Structure Formation in 2D Assemblies Comprising Functional Tripod Molecules with Reduced Symmetry

摘要

Surface-confined self-assembly of organic building blocks is a versatile method of creation of low dimensional structures with potential applications in nanotechnology and material engineering. A key factor which often determines morphology of such 2D supramolecular assemblies is the geometry' and functionality of a molecular tecton at play. In this contribution, we use theoretical modeling to predict the structure of adsorbed systems in which tripod molecules with reduced symmetry interact via a short-range anisotropic pair potential. To that end the self-assembly of a tripod molecule with one shortened/elongated arm, adsorbed on a triangular lattice, is modeled using the Monte Carlo simulation method. The probe asymmetric molecule consists of a few interconnected segments, and it is equipped with terminal interaction centers (active segments) with differently assigned interaction directions. Our study focuses on the effect of directionality of intermolecular interactions on the morphology of the resulting supramolecular 2D assemblies. It is demonstrated that a suitable encoding of the interaction directions allows for the creation of largely diversified adsorbed structures including aperiodic porous networks, molecular ladders, strings, ribbons and dispersed aggregates. Main differences and similarities between the findings reported for the asymmetric molecules and their C3-symmetric counterparts are also discussed. The obtained results can be helpful in designing new molecular tectons for controlled on-surface self-assembly and coupling reactions, as they provide useful information on the molecule superstructure relation. This preliminary information can, for example, facilitate screening of molecular libraries to select an optimal molecule able to create low-dimensional structures with predefined properties.