Steering the Surface-Confined Self-Assembly of Multifunctional Star-Shaped Molecules

Abstract

Directing the self-assembly (SA) of small organic molecules into low-dimensional porous patterns is a versatile method for the bottom-up fabrication of flat nanomaterials with controllable architecture and functions. However, the rational synthesis of the self-assembled monolayers (SAMs) requires carefully choosing the building blocks with a proper size, shape, and functionalization scheme. Among the molecular bricks used for this purpose, especially promising are the (N-hetero)aromatic star-shaped molecules equipped from three to six electronegative functional groups, providing anisotropic in-plane intermolecular interactions. Therefore, in this work, the surface-confined SA of tripodal polytopic molecules was investigated using lattice Markov chain Monte Carlo (MCMC) computer simulations in the canonical ensemble. Specifically, the simulated building blocks were equipped with terminal interaction centers providing short-range directional interactions and represented on a flat triangular lattice in a simplified but credible way. By altering the number and intramolecular position of sticky sites attached to these rigid tectons, we observed the emergence of various supramolecular constructs, including isolated well-shaped aggregates, twodimensional (2D) open porous networks, and a series of hierarchically organized floral phases, which were classified according to their morphological properties. Our theoretical findings may be helpful in predicting the SA of π-aromatic multifunctional tripod molecules on close-packed crystalline surfaces and relevant to the scanning tunneling microscopy (STM) laboratory experimentalists seeking new linkers for the construction of novel surface-supported supramolecular constructs with a predefined topology.