Five three-rings azomethine/ester derivatives, namely, 4-(hexyloxy)phenylazomethine phenyl benzoate (1), 4ʹ-(4”-hexyloxy)phenylazomethine phenyl-3-methoxy benzoate (2), 4ʹ-(4”-hexyloxy)phenylazomethine phenyl-4-methoxy benzoate (3), 4ʹ-(4”-hexyloxy) phenylazomethine phenyl-3,4-dimethoxy benzoate (4), and 4ʹ-(4”-hexyloxy) phenylazomethine phenyl-3,5-dimethoxy benzoate (5), were synthesised and their mesophase behaviour investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). Their molecular structures were elucidated via FT-IR, ¹ H-NMR and elemental analysis. All the compounds (1–5) were found to be enantiotropically monomorphic possessing SmA phase with high-temperature range and high thermal stability. Computational studies revealed that all compounds investigated are non-co-planar. The dipole moment of each derivative is a function of the number of the methoxy groups; it decreases in the order 2 ˃ 5 ˃ 1 ˃ 3 > 4. On the other hand, the molecular polarisability is dependent on the number of the methoxy groups, which is accordingly dependent on the molecular aspect ratio. The results of the FMO calculations revealed that the HOMO orbitals energies of the methoxy-substituted compounds 2–5 are lower compared to the laterally neat compound, 1. Finally, the effect of introducing the methoxy group in different position and number affect the charge distribution that could explain the behaviour of the enhanced mesophases.

五种三环的偶氮甲碱/酯衍生物，分别是4-（己氧基）苯基偶氮甲碱苯基苯甲酸酯（1），4ʹ-（4”-己氧基氧基）苯基azo甲氨酸苯基-3-甲氧基苯甲酸酯（2），4ʹ-（4“-己氧基）苯偶氮甲基苯基-4-甲氧基苯甲酸苯基酯（3），4ʹ-（4“-己氧基氧基）苯基azo甲氨酸苯基-3,4-二甲氧基苯甲酸酯（4）和4ʹ-（4”-己氧基氧基）苯azo甲氨酸苯基-3,5-二甲氧基苯甲酸酯（5）合成，并通过差示扫描量热法（DSC）和偏振光学显微镜（POM）研究了它们的中间相行为。通过FT-IR，¹  H-NMR和元素分析阐明了它们的分子结构。所有化合物（1 - 5）被发现是具有高温范围和高热稳定性的SmA相的对映体单晶。计算研究表明，所有研究的化合物都是非共面的。每种衍生物的偶极矩是甲氧基数的函数。它以2 × 5 × 1 × 3> 4的顺序递减。另一方面，分子极化率取决于甲氧基的数目，因此取决于分子的长径比。FMO计算结果表明，与侧向纯化合物1相比，甲氧基取代的化合物2–5的HOMO轨道能量较低。。最后，在不同位置和数量引入甲氧基的效果影响电荷分布，这可以解释增强中间相的行为。