Design of ferroelectricity induced by rotational motion of disc-like polar molecules

本研究以极性组分具有一定动态旋转自由度的混合堆积电荷转移(CT)络合物晶体为研究对象。在这类晶体中，由于极性分子的翻转运动，可能会出现介电响应。我们制备了几种带有盘状极性受体的CT络合物，如四氯苯酸酐(TCPA)。在一些晶体中，随着温度的降低，高温相中受主的旋转运动逐渐停止，而在低温相中，晶体的对称性向极性空间群转变。还利用极性给体组分制备了一些新的CT络合物。

In this study, mixed-stacked charge-transfer (CT) complex crystals in which polar components have a certain degree of freedom of dynamic rotation were targeted. In such crystals, dielectric response is expected to appear due to flip-flop motion of the polar molecules.We prepared several CT complexes with disc-like polar acceptors such as TCPA (tetrachlorophthalic anhydride). In some of the crystals, rotational motion of the acceptor in the high-temperature phase was ceased step-wise at the phase transitions with decreasing temperature, and in the low-temperature phase the crystal symmetry was found to change to a polar space group. Some new CT complexes were also prepared using polar donor components.