Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Institute of Physics, University of Rostock, Albert-Einstein-Straße 23, 18059 Rostock, Germany.
Molecules. 2019 Aug 20;24(16):3018. doi: 10.3390/molecules24163018.
The synthesis and surface self-assembly behavior of two types of metal-porphyrin dimers is described. The first dimer type consists of two porphyrins linked via a rigid conjugated spacer, and the second type has an alkyne linker, which allows rotation of the porphyrin moieties with respect to each other. The conjugated dimers were equipped with two copper or two manganese centers, while the flexible dimers allowed a modular built-up that also made the incorporation of two different metal centers possible. The self-assembly of the new porphyrin dimers at a solid-liquid interface was investigated at the single-molecule scale using scanning tunneling microscopy (STM). All dimers formed monolayers, of which the stability and the internal degree of ordering of the molecules depended on the metal centers in the porphyrins. While in all monolayers the dimers were oriented coplanar with respect to the underlying surface ('face-on'), the flexible dimer containing a manganese and a copper center could be induced, via the application of a voltage pulse in the STM setup, to self-assemble into monolayers in which the porphyrin dimers adopted a non-common perpendicular ('edge-on') geometry with respect to the surface.
描述了两种类型的金属卟啉二聚体的合成和表面自组装行为。第一种二聚体类型由通过刚性共轭间隔物连接的两个卟啉组成，第二种类型具有炔键连接体，允许卟啉部分相对于彼此旋转。共轭二聚体配备了两个铜或两个锰中心，而柔性二聚体允许模块化构建，这也使得可以掺入两个不同的金属中心。使用扫描隧道显微镜（STM）在单分子尺度上研究了新卟啉二聚体在固-液界面处的自组装。所有二聚体都形成单层，其中分子的稳定性和内部有序度取决于卟啉中的金属中心。虽然在所有单层中二聚体相对于基底表面共面取向（“面向上”），但通过在 STM 装置中施加电压脉冲，可以诱导含有锰和铜中心的柔性二聚体自组装成其中卟啉二聚体相对于表面采用非常见垂直（“边缘向上”）几何形状的单层。
