Elaboration of Hydrogen-Bonded 2D Supramolecular Assemblies on Au(111) From Solutions: Toward Naphthalene Tetracarboxylic Diimide–Melamine Nanoporous Networks

Melamine and naphthalene tetracarboxylic diimide (NTCDI) supramolecular assemblies have been elaborated by a solution-based approach on Au(111) and studied by scanning tunneling microscopy (STM). We discuss the role of π-oligomers and H-oligomers in the mechanism of the network formation. Whereas the role of the first seems negligible, thermodynamical considerations establish the key role of the H-oligomers in the network extension in relation with the solvent nature. Density functional theory (DFT) calculations on the networks support the experimental structures. We discuss the influence and advantages of the solution method on the assemblies comparatively to ultrahigh vacuum (UHV) conditions. The NTCDI–melamine network exhibits a honeycomb structure which is obtained for the first time on the Au(111) substrate. The supramolecular mixed network is remarkably robust due to the stabilization from the triple hydrogen bonds established between the neighboring NTCDI and melamine molecules.