BN-Patterning of Metallic Substrates through Metal Coordination of Decoupled Borazines.

We report on the synthesis of pyridine-terminated borazine derivatives, their molecular self-assembly as well as the electronic properties investigated on silver and copper surfaces by means of scanning tunneling microscopy and X-ray photoelectron spectroscopy. The introduction of pyridine functionalities allows us to achieve distinct supramolecular architectures with control of the interdigitation of the molecules by surface templating. On silver surfaces, the borazine derivatives arrange in a dense-packed hexagonal structure through van der Waals and H-bonding interactions, whereas on Cu(111), the molecules undergo metal coordination. The porosity and coordination symmetry of the reticulated structure depends on the stoichiometric ratio between copper adatoms and the borazine ligands, permitting an unusual three-fold coordinated Cu-pyridyl network. Finally, spectroscopy measurements indicate that the borazine core is electronically decoupled from the metallic substrate. We thus demonstrate that BNC-containing molecular units can be integrated into stable metal-coordination architectures on surfaces, opening pathways to patterned, BN-doped sheets with specific functionalities, for example, regarding the adsorption of polar guest gases.