Liquid crystalline macrocycles containing phenylpyrimidine unitsElectronic supplementary information (ESI) available: the procedures and analytical data for all compounds and a table with selected bond distances and bond angles of the crystal structure of compound C are available as supplementary da
Liquid crystalline macrocycles containing phenylpyrimidine unitsElectronic supplementary information (ESI) available: the procedures and analytical data for all compounds and a table with selected bond distances and bond angles of the crystal structure of compound C are available as supplementary da
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含有苯基嘧啶单元的液晶大环化合物可提供电子补充信息 (ESI)：所有化合物的程序和分析数据以及包含化合物 C 晶体结构的选定键距和键角的表格可作为补充资料提供
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
C. Tschierske
中科院分区：
文献类型：
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作者：
Bernhard Neumann;T. Hegmann;C. Wagner;P. Ashton;R. Wolf;C. Tschierske
在高稀释条件下，通过大环化反应合成了几种不同的由2-苯基嘧啶或5-苯基嘧啶组成的大环液晶，其两端由聚醚或烷基链连接。刚芯的性质对形成的液晶相有很大的影响。所有的2-苯基嘧啶副环烷均为向列相，而5-苯基嘧啶系列衍生物仅形成近晶a相。这种行为与传统的灾难性苯基嘧啶液晶有关，但中间相在大环中是强烈稳定的。聚醚链与烷基链的交换导致了显著的中间相稳定性，而增加间隔长度则降低了中间相稳定性。讨论了分子结构对这些化合物中间相行为影响的原因，包括核的预组织和化学上不同分子部分的微分离。
Several different macrocyclic liquid crystals consisting of two calamitic 2-phenylpyrimidine or 5-phenylpyrimidine units connected at both ends by polyether or alkyl chains have been synthesised by macrocyclisation reactions under high dilution conditions. The nature of the rigid core has a strong impact on the liquid crystalline phases formed. All 2-phenylpyrimidine paracyclophanes show nematic phases, whereas for the series of the 5-phenylpyrimidine derivatives smectic A-phases are exclusively formed. This behaviour is related to conventional calamitic phenylpyrimidine liquid crystals, but the mesophases are strongly stabilised in the macrocycles. An exchange of polyether chains by alkyl chains leads to significant mesophase stabilisation, whereas increasing the spacer length reduces mesophase stability. Pre-organization of the calamitic cores and micro-segregation of chemically distinct molecular parts are discussed as reasons for the observed effects of molecular structure on the mesophase behaviour of these compounds.