Loska Barbara, Arakawa Yuki, Merkel Katarzyna
Institute of Materials Engineering, Faculty of Science and Technology, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland.
Department of Applied Chemistry and Life Science, Graduate School of Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi, Japan.
Materials (Basel). 2025 Apr 26;18(9):1971. doi: 10.3390/ma18091971.
In this study, we employed density functional theory (DFT), a standard method in quantum chemistry, to investigate the structural intricacies of thioether-linked naphthalene-based liquid-crystal dimers. The theoretical analysis included the calculation of the molecular bend angle, a crucial factor influencing the formation of the twist-bend nematic (N) phase, as well as other molecular parameters such as transition dipole moments, bond lengths, and bond energies. These calculations allowed for the determination of the probable conformations and the computation of their vibrational spectra, which are essential for interpreting experimental spectra. Connecting these insights, we identified stable conformations and observed differences in the spectra between the conventional nematic (N) and N phases. The combined DFT calculations and infrared absorbance measurements allowed us to investigate the structure and intermolecular interactions of molecules in the N and N phases of the dimers. Notably, significant changes in average absorbance were detected in the experimental spectra in the N phase. During the transition from the N phase to the N phase, a clear decrease in absorbance for longitudinal dipoles and an increase for transverse dipoles were observed. This phenomenon suggests that longitudinal dipoles are antiparallel, while transverse dipoles are parallel. To verify the influence of nearest-neighbor interactions, DFT calculations were conducted on a system comprising several neighboring molecules.
在本研究中，我们采用了量子化学中的标准方法——密度泛函理论（DFT），来研究硫醚连接的萘基液晶二聚体的结构复杂性。理论分析包括计算分子弯曲角，这是影响扭曲弯曲向列相（N）形成的关键因素，以及其他分子参数，如跃迁偶极矩、键长和键能。这些计算有助于确定可能的构象并计算其振动光谱，这对于解释实验光谱至关重要。综合这些见解，我们确定了稳定的构象，并观察到传统向列相（N）和N相之间光谱的差异。DFT计算与红外吸光度测量相结合，使我们能够研究二聚体在N相和N相中的分子结构和分子间相互作用。值得注意的是，在N相的实验光谱中检测到平均吸光度有显著变化。在从N相转变为N相的过程中，观察到纵向偶极子的吸光度明显下降，而横向偶极子的吸光度增加。这种现象表明纵向偶极子是反平行的，而横向偶极子是平行的。为了验证最近邻相互作用的影响，我们对包含几个相邻分子的系统进行了DFT计算。
