An interesting approach towards the control of the organization of shape-persistent macrocycles is the adsorption of the molecules from solution to the surface of highly ordered pyrolytic graphite (HOPG) to form ordered monolayers. Ultimately, these 2D structures may provide a tool for epitaxially induced supramolecular 3D structures.
Indeed, oligo-alkyl substituted macrocycles can be adsorbed at the solution-HOPG interface and forms a highly-ordered and stable monolayer on the HOPG (001) surface. High-resolution scanning tunneling microscopy (STM) images show clearly two-dimensional structures of the macrocycles.
Moreover, oligo-alkyl substituted macrocycles with additional binding sites allow the coadsorption of the rings and appropriate guest molecules (here: C60).