Akutagawa Tomoyuki, Koshinaka Hiroyuki, Sato Daisuke, Takeda Sadamu, Noro Shin-ichiro, Takahashi Hiroyuki, Kumai Reiji, Tokura Yoshinori, Nakamura Takayoshi
Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
Nat Mater. 2009 Apr;8(4):342-7. doi: 10.1038/nmat2377. Epub 2009 Feb 8.
Molecular rotation has attracted much attention with respect to the development of artificial molecular motors, in an attempt to mimic the intelligent and useful functions of biological molecular motors. Random motion of molecular rotators--for example the 180 degree flip-flop motion of a rotatory unit--causes a rotation of the local structure. Here, we show that such motion is controllable using an external electric field and demonstrate how such molecular rotators can be used as polarization rotation units in ferroelectric molecules. In particular, m-fluoroanilinium forms a hydrogen-bonding assembly with dibenzo[18]crown-6, which was introduced as the counter cation of Ni(dmit)(2) anions (dmit(2-) = 2-thioxo-1,3-dithiole-4,5-dithiolate). The supramolecular rotator of m-fluoroanilinium exhibited dipole rotation by the application of an electric field, and the crystal showed a ferroelectric transition at 348 K. These findings will open up new strategies for ferroelectric molecules where a chemically designed dipole unit enables control of the nature of the ferroelectric transition temperature.
关于人工分子马达的发展，分子旋转已备受关注，旨在模仿生物分子马达的智能且有用的功能。分子转子的随机运动——例如旋转单元的180度翻转运动——会导致局部结构的旋转。在此，我们表明这种运动可通过外部电场进行控制，并展示了此类分子转子如何用作铁电分子中的极化旋转单元。特别地，间氟苯胺鎓与二苯并[18]冠-6形成氢键组装体，二苯并[18]冠-6作为[Ni(dmit)₂]⁻阴离子（dmit²⁻ = 2-硫代-1,3-二硫杂环戊烯-4,5-二硫醇盐）的抗衡阳离子被引入。间氟苯胺鎓的超分子转子在施加电场时表现出偶极旋转，且该晶体在348 K时呈现铁电转变。这些发现将为铁电分子开辟新策略，其中化学设计的偶极单元能够控制铁电转变温度的性质。
