Yokoyama T, Yokoyama S, Kamikado T, Okuno Y, Mashiko S
National Institute for Materials Science, Nagoya, Japan.
Nature. 2001 Oct 11;413(6856):619-21. doi: 10.1038/35098059.
The realization of molecule-based miniature devices with advanced functions requires the development of new and efficient approaches for combining molecular building blocks into desired functional structures, ideally with these structures supported on suitable substrates 1-4. Supramolecular aggregation occurs spontaneously and can lead to controlled structures if selective and directional non-covalent interactions are exploited. But such selective supramolecular assembly has yielded almost exclusively crystals or dissolved structures 5; the self-assembly of absorbed molecules into larger structures 6-8, in contrast, has not yet been directed by controlling selective intermolecular interactions. Here we report the formation of surface-supported supramolecular structures whose size and aggregation pattern are rationally controlled by tuning the non-covalent interactions between individual absorbed molecules. Using low-temperature scanning tunnelling microscopy, we show that substituted porphyrin molecules adsorbed on a gold surface form monomers, trimers, tetramers or extended wire-like structures. We find that each structure corresponds in a predictable fashion to the geometric and chemical nature of the porphyrin substituents that mediate the interactions between individual adsorbed molecules. Our findings suggest that careful placement of functional groups that are able to participate in directed non-covalent interactions will allow the rational design and construction of a wide range of supramolecular architectures absorbed to surfaces.
实现具有先进功能的基于分子的微型器件需要开发新的有效方法，将分子构建块组合成所需的功能结构，理想情况下这些结构支撑在合适的衬底上[1-4]。如果利用选择性和定向的非共价相互作用，超分子聚集会自发发生并能导致可控结构。但这种选择性超分子组装几乎只产生晶体或溶解结构[5]；相比之下，吸附分子自组装成更大结构[6-8]尚未通过控制选择性分子间相互作用来实现。在此，我们报道了表面支撑的超分子结构的形成，其尺寸和聚集模式通过调节单个吸附分子之间的非共价相互作用得到合理控制。利用低温扫描隧道显微镜，我们表明吸附在金表面的取代卟啉分子形成单体、三聚体、四聚体或延伸的线状结构。我们发现每种结构都以可预测的方式对应于介导单个吸附分子之间相互作用的卟啉取代基的几何和化学性质。我们的研究结果表明，精心放置能够参与定向非共价相互作用的官能团将允许合理设计和构建吸附在表面的各种超分子结构。
