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叠电荷转移（CT）复合晶体为研究对象。在这种晶体中，由于极性分子的触发器运动，预计会出现介电响应。我们制备了几种具有圆盘状极性受体的CT配合物，如TCPA（四氯眼酸酐）。在某些晶体中，受体在高温相的旋转运动随着温度的降低而逐步停止，而在低温相中，晶体对称性转变为极性空间群。利用极性供体组分制备了一些新的CT配合物。

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.