End functionalised liquid crystalline bent-core molecules and first DAB derived dendrimers with banana shaped mesogenic units
End functionalised liquid crystalline bent-core molecules and first DAB derived dendrimers with banana shaped mesogenic units
复制标题
DOI：
10.1039/b415910a
复制
发表时间：
2005-01-01
影响因子：
--
通讯作者：
Tschierske, C
中科院分区：
文献类型：
--
作者：
Kardas, D;Prehm, M;Tschierske, C
合成了一系列新的端羧基非对称双核化合物及其苄酯和五氟苯基酯。对于大多数五氟苯基酯和氟原子位于烷氧基链邻位的苄基酯，观察到不同类型的柱状带状相（Col（r）P（A）和Col（ob）P（A））和极性近晶SmCPA相。柱状相和近晶相都表现出反铁电开关行为。基于这些功能化的香蕉形分子的第一个例子的两亲性的双核分子与终端1-酰基氨基丙烷-2，3-二醇单元和DAB衍生的树枝状聚合物的第一代以及第二代已经合成，并已研究了它们的物理性质。无论是二醇封端的双核心分子，也没有树枝状聚合物显示任何电光响应。具有长脂肪链的树枝状聚合物以及两亲物形成非极性双层近晶相，而具有较短链的树枝状聚合物组织成具有2D晶格的中间相（Col）。这似乎是氢键在外围的非晶核心单元是不利的极性近晶相的形成。
New series of non-symmetric bent-core compounds with a terminal carboxylic function as well as its benzyl esters and pentafluorophenyl esters have been synthesised. For most pentafluorophenylesters and for a benzylester with fluorine atoms in the ortho positions to the alkoxy chain different types of columnar ribbon phases (Col(r)P(A) and Col(ob)P(A)) and a polar smectic SmCPA phase have been observed. Both the columnar and the smectic phases show antiferroelectric switching behaviour. Based on these functionalised banana-shaped molecules the first example of an amphiphilic bent-core molecule with a terminal 1-acylaminopropane-2,3-diol unit and DAB derived dendrimers of the first as well as the second generation have been synthesised and their physical properties have been investigated. Neither the diol-terminated bent-core molecule nor the dendrimers show any electrooptical response. Dendrimers with long aliphatic chains as well as the amphiphile form non-polar bilayer smectic phases, whereas dendrimers with shorter chains organise into a mesophase with a 2D lattice ( Col). It seems that hydrogen bonding at the periphery of the bent-core units is unfavourable for the formation of polar smectic phases.