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首页> 外文期刊>Journal of structural chemistry >STRUCTURAL AND THERMODYNAMIC CONSEQUENCIES OF THE INTERACTION OF CONFORMATIONAL DEGREES OF FREEDOM OF AZOMETHINES IN THE NEMATIC PHASE
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STRUCTURAL AND THERMODYNAMIC CONSEQUENCIES OF THE INTERACTION OF CONFORMATIONAL DEGREES OF FREEDOM OF AZOMETHINES IN THE NEMATIC PHASE

机译：氮杂相中构氮自由度构象度相互作用的结构和热力学后果

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摘要

The interaction of the conformational degrees of freedom of azomethines in the nematic phase, which is induced by electronic donor-acceptor properties of the terminal substituents of the benzylideneaniline core is studied. These degrees of freedom related to the rotation angles φ_k around the bonds between the substituent and the aniline ring (φ_1) and also between the CH=N bridge and the aniline ring (φ_2) are characterized by the parameters Q_k = 〈cos_2φφ_k〉. It is found that the interaction of these degrees of freedom is manifested in the linear dependence Q_2(Q_1). Within the phenomenological theory the effect of this interaction on changes δ_k in the Q_k values during the nematic liquid crystal–isotropic liquid phase transition is revealed along with the temperature T_(NI) and character of this transition. The derivation of previously established empirical dependences T_(NI)(Q_k) is presented in the presence of direct and indirect steric effects of side substituents affecting the Q_k values. A diverse combination of δ_k signs in the nematic phase, which is a prerequisite for the conformational polymorphism of the nematic phases of azomethines, is shown.
机译：研究了由亚苄基苯胺核心的末端取代基的电子供体-受体特性诱导的向列相中甲亚胺在构象自由度上的相互作用。这些自由度与围绕取代基和苯胺环之间的键（φ_1）以及CH ＝ N桥和苯胺环之间的旋转角φ_k（φ_2）有关，其特征在于参数Q_k ＝＆cos_2φφ_k＆。发现这些自由度的相互作用体现在线性相关性Q_2（Q_1）中。在现象学理论中，这种相互作用对向列液晶-各向同性液相转变过程中Q_k值的变化δ_k的影响以及温度T_（NI）和这种转变的特征得以揭示。在存在影响Q_k值的侧取代基的直接和间接空间效应的情况下，提出了先前建立的经验依赖性T_（NI）（Q_k）的推导。显示了向列相中δ_k符号的多种组合，这是偶氮甲亚胺向列相构象多态性的前提。

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