Alrefaee Salhah H, Ahmed Hoda A, Khan Mohd Taukeer, Al-Ola Khulood A, Al-Refai Hanaa, El-Atawy Mohamed A
Department of Chemistry, College of Science, Taibah University, Yanbu 30799, Saudi Arabia.
Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt.
Polymers (Basel). 2022 Jan 23;14(3):456. doi: 10.3390/polym14030456.
Herein, a new homologues series of fluorinated liquid crystal compounds, , 4-(((4-fluorophenyl)imino)methyl)-2-methoxyphenyl 4-alkoxybenzoate were synthesized and its mesomorphic properties were investigated both experimentally and theoretically. The synthesized compounds were characterized by elemental analyzer, NMR, and FT-IR spectroscopy to deduce the molecular structures. The differential scanning calorimetry was employed to examine mesophase transitions whereas the polarized optical microscopy was used to identify the mesophases. The obtained results revealed that the purely nematic phase observed in all terminal side chains. All homologues showed to possess monotropic nematic mesophases except the derivative exhibits enantiotropic property. The optimized geometrical structures of the present designed groups have been derived theoretically. The experimental data was explained using density functional theory computations. The estimated values of dipole moment, polarizability, thermal energy, and molecule electrostatic potential demonstrated that the mesophase stability and type could be illustrated. Binary phase diagram was constructed and addressed in terms of the mesomorphic temperature range and obtained polymorphic phases. It was found that incorporation of the terminal F-atom and lateral CHO group influence both conformation and steric effect in pure and mixed states. The absorption and fluorescence emission spectra of fabricated films were recorded to elucidate the impact of terminal side chain on photophysical properties of synthesized liquid crystal. It was noted that the increase of terminal side chain length lead to reduction of optical band gap, whereas charge carrier lifetime increases.
在此，合成了一系列新的氟化液晶化合物，即4-(((4-氟苯基)亚氨基)甲基)-2-甲氧基苯基4-烷氧基苯甲酸酯，并对其介晶性能进行了实验和理论研究。通过元素分析仪、核磁共振和傅里叶变换红外光谱对合成的化合物进行表征，以推导其分子结构。采用差示扫描量热法研究中间相转变，同时利用偏光显微镜识别中间相。所得结果表明，在所有末端侧链中均观察到纯向列相。除衍生物表现出互变性质外，所有同系物均显示具有单向性向列中间相。从理论上推导了当前设计基团的优化几何结构。利用密度泛函理论计算对实验数据进行了解释。偶极矩、极化率、热能和分子静电势的估计值表明，可以说明中间相的稳定性和类型。构建了二元相图，并根据介晶温度范围和获得的多晶相进行了讨论。发现末端氟原子和侧向醛基的引入会影响纯态和混合态下的构象和空间效应。记录了制备薄膜的吸收光谱和荧光发射光谱，以阐明末端侧链对合成液晶光物理性质的影响。值得注意的是，末端侧链长度的增加导致光学带隙减小，而电荷载流子寿命增加。
