Self-assemblies of porphyrin-based molecules (tetra-pyridyl-porphyrin (TPyP) and ZnTPyP) on different single-crystal metallic substrates have been investigated using scanning tunneling microscopy (STM) in the ultra high vacuum (UHV) environment. TPyP molecules adsorbed on the Au(111) surface are self-assembled into close-packing islands, in which molecules are linked with each other by hydrogen bonds. However, the novel two dimensional Kagome lattices can be observed after one exposing the sample in electro-beam (see figure 1). We propose the exposure of electron-beam can increase the catalysis of Au atoms existing on the Au(111) surface as lattice gas, and consequently the molecules in the self-assemblies are deprotonated. Careful calculation of the distance between the molecules indicates molecules are linked by the coordination bonds with Au atoms [1]. We have also fabricated Kagome lattices by adding Cu atoms during evaporation of the TPyPs on the Au(111) surface. The Kagome lattices can be obtained on Ag(111) surfaces through co-evaporating Cu atoms with the TPyPs. The Kagome lattice is interesting to scientists due to their distinct frustrated magnetic properties. We hence are trying to introduce the magnetic metal atoms, like iron into the central porphyrin macrocycles, utilizing the direct metalation pathways in UHV systems [2,3].
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