Constructing low-dimensional molecular networks on metal surfaces

The construction of one- as well as two-dimensional molecular networks confined to surfaces is nowadays considered as a promising alternative to the conventional top-down approach for the design and development of future electronic devices. In the framework of this doctoral thesis, various low-dimensional molecular networks were successfully constructed on different metal surfaces and their structural formation was investigated by a combination of different experimental techniques, including scanning tunneling microscopy, X-ray photoelectron spectroscopy and low-energy electron diffraction. In particular, two main research topics are presented in this doctoral thesis. In the first one, the focus is on the creation of self-assembled molecular networks which are held together by (weak) non-covalent intermolecular interactions (halogen/hydrogen bonding, coordination bonding and vdW forces) on metal surfaces. The emphasis is on examining the interplay of intermolecular and molecule substrate interactions with respect to the structural formation of molecular networks. Moreover, the impact of the number and position of functional endgroups attached to the precursors on the resulting intermolecular interactions was studied. The second topic deals with the on-surface synthesis of polymer networks. The aim is to obtain robust molecular networks on metal surfaces with improved chemical and physical properties. Two chemical concepts were employed for the polymer formation: Ullmann coupling and protecting group chemistry. Moreover, the influence of different metal substrates on the outcome of the Ullmann coupling reaction was also investigated. Thus, the results presented in this doctoral thesis are expected to considerably contribute to the ongoing nanotechnological revolution in materials science.