Synthesis and liquid crystalline behavior of azulene-based liquid crystals with 6-hexadecyl substituents on each azulene ring
Synthesis and liquid crystalline behavior of azulene-based liquid crystals with 6-hexadecyl substituents on each azulene ring
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DOI：
10.1016/j.tet.2010.08.012
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发表时间：
2010-10-16
期刊：
影响因子：
2.1
通讯作者：
Ohta, Kazuchika
中科院分区：
文献类型：
--
作者：
Nakagawa, Kosuke;Yokoyama, Takahiro;Ohta, Kazuchika
以二（6-十六烷基-2-奥基）乙炔（2b）为原料，在Co-2（CO）8催化下进行环三聚反应，合成了六（6-十六烷基-2-奥基）苯（1b）。采用差示扫描量热法（DSC）、偏光显微镜（POM）和X射线衍射（XRD）技术研究了1b、2b和6-十六烷基-2-苯基奥（3b）的介晶行为，并与6-辛基衍生物1a、2a和3a的介晶性质进行了比较。外周侧链中碳原子数的增加使1b、2b和3b的各向同性化温度分别下降56.9 ℃、33 ℃和23.6 ℃。此外，除了化合物3b外，其相变行为随着外围链数目的增加而变化，并且随着晶体-中间相转变温度的降低而变化。结果表明，化合物1b在未经处理的玻璃衬底上以Col（hd）介晶相自发地形成单畴垂直排列，这将在分子材料的器件制备中有很大的应用前景。(C)2010年由Elsevier Ltd.出版
Hexakis(6-hexadecyl-2-azulenyl)benzene (1b) has been synthesized by Co-2(CO)8-catalyzed cyclotrimerization reaction of bis(6-hexadecyl-2-azulenyl)acetylene (2b). The mesomorphic behaviors of 1b, 2b, and 6-hexadecyl-2-phenylazulene (3b) were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) techniques and their mesomorphic properties were compared with those of their 6-octyl derivatives 1a, 2a, and 3a. Increase of the number of carbon atoms in the peripheral side chains drops the isotropization temperatures of 1b, 2b, and 3b by 56.9 degrees C, 33 degrees C, and 23.6 degrees C, respectively. Additionally, the phase-transition behavior varied with increase of the number of the peripheral chains, as well as decrease of the crystalline-mesophase transition temperatures, except for compound 3b. As the results, spontaneous monodomain homeotropic molecular alignment was revealed by compound 1b in its Col(hd) mesophase on non-treated glass substrate, which would be attracted to the application for the device fabrication of molecular materials. (C) 2010 Published by Elsevier Ltd.