Structural variations of two-dimensional networks of 2,4,6-tris(4-bromophenyl)-1,3,5-triazine on Au(111) surface from solutions

Monolayers of 2,4,6-tris-(4-bromophenyl)-1,3,5-triazine (TBPT) on Au(111) surfaces were formed via solvent evaporation at different temperatures, and the molecular arrangement and intermolecular association type of these monolayers were probed by scanning tunneling microscopy. Intermolecular Br-N interactions were dominant in the phase formed at 70 degrees C (phase A), while phases with dominant Br-Br interactions were observed at higher temperatures, with a further temperature increase leading to dimerization. The additional heating of different monomer assemblies of the phase formed at 80 degrees C in air afforded phase A, which was thus concluded to be the most stable phase. These results suggest that the dimerization or polymerization of TBPT occurs through metastable phases other than phase A and requires fast solvent evaporation.