Supramolecular heterostructures formed by sequential epitaxial deposition of two-dimensional hydrogen-bonded arrays

Abstract

Supramolecular heterostructures are formed by growing sequential layers of bi- and mono-component two-dimensional molecular arrays stabilized by hydrogen bonding. The heterostructures are formed on hexagonal boron nitride by depositing cyanuric acid/melamine (CA.M) followed by terephthalic acid (TPA) or trimesic acid (TMA) and imaged using atomic force microscopy under ambient conditions with resolution approaching 0.1 nm. A clear epitaxial arrangement is observed between these layers having intrinsically distinct symmetries and lattice constants, which for TMA/CA.M corresponds to a (root3 x root3)R30o phase, while TPA forms rows with a molecular separation that matches the CA.M period. Structures calculated using classical molecular dynamics are in excellent agreement with the orientation, registry and dimensions of the epitaxial layers. Calculations confirm that van der Waals interactions provide the dominant contribution to the adsorption energy and registry of the layers.