Tailoring Supramolecular Assemblies on a Metal Surface by Specically Functionalized Porphyrins

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The self-assembly behavior of porphyrin derivatives bearing different substituents is investigated on metal surfaces by Scanning Tunneling Microscopy
(STM). Different methods to control the self-assembly process by skillful changes of the molecular substituents are developed. It is shown how one-dimensional wires as well as two-dimensional nanoporous networks can be formed by the same molecular compound depending on the surface coverage. The nanoporous networks can be altered in their pore characteristics and pore-to- pore distances in a controlled way. This is exploited to form a fully self-assembled supramolecular device. The characteristics of the device are studied in detail and it is shown that it can be operated by the tip of an STM. Finally, bimolecular systems are investigated. Here it is shown how the need to balance losses of entropy which is a common factor in all self-assembled networks, can be exploited to direct the self-assembly of such systems to form either separated phases or an intermixed network.