应力释放诱导的酞菁钴转子阵列

利用低温扫描隧道显微镜研究了酞菁钴(CoPc)分子在Cd(0001)表面上形成的自组装单层和转子阵列.在低温生长的酞菁钴分子单层中发现了应力诱导的3种空位结构:单分子空位、两分子空位和三分子空位.研究发现高温退火会导致结构相变:3种空位结构转变为均匀分布的单分子空位阵列.特别有趣的是,在每个单分子空位内部都存在一个酞菁钴转子.在液氮温度下(78 K),酞菁钴转子围绕着空位中心发生偏心转动;在液氦温度下(4.7 K),转子被冻结在空位的边缘上.

Stress Release-Induced Cobalt Phthalocyanine Rotor Array

It is very important to study the artificial molecular motors or rotors, not only for grasping of movement laws of molecular motors, but also for the understanding of the microscopic driving mechanisms of molecular motors. In the natural world, however, most molecular motors work near the interface or surface. Thus it will be more practical to study the molecular motors or rotors on the solid surface in contrast with the precious work. In this paper, the adsorption and self-assembly of cobalt phthalocyanine (CoPc) on Cd(0001) surface have been investigated by low temperature scanning tunneling microscopy. By low temperature growth, it has been found that there are three kinds of randomly distributed vacant structures in the CoPc monolayer:single-molecule vacancy, two-molecule vacancy and three-molecule vacancy. It has been observed that annealing at room temperature causes spontaneous phase separation:the above three vacant structures are transformed into uniformly distributed single-molecule vacancy arrays. Of particular interest, it is found that there is a CoPc rotor which is inside each single-molecule vacancy. At the temperature of liquid nitrogen (78 K), the mobile CoPc performs the off-center rotation inside the cavity; at liquid helium temperature (4.7 K), the rotors is frozen at the edge of the vacancy. The above results provide a new idea for the large-scale preparation of nano-rotating arrays.