Mesomorphic behaviour in bent‐shaped molecules with side wings at different positions of a central naphthalene core
Mesomorphic behaviour in bent‐shaped molecules with side wings at different positions of a central naphthalene core
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DOI：
10.1080/02678290701541538
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发表时间：
2007-08
期刊：
影响因子：
2.2
通讯作者：
Seng-Kue Lee;Yusuke Naito;Lu Shi;M. Tokita;H. Takezoe;J. Watanabe
中科院分区：
文献类型：
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作者：
Seng-Kue Lee;Yusuke Naito;Lu Shi;M. Tokita;H. Takezoe;J. Watanabe
制备了六种弯曲形分子，其中心弯曲核基于 2,7-、1,7-、1,6-、1,3-、1,2- 和 2,3-二羟基萘基团，侧翼含有席夫碱部分和十二烷氧基尾部 N(2,7)、N(1,7)、N(1,6)、N(1,3)、N(1,2) 和 N(2,3)。所有化合物均形成流体近晶中间相，并根据其分子结构讨论了它们的介晶行为和性质。这些化合物分为两类：在其中一个 N(2,7)、N(1,6) 和 N(1,3) 中，弯曲磁芯在侧翼之间的弯曲角度为 120°，而在另一个 N(1,7)、N(1,2) 和 N(2,3) 中，弯曲角度为 60°。第一组中的典型香蕉分子 N(2,7) 形成手性蓝相，显示出两个具有相反旋光度和圆二色性的可区分区域。在电场作用下，手性蓝相转变为强双折射B2相，其具有基本上纯手性的SmCAPA结构。 N(1,3)也形成手性蓝相，但相反，侧翼被不对称取代的N(1,6)形成具有外消旋SmCSPA结构的典型反铁电B2相。另一组的 N(1,2) 和 N(2,3) 呈 U 形，形成传统的 SmA 相。有趣的是，N(1,7) 形成手性蓝相，尽管具有 60° 的小弯曲角。这表明侧翼之间的距离以及弯曲角度对于香蕉形近晶相的形成起着重要作用。
Six bent‐shaped molecules were prepared with central bent cores based on 2,7‐, 1,7‐, 1,6‐, 1,3‐, 1,2‐ and 2,3‐dihydroxynaphthalene groups with side wings containing a Schiff's base moiety and dodecyloxy tail, N(2,7), N(1,7), N(1,6), N(1,3), N(1,2) and N(2,3). All of the compounds form fluid smectic mesophases and their mesomorphic behaviour and properties are discussed in terms of their molecular structure. The compounds are categorized into two groups; in one of them, N(2,7), N(1,6) and N(1,3), the bent cores have a bent angle of 120° between the side wings, whereas in the other, N(1,7), N(1,2) and N(2,3), the bent angle is 60°. The typical banana molecule, N(2,7), in the first group, forms a chiral blue phase that shows two distinguishable domains with opposite optical rotations and circular dichroism. Under an electric field, the chiral blue phase is transformed to strongly birefringent B2 phase which possesses a basically homochiral SmCAPA structure. N(1,3) also forms a chiral blue phase, but, in contrast, N(1,6), where the side wings are asymmetrically substituted, forms a typical antiferroelectric B2 phase with the racemic SmCSPA structure. N(1,2) and N(2,3) of the other group assume a U‐like shape to form a conventional SmA phase. Of interest is the fact that N(1,7) forms a chiral blue phase irrespective of having a small bent angle of 60°. This indicates that the distance between side wings as well as the bent angle plays an important role for the formation of banana‐shaped smectic phases.