Cybotaxis dominates the nematic phase of bent-core mesogens: a small-angle diffuse X-ray diffraction study
Cybotaxis dominates the nematic phase of bent-core mesogens: a small-angle diffuse X-ray diffraction study
复制标题
DOI：
10.1039/c0sm00745e
复制
发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Samulski, Edward T.
中科院分区：
文献类型：
--
作者：
Francescangeli, Oriano;Vita, Francesco;Samulski, Edward T.
基于非线性2，5-二(对羟基苯基)-1，3，4-恶二唑(ODBP)单元的弯芯介晶的新的随温度变化的X射线衍射数据使得对这类液晶中的超分子结构有了一致的解释。高温阶段的趋胞性的有力证据解释了小角度四点模式，并对先前的X射线衍射解释提出了质疑。我们发现，这些数据可以用倾斜的、弯曲的中生元(BCMS)的分层排列来令人满意地解释。我们还观察到了温度诱导的偏斜的趋胞体向正常的趋胞体的演化，其中BCMS的长轴与层的起伏是垂直的。我们的X射线衍射解释与核磁共振数据是一致的，核磁共振数据显示了ODBP向列相的双轴性。
New temperature dependent X-ray diffraction (XRD) data on the bent-core mesogens based on the nonlinear 2,5-bis(p-hydroxyphenyl)-1,3,4-oxadiazole (ODBP) unit enable a consistent interpretation of the supramolecular structure in this class of liquid crystals. Strong evidence for cybotaxis in the high temperature phase explains the small-angle four-spot pattern and calls into question prior XRD interpretations. We find that the data can be satisfactorily explained by skewed cybotaxis, a stratified arrangement of tilted, bent-core mesogens (BCMs). We also observe the temperature-induced evolution of skewed cybotaxis to normal cybotaxis-strata wherein the long axes of the BCMs are normal to the layer fluctuations. Our XRD interpretation is compatible with the NMR data that exhibit biaxiality in the nematic phase of ODBP mesogens.