Designing banana-shaped liquid crystals without Schiff's base units: m-terphenyls, 2,6-diphenylpyridines and V-shaped tolane derivatives
作者:Dong Shen、Siegmar Diele、Gerhard Pelzl、Ina Wirth、Carsten Tschierske
DOI:10.1039/a808275h
日期:——
This paper reports attempts to obtain (anti)ferroelectric switchable achiral banana-shaped molecules without Schiff's base units. For this purpose we have synthesized novel V-shaped molecules consisting of rigid angular central units [1,3-disubstituted benzene, 2,7-disubstituted naphthalene, 1,3-diphenylbenzene, 2,6-diphenylnitrobenzene, 2,6-diphenylpyridine, 1,3-bis(phenylethynyl)benzene, 1-phenyl-3-(phenylethynyl)benzene] connected via ester linkages to two rigid cores (1,4-disubstituted benzenes, biphenyls, 2-phenylpyrimidines, phenylbenzoates). Most compounds have rather high melting points. Only molecules with seven aromatic rings show liquid crystalline properties. Two-dimensional modulated smectic phases (rectangular columnar phases) were found for molecules with phenylbenzoate rigid units. Intercalated fluid smectic phases were detected for the corresponding 2-phenylpyrimidine derivatives. For the first time in the case of banana-shaped molecules a nematic phase was observed for a 2′-nitro-m-terphenyl-4,4″-diyl bisbenzoate. However, none of the synthesized compounds exhibit the typical texture of the (anti)ferroelectric switchable mesophases, known from the Schiff's base derivatives.
这篇论文报告了在没有施夫碱单元的情况下,获得可切换的反铁电和铁电非手性香蕉形状分子的尝试。为此,我们合成了新型的V形分子,这些分子由刚性角形中心单元(1,3-二取代苯、2,7-二取代萘、1,3-二苯基苯、2,6-二苯基硝基苯、2,6-二苯基吡啶、1,3-双(苯乙炔)苯、1-苯基-3-(苯乙炔)苯)通过酯连接物连接至两个刚性核心(1,4-二取代苯、联苯、2-苯基吡啶、苯基苯甲酸酯)。大多数化合物的熔点相当高。只有七个芳香环的分子显示出液晶特性。具有苯基苯甲酸酯刚性单元的分子观察到二维调制的层状相(矩形柱状相)。相应的2-苯基吡啶衍生物检测到了夹层流体层状相。在香蕉形状分子的情况下,首次观察到2′-硝基-m-三苯基-4,4″-二苯甲酸酯的涡旋相。然而,合成的化合物中没有任何显示出施夫碱衍生物所知的典型(反)铁电可切换介相的纹理。