Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 10: On-surface Polymerization

CPP 10.1: Hauptvortrag

Montag, 16. März 2015, 15:00–15:30, H 0105

Formation mechanisms of covalent nanostructures — •Jonas Björk — Department of Physics, Chemistry and Biology, IFM, Linköping University, Linköping, Sweden

The on-surface reactions underlying the formation of covalent nanostructures are in many cases fundamentally different from their wet chemistry analogues. Furthermore, their mechanisms are often intractable from experiments due to short-lived intermediate and transition states, and to make use of the true potential of this approach we need to understand the factors controlling the on-surface reactions. Here, it will be demonstrated how density functional theory can be used as a powerful tool for gaining insight into the mechanisms of these reactions. Firstly, we will discuss the on-surface Ullmann coupling, where halogen-substituted molecules are used as the basic building blocks. The key aspects of this reaction scheme will be scrutinized for simple model systems, but we will also discuss the effect of increasing the complexity towards more realistic systems. In particular, it will be examined how metal adatoms affect the different reaction processes, as these have shown to play a pivotal role in experiments.

Secondly, we will briefly discuss the mechanisms of other coupling schemes presented during the last years, with focus on the homo-coupling of terminal alkynes. This reaction has a completely different mechanism than that of the on-surface Ullmann coupling, with the coupling preceding the release of any side-products. Furthermore, the on-surface chemistry of alkynes is extremely rich, with several possible reaction products depending on molecule and/or surface.