Monte Carlo simulations of the self-assembly of hierarchically organized metal-organic networks on solid surfaces

The coordination-driven self-assembly of two-dimensional (2D) supramolecular architectures is a convenient method of rational construction of one-atom-thick nanomaterials with desired topology, intriguing physico-chemical properties and high cognitive value. In this work, we use coarse-grained Monte Carlo (MC) computer simulations to study the self-assembly of functional bridging ligands with mononuclear metal centers on a triangular lattice. Particularly, we focus on the role of anisotropic, reversible ligand -> metal coordinate bonds in the bottom-up formation of hierarchically organized metal-organic networks composed of star-shaped and rod-like linkers (representing real organic molecules) and trivalent metal atoms. In our model pi aromatic ligands were modeled in a simplified way as a collection of flat, rigid, and interconnected segments with properly encoded short-ranged interactions. Depending on the composition of the investigated overlayers, we observed the spontaneous formation a cascade of openwork (co)crystals with a hierarchical structure, controllable chirality and scalable morphological properties like porosity, connectivity, density, etc. Our theoretical findings can pave the way for the experimental fabrication of the novel surface-confined metal-organic networks (SMONs) in which anisotropic coordinate bonds play a decisive role.