【作者】 张齐贤；

【导师】 陈彬；

【作者基本信息】 东北师范大学 ， 物理化学， 2011， 博士

【摘要】 咪唑类离子液晶是离子液晶的一种。咪唑类离子液晶具有液晶的自组装有序性和咪唑盐的高离子导电性,可作为取向性离子导电材料。同时,由于此类化合物多具有高度有序的近晶层列相,可作为制备贵金属纳米材料的模板和稳定剂,在新型纳米材料的合成方面也具有一定价值。偶氮类化合物是常用染料的一类,也是重要的液晶、光、电功能性材料。咪唑改性的偶氮苯类液晶化合物,能够增加偶氮苯化合物液晶相转变的温度范围,拓展其在光信息存储和光化学装置方面的应用。目前,对于偶氮苯咪唑离子液晶的研究还处于起步阶段。本论文合成了系列新型偶氮苯咪唑离子液晶,对于咪唑类离子液晶的深入研究具有重要意义;同时,对于拓展偶氮苯在光信息存储、光控分子取向、分子开关等方面的应用具有重要意义。本文合成了系列单咪唑取代的对硝基偶氮苯离子液晶(C_n和D_n),并通过不同长度的柔性链将对硝基偶氮苯和咪唑连接起来,制备了系列新型离子液晶材料。本文合成了系列咪唑双取代的新型偶氮苯离子液晶(DC_n),在此基础上进一步研究了阴、阳离子对材料液晶性能的影响。本文合成了系列咪唑乙烯取代的小分子偶氮苯离子液晶(C_n),并对其性能进行了详细表征。本文还以咪唑双取代的偶氮苯分子作为正电荷,以柠檬酸离子保护的金纳米为负电荷,通过静电吸引层层组装成功能性多层膜,并通过紫外可见光谱和循环伏安法检测多层膜的生长过程,研究了咪唑取代的偶氮苯基元在多层膜中的特殊作用。更多还原

【Abstract】 Ionic liquid crystals (ILCs) are a class of liquid-crystalline compounds containing anions and cations. Among liquid crystalline materials, the investigation of ionic liquid crystalline materials based on imidazolium salts is one of the most important and interesting liquid crystalline compounds. Ionic liquids show many useful properties such as very low vapor pressure, high thermal stability, non-flammability, high chemical stability, high ionic conductivity and wide electrochemical window, which may serve widely as a new generation of solvents in synthesis, catalysis, separation, and electrochemistry. Among the known ILCs, imidazolium salts are the most frequently studied, in which imidazoles can form ionic liquids and ionic liquid crystals by quaternization. The ionic interaction of imidazolium tends to stabilize lamellar mesophases, which shows great potential as ordered reaction media that can impart selectivity in reactions by ordering reactants. Incorporation of imidazolium ion functionalities into the paraffin side-chain terminated 4-nitroazobenzene derivatives could lead to a new series of liquid crystalline materials for research and industrial applications. We expected that the ionic interaction of imidazolium group could stabilize the mesophase of the azobenzene moiety over a wide temperature range, such azobenzene derivatives with a broad mesophase range are promising in high density optical data storage and photochemical devices.A novel series of compounds with different counteranions, 1-{[4-(4-nitrophenylazo) phenyloxy]} alkyl-3-methyl-1H-imidazol-3-ium bromide salts (C_n, n=3,6,10) and tetraflu oroborate salts (D_n, n=3,6,10) were synthesized by the incorporation of imidazolium group into the paraffin side-chain terminated 4-nitroazobenzene derivatives, respectively. A new series of ILCs, 1-(4-(4-nitrophenylazo)phenyloxy) vinyl-3-methyl-1H-imidazol-3-ium bromide salts(Cn, n=6, 10) were synthesized. In order to further investigate the effects of the ionic interaction on the mesophase of azobenzene liquid crystals, we incorporated two imidazolium groups into a azobenzene moieties via different length alkyl chains. Their chemical structures were determined by 1H NMR, 13C NMR, UV spectroscopy and elemental analysis. Our studies revealed that ionic interaction between imidazolium salts was the driving force for the formation of the monolayer smectic C, which enhances the thermal stability of the smectic state.Vinylimidazolium ion group-functionalised nitrophenylazo with different length of alkyl chains were reported in detail. We described the synthesis of these compounds and the characterization of their thermotropic liquid crystalline properties, moreover, the influence of ionic interaction between imidazolium salt on the mesomorphic properties was also explored. These results showed that the attached vinylimidazolium units induced the self-assembly of ILs and the occurrence of liquid crystalline phases. The introduction of vinylimidazolium group enhanced the thermal stability of the smectic state, which played an important role in forming the smectic layer structure.The ordered multilayers of azobenzene moiety with two symmetric substitution imidazolium ion groups (DC_n) and Au-cit nanoparticles were fabricated on the ITO substrate through the electrostatic layer-by-layer assembly technique. the growing process of multilayer growth was examined by UV–vis spectroscopy and cyclic voltammetry. We explored the role of azobenzene moiety in multilayers. The ordered multilayers are promising in high density optical data storage and photochemical devices.更多还原