Polar and chiral mesophases formed by m-terphenyl derived bent-core molecules with lateral F-substituents
作者:Gert Dantlgraber、Christina Keith、Ute Baumeister、Carsten Tschierske
DOI:10.1039/b705499h
日期:——
A new series of bent-core molecules based on fluorinated terphenyl cores has been synthesized. The influence of the position of the polar fluorine substituent on the mesomorphic properties was studied. The mesophases under discussion were investigated by means of polarizing microscopy, differential scanning calorimetry, X-ray diffraction as well as electrooptical experiments. Depending on the position of the fluorine substituent, polar smectic or columnar mesophases were formed. Remarkable textures could be observed for the smectic phases. For some compounds regular arrays of dots can be found which are interpreted as layer deformation on a macroscopic scale. Of special interest is the coexistence of helical filaments and a dark conglomerate texture with domains of opposite handedness found for one of the polar smectic phases. The smectic phases under investigation show antiferroelectric switching behaviour, whereas the rectangular columnar phases do not show polar switching.
我们合成了一系列基于氟化三联苯核心的新型弯曲核心分子。研究了极性氟取代基的位置对介形性质的影响。我们通过偏光显微镜、差示扫描量热仪、X 射线衍射以及电光实验对所讨论的介相进行了研究。根据氟取代基的位置不同,形成了极性涂抹或柱状介相。在涂抹相中可以观察到显著的纹理。对于某些化合物,可以发现规则的点阵列,这可以解释为宏观尺度上的层变形。特别值得注意的是,在其中一种极性胶凝相中发现了螺旋状细丝和带有反手结构域的暗色胶凝纹理共存的现象。研究中的漆膜相表现出反铁电转换行为,而矩形柱状相则没有表现出极性转换。