Abstract

The structure and thermal properties of azobenzene derivatives R₁–C₆H₄–N=N–C₆H₄–R₂, where R₁/R₂ = CH₃COO/C₂H₅O (I), CH₂=C(CH₃)COO/C₂H₅ (II), or C₆H₁₃COO/C₂H₅O (III), were studied by differential scanning calorimetry and X-ray diffraction. Compounds I and III form a mesophase (nematic) upon melting, whereas compound II does not produce a mesophase. Compound III is characterized by two high-temperature crystal–crystal phase transitions III_III–III_II–III_I. The low-temperature crystal modification, which is not a precursor of the mesophase, was structurally characterized. The crystal packing of I is stabilized by C−H···π interactions and consists of alternating loosely and closely packed regions. Weak directional interactions that connect the molecules into zigzag chains ensure the structuring of the mesophase of I. The possible structuring pattern of the mesophase of III is discussed.

中文翻译：

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潜在介晶的偶氮苯衍生物R 1 –C 6 H 4 –N = N–C 6 H 4 – R 2（R 1，R 2 = CH 3 COO，C 2 H 5 O; CH 2 = C（CH 3 ）COO，C 2 H 5; C 6 H 13 COO，C 2 H 5 O）

摘要

偶氮苯衍生物R ₁ –C ₆ H ₄ –N = N–C ₆ H ₄ – R ₂的结构和热性质，其中R ₁ / R ₂ = CH ₃ COO / C ₂ H ₅ O（I），CH ₂ = C（CH ₃）COO / C ₂ H ₅（II）或C ₆ H ₁₃ COO / C ₂ H ₅ O（III），通过差示扫描量热法和X射线衍射进行研究。化合物I和III熔融时形成中间相（向列型），而化合物II不产生中间相。化合物III的特征在于两个高温晶型液晶相转变III _III - III _II - III_予。不是中间相前体的低温晶体变体在结构上得到了表征。我的水晶包装通过CH···π相互作用稳定，由交替的松散和紧密堆积的区域组成。将分子连接成锯齿形链的弱方向相互作用确保I的中间相的结构。讨论了III中间相的可能结构模式。