Gupta Sakuntala, Das Partha Pratim, Crispini Alessandra, Scarpelli Francesca, Borbone Fabio, Centore Roberto
Department of Physics, Raiganj University, Raiganj, Uttar Dinajpur, Pin-733134, W.B., India.
Bhagilata High School (H.S.), Bhagilata, Kantore, Raiganj, Uttar Dinajpur, Pin-733156, W.B., India.
Acta Crystallogr C Struct Chem. 2022 Nov 1;78(Pt 11):647-652. doi: 10.1107/S2053229622010105. Epub 2022 Oct 24.
The phase behaviour of 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzonitrile, CHN, 1, has been examined. This compound has two different solid phases, denoted I and II, and exhibits thermotropic liquid-crystalline behaviour, with a remarkable interval of stability of the mesophase between the lower melting solid phase (75 °C) and the isotropization temperature (247 °C). The crystal and molecular structures of solid phase I have been determined at 173 K. The cyclohexyl rings both adopt the chair conformation and are equatorially substituted. The packing of 1 in the crystalline state is driven by the antiparallel arrangement of cyano dipoles with the formation of close contacts involving the strong cyano acceptor and weak aromatic C-H or aliphatic C-H donors. The crystal packing is discussed and compared with X-ray diffraction data in the liquid-crystalline state. The combination of thermal analysis, optical polarizing microscopy and X-ray diffraction analysis suggests that the mesophase is a partially ordered smectic phase. The lamellar structure of the mesophase is retained in crystalline solid phase II obtained by cooling the liquid-crystalline phase.
已对4-[反式-4-(反式-4-丙基环己基)环己基]苯甲腈（CHN，1）的相行为进行了研究。该化合物有两种不同的固相，分别记为I和II，并表现出热致液晶行为，在较低熔点的固相（75°C）和各向同性温度（247°C）之间，中间相具有显著的稳定区间。已在173K下测定了固相I的晶体和分子结构。环己基环均呈椅式构象且为平伏取代。1在晶体状态下的堆积是由氰基偶极的反平行排列驱动的，形成了涉及强氰基受体和弱芳香族C-H或脂肪族C-H供体的紧密接触。讨论了晶体堆积并与液晶态的X射线衍射数据进行了比较。热分析、光学偏光显微镜和X射线衍射分析相结合表明，中间相是部分有序的近晶相。通过冷却液晶相得到的结晶固相II中保留了中间相的层状结构。
