to enhance the attractive interactions between the discotic mesogens. This thesis reported the molecular designing, synthesis and mesomorphism of two series of triphenylene discotic liquid crystals with fluorinated chain or chains contain amide functional groups. The purity and structure characterization of these compounds were carried out with ¹H NMR, EA. Thermal gravimetry analysis （TGA） showed these compounds have good thermal stability. The thermotropic liquid crystal properties were studied through polarizing optical microscopy （POM） and differential scanning calorimetry （DSC）. The structure-property relationship of these molecules was proposed, and it is hopefully to contribute to the molecular designing and practical application of these liquid crystals as new materials.The thesis consists of four chapters:1. Chapter one briefly introduced the fundamental knowledge about liquid crystal materials, then fluorinate discotic liquid crystals in latest years have been studied, and more attention of the thesis have been focused on hydrogen bond stabilized discotic liquid crystals.2. The fluorophobic effect of highly fluorinated alky terminal chain of rod-like molecular can efficiently promote the formation of semctic phase and improve the stability of mesophase. In order to investigate the influence of fluorinated chain on mesomorphism of disctoic molecules, a series of new triphenylene derivatives C₁₈H₆(OC_nH_2n+1)₅(OCOC₆H₄C₆F₁₃), with a perfluorohexylbenzoate side chain and their two series hydrocarbon analogues, C₁₈H₆(OC_nH_2n+1)₅(OCOC₆H₄OC₅H₁₁), C₁₈H₆(OC_nH_2n+1)₅（OCOC₆H₄C₆H13）, n = 4 9, were synthesized in chapter two. Studies of DSC and POM texture observations revealed that these triphenylene derivatives showed enantiotropic hexagonal columnar mesophases (except C₁₈H₆（OC4H9）₅(OCOC₆H₄OC₅H₁₁)). Compared with the hydrocarbon ester chain, the fluorinated ester chain increased the melting points and clearing points, and stabilized the columnar mesophase of triphenylene discogens.3. An elegant method to enhance the attractive interactions between the discotic mesogens is by introducing hydrogen bonding. To obtain stabilized columnar phases amide groups have been used by several research groups. In chapter three, three series with total of eighteen triphenylene discotic liquid crystalline compounds possessing two different kinds of peripheral chains, which are abbreviated as C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOEt）, C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOBu）, and C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHBu）, n = 4 9, were synthesized. Studies of DSC and texture observations by polarized microscope revealed that these triphenylenes show enantiotropic hexagonal columnar mesophase. The TGA showed that all these compounds had good thermal stability up to 300 oC. The results showed that, for compounds C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHBu） and C₁₈H₆(OC_nH_2n+1)₅（OCH₂COOBu）, the former has higher melting and clearing points than the latter due to the intra-columnar intermolecular hydrogen bonding.4. In chapter four, triphenylene discotic liquid crystals with a tail contain function groups-amide or ester C₁₈H₆(OC₉H₁₉)₅[O（CH₂）_mCOXBu],X = O、NH,m = 1⁵, were synthesized. The influence of distance between function group and the triphenylene core on mesomorphism has been discussed. At the same time, the triphenylene derivatives with a tail contain amide and hydroxyl groups, C₁₈H₆(OC_nH_2n+1)₅（OCH₂CONHCH₂CH₂OH） , n = 4⁹ were synthesized. The terminal hydroxyl groups can also form hydrogen bond with each others, and the strong hydrogen bond impact on mesophase is also investigated. Organogels have attracted increasing interest in recent years due to their promising physical and morphological properties. In this thesis different organic solvents were tested for gelation by C₁₈H₆(OC₇H₁₅)₅（OCH₂CONHBu）.5. Chapter 5 gives the summary and conclusion of the thesis.更多还原