Two-Dimensional Chiral Molecular Networks from Achiral Building Blocks: A Computational Study

This article describes the application of computer simulations to explore the self-assembly of model achiral molecules on a solid surface leading to the creation of chiral overlayers. To that purpose the lattice gas Monte Carlo method is used to trace the spontaneous self-organization of cross- and tripod-shaped molecules which are represented by rigid planar structures comprising interconnected segments. The study focuses mainly on the influence of size and composition of the molecules on the morphology of the resulting superstructures. It is clearly demonstrated that the molecules, although intrinsically achiral, can assembly into globally chiral two-dimensional networks with regular cavities. Our simulations show also how the chiral networks can be obtained via co-assembly with much smaller molecules and how the additive fills the cavities. In this case, the mixed superstructure is further used as a model enantioselective adsorbent whose adsorptive properties are examined by simulating adsorption isotherms of a racemic mixture of a prototype chiral molecule. The results of this part indicate that the achiral molecular building blocks can be used to construct enantioselective surfaces with tunable adsorption properties.