College of Sciences, Chemistry Department, Taibah University, Yanbu 30799, Saudi Arabia.
Ibn al-Nafis Secondary School, Yanbu Industrial, Yanbu 46455, Saudi Arabia.
Molecules. 2019 Nov 25;24(23):4293. doi: 10.3390/molecules24234293.
Schiff base liquid crystals, known as [4-(hexyloxy)phenylimino)methyl]phenyl palmitate (), [4-(hexyloxy)phenylimino)methyl]phenyl oleate () and [4-(hexyloxy)phenylimino)methyl]phenyl linoleate (, were synthesized from palmitic, oleic, and linoleic natural fatty acids. The prepared compounds have been investigated for their thermal and optical behavior as well as phase formation using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Molecular structures of all studied compounds were confirmed via elemental analysis, FT-IR, H NMR, and C NMR. Smectic phase is the observed mesophase for all compounds; however, their type and range depend upon the terminal alkanoate chains attached to the phenyl ring. Computational calculations, Density functional theory (DFT), energy difference of the frontier molecular orbital (FMOs), as well as the thermodynamic parameters of different molecular configurations isomers were discussed. It was found that the mesophase behavior and the geometrical characteristics were affected by the degree of unsaturation of fatty terminal chains. Furthermore, the geometrical structure of the CH=N linkage plays an important role in the thermal stability and optical transition temperature.
席夫碱液晶，如[4-（己氧基）苯亚氨基）甲基]苯基棕榈酸酯（），[4-（己氧基）苯亚氨基）甲基]苯基油酸酯（）和[4-（己氧基）苯亚氨基）甲基]苯基亚油酸酯（，是由天然脂肪酸棕榈酸、油酸和亚油酸合成的。通过差示扫描量热法（DSC）和偏光显微镜（POM）研究了所制备化合物的热行为和光学行为以及相形成。通过元素分析、FT-IR、H NMR 和 C NMR 确认了所有研究化合物的分子结构。所有化合物均观察到层状相，但它们的类型和范围取决于连接到苯环上的末端烷酸链。讨论了计算计算、密度泛函理论（DFT）、前沿分子轨道（FMOs）的能量差以及不同分子构型异构体的热力学参数。结果表明，介相行为和几何特征受脂肪酸末端链不饱和程度的影响。此外，CH=N 键的几何结构在热稳定性和光跃迁温度方面起着重要作用。
