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首页> 外文期刊>Chemistry: A European journal >Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization
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Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization

机译：咪唑基棒状离子液晶的自组装：从层状到胶束组织的转变

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By using aryl-amination chemistry, a series of rodlike 1-phenyl1H- imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) has been prepared. The number and length of the C-terminal chains (at the noncharged end of the rodlike core) and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified and the influence of these structural parameters on the mode of self-assembly in LC phases was investigated by polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For the single-chain imidazole derivatives nematic phases (N) and bilayer SmA_2 phases were found, but upon increasing the number of alkyl chains the LC phases were lost. For the related imidazolium salts LC phases were preserved upon increasing the number and length of the C-terminal chains and in this series it leads to the phase sequence SmA-columnar (Col)-micellar cubic (Cuby1/Pm3n). Elongation of the N-terminal chain gives the reversed sequence. Short Nterminal chains prefer an end-to-end packing of the mesogens in which these chains are separated from the C-terminal chains. Elongation of the N-terminal chain leads to a mixing of N- and C-terminal chains, which is accompanied by complete intercalation of the aromatic cores. In the smectic phases this gives rise to a transition from bilayer (SmA_2) to monolayer smectic (SmA) phases. For the columnar and cubic phases the segregated end-to-end packing leads to core-shell aggregates. In this case, elongation of the N-terminal chains distorts core-shell formation and removes Cub_1 and Col phases in favor of single-layer SmA phases. Hence, by tailoring the length of the N-terminal chain, a crossover from taper-shaped to polycatenar LC tectons was achieved, which provides a powerful tool for control of self-assembly in ILCs.
机译：通过使用芳基胺化化学，制备了一系列棒状的基于1-苯基1H-咪唑的液晶（LC）和相关的基于咪唑鎓的离子型液晶（ILC）。修改了C端链的数量和长度（在棒状核的不带电荷的末端）和N端链的长度（在ILC中的咪唑单元上），并且这些结构参数对模式的影响通过偏光显微镜，差示扫描量热法和X射线衍射研究了LC相中自组装的机理。对于单链咪唑衍生物，发现了向列相（N）和双层SmA_2相，但是随着烷基链数量的增加，LC相消失了。对于相关的咪唑鎓盐，通过增加C端链的数量和长度可以保留LC相，并且在该序列中，它导致形成SmA-柱（Col）-胶束立方（Cuby1 / Pm3n）的相序列。 N-末端链的延长给出了相反的序列。短的N端链倾向于介晶的端到端堆积，其中这些链与C端链分开。 N-末端链的延长导致N-和C-末端链的混合，这伴随着芳族核的完全插入。在近晶相中，这导致从双层（SmA_2）过渡到单层近晶（SmA）相。对于柱状和立方相，端到端的隔离堆积导致了核壳聚集体。在这种情况下，N端链的延伸会扭曲核-壳的形成，并去除Cub_1和Col的相，有利于单层SmA相。因此，通过调整N端链的长度，可以实现从锥形到多类别LC构造的交叉，这为控制ILC中的自组装提供了强大的工具。

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