Abstract:
In this communication, we would like to show two recent examples in our group in which we exploit the confined nanospaces purposedly created in two very different self-assembled structures to selectively host specific molecules.
The first case comprises tubular nanostructures with custom-tailored pores, which are assembled by coupling two cooperative supramolecular processes of different hierarchy and acting in orthogonal directions. Chiral cyclic tetramers are first formed from 4 monomeric π-conjugated subunits by H-bonding interactions between nucleobase directors. A proper monomer preorganization affords high chelate cooperativities in solution[1] and onto surfaces.[2] When these cyclic species are subjected to a supramolecular polymerization process, helical self-assembled nanotubes are formed via nucleation-growth cooperative mechanisms in organic solvents[3] and in water.[4] Interestingly, the inner pore of these nanotubes can be coated with functional groups of opposite solvophilicity to the external medium, so as to host molecules that show an affinity for this environment.
The second case consists of a novel kind of Zn(II)bis-porphyrin nanocages constructed by imine condensation under thermodynamic control. These cages have two main conformations, depending on the arrangement of the imine bonds, and can host a wide diversity of ditopic nitrogen ligands that fit into its relatively rigid nanocavity. Remarkably, the cage is also an excellent host for fullerene.
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