Exploring triazine and heptazine based self assembled molecular materials through first principles investigations.

Two-dimensional materials formed from the molecular self assembly of monomers through noncovalent interactions are of great importance in designing complex nanostructures with desired properties. The carbon nitride based heterocyclic systems, triazine and heptazine, are found to be promising candidates for generating various self assembled materials through (N....H) hydrogen bonding. Here, we explored graphyne and graphdiyne-like self assembled structures for carbon nitride materials using the density functional theory calculations. We systematically investigated the monolayer structures, stacked structures in different configurations, as well as the surface assembled structures on the Au(111) surface. In all four different monolayer structures, the monomers interact through the N...H hydrogen bonding. The electronic structure results indicate that the electronic properties in these structures can be tuned through the variation in the length of the acetylinic unit. The minimum energy stacked bilayer structure of triazine based material exactly matches with the experimentally reported structure. Surface assembled studies of the triazine based system show strong interaction between the Au(111) surface and the carbon nitride monolayer. Graphical abstract Self assembled two-dimensional molecular materials as well as the surface assemblies of triazine and heptazine based precursors are computationally investigated.