Conformation Analysis of Ferroelectric Liquid Crystals

在本研究中，我们对铁电液晶（FLC）进行了实验和理论构象分析，以了解铁电性的起源和这种新型液晶分子的结构-性质关系。我们合成了具有选择性氘代手性烷基链的FLC样品，并进行了氘核磁共振研究。通过分子轨道（MO）计算分析了液晶相的平均手性链构象.对反铁电液晶分子MHPOBC进行了分子轨道（MO）计算和分子动力学（MD）模拟，以了解其构象性质和晶相弯曲结构形成的原因.该分析得出结论：1）MHPOBC手性链的基本构象特征是由分子内相互作用决定的，2）MHPOBC可以采用两种主要构象，即，线性和弯曲构象，和3）由于分子间空间相互作用，在结晶相中选择弯曲构象。我们还进行了一系列的Monte Carlo（MC）模拟的模型液晶分子（包括珠和Gay-Berne模型分子）。这些研究为我们提供了一个直观的洞察液晶秩序的自发形成的分子机制。

In this study, we have carried out experimental and theoretical conformational analyzes of ferroelectric liquid crystals (FLC) in order to understand the origin of ferroelectricity and the structure-property relationship in this novel class of liquid crystalline molecules.1. we have synthesized a FLC sample with selectively deuterated chiral alkyl chain and performed deuterium NMR study. The results are analyzed by molecular orbital (MO) calculations to give the average chiral-chain conformation in liquid crystalline phases.2. Molecular orbital (MO) calculation and molecular dynamics (MD) simulation have been carried out for an antiferroelectric liquid crystalline molecule MHPOBC to understand its conformational property and the origin of bent structure formation in crystalline phase. This analysis concludes that 1) the essential conformational feature of the chiral chain of MHPOBC is determined by intramolecular interactions, 2) MHPOBC can adopt two major conformations, i.e., linear and bent conformations, and 3) the bent conformation is selected in the crystalline phase as a consequence of intermolecular steric interactions.3. We also carried out a series of Monte Carlo (MC) simulations of model liquid-crystalline molecules (including beads and Gay-Berne model molecules). These studies have provided us with a straightforward insight into the molecular mechanism of the spontaneous formation of liquid crystalline order.