Substrate Effects in the Supramolecular Self-Assembly of 2,4,6-Tris(4-bromophenyl)-1,3,5-triazine on Graphite and Graphene

Two-dimensional self-assembly of star-shaped 2,4,6-tris­(4-bromophenyl)-1,3,5-triazine (BPT) molecule is investigated both on highly oriented pyrolytic graphite (HOPG) and single-layer graphene (SLG) grown on a polycrystalline Cu foil. Scanning tunneling microscopy (STM) reveals that this molecule can form different self-assembling structures on these two different surfaces. On the basis of high-resolution STM images, we find that BPT molecules can form compact and loose assembly patterns with different packing densities on HOPG surface and a porous structure with hexagonal-like cavities on SLG surface. A combination of STM and density functional theory calculations elucidates the interplay of molecule–molecule and molecule–substrate interactions on the assembling behavior on both substrates.