Azacalixphyrin nanostructures

Azacalixphyrins are used as building blocks to elaborate nanostructures with different shapes depending on the nature of the N-substituents. In this work, the formation of nanoribbons from N-alkyl azacalixphyrin 4, and nanodonuts from the N-aryl analogue 5, is presented and rationalized by molecular dynamics (MD) simulations. Indeed, MD revealed different modes of intermolecular interactions (defines as nodes-and-trails and nodes-and-thorns models) according to the nature of the N-substituents. Nanoribbons based on 4 results from the stackings of the azacalixphyrin cores along the vertical direction generate the nodes, while the van der Waals interactions between the N-C(8)H17 aliphatic chains generate the trails among the nodes along the ribbon. On the other hand, azacalixphyrin 5 self-assemblies into a nanodonut shape, in which the macrocyclic cores (nodes) stack along the horizontal plane while the 3,4,5-trimethoxyphenyl groups (thorns) point along the vertical direction towards the solvent where they establish a network of p-p interactions among their aromatic portions and H-bond interactions among the CH3O-groups and the solvent molecules, respectively.