Diazonium-based covalent functionalization of graphitic materials

Molecular self-assembly has been widely used as tool for the modification and functionalization of surfaces, whereby in many cases pristine surfaces like highly-oriented pyrolytic graphite (HOPG) were used as substrates to study supramolecular self-assembly from solution. Scanning probe techniques enable the study of these molecular layers with sub-molecular resolution. Similar to crystallization in bulk, supramolecular self-assembly is known to take place in distinct steps, that is, nucleation, growth and ripening. Thereby, surface defects are believed to play an important role, in particular as nucleation sites. In this context, the De Feyter group recently started to combine covalent and non-covalent approaches to modify graphitic surfaces using covalently bonds, so-called grafted molecules, as surface defects. The overall objective of the project is to investigate the impact of these covalent surface modifications on the 2D crystallization of organic molecules, i.e. how the density of grafted molecules, acting as surface ‘defects’ or ‘seeds’ affects 2D crystallization. The molecular grafting will be performed using an electrochemical protocol, which enables the control of grafting density and allows to use molecules with different functionalities. Additionally, flow-chemistry will be used to study molecular self-assembly under dynamic conditions.