Alamro Fowzia S, Ahmed Hoda A, Bedowr Noha S, Khushaim Muna S, El-Atawy Mohamed A
Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia.
Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt.
Polymers (Basel). 2022 Mar 21;14(6):1256. doi: 10.3390/polym14061256.
In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (-CH=N-N=CH-), namely ((1E,1'E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared compounds were determined using elemental analysis, NMR, and FT-IR spectroscopy. The mesophase transitions were detected by differential scanning calorimetry (DSC), and the mesophases were identified using polarized optical microscopy (POM). The results indicated that the derivative with the shortest length () was purely nematogenic, while the other homologues ( and ) possessed SmC mesophases. The optimal geometrical structures of the investigated group were derived theoretically. The estimated results demonstrated that all homologues were mesomorphic, and their type depended on the length of the terminal chains. Computations based on density functional theory (DFT) were used to explain the experimental data. The calculated dipole moment, polarizability, thermal energy, and molecular electrostatic potential all showed that it was possible to predict the mesophase type and stability, which varied according to the size of the molecule.
在本研究中，合成了一系列带有双偶氮甲碱中心键（-CH=N-N=CH-）的新型液晶化合物，即（（1E，1'E）-肼-1,2-二亚基双（亚甲基））双（4,1-亚苯基）二链烷酸酯（），并对其介晶相和热性能进行了理论和实验研究。使用元素分析、核磁共振和傅里叶变换红外光谱确定了所制备化合物的分子结构。通过差示扫描量热法（DSC）检测介晶相转变，并使用偏光显微镜（POM）鉴定介晶相。结果表明，最短链长的衍生物（）为纯向列型，而其他同系物（和）具有SmC介晶相。从理论上推导了所研究基团的最佳几何结构。估计结果表明，所有同系物都是介晶的，其类型取决于末端链的长度。基于密度泛函理论（DFT）的计算用于解释实验数据。计算得到的偶极矩、极化率、热能和分子静电势均表明，可以预测介晶相类型和稳定性，其会根据分子大小而变化。
