Catenation and encapsulation induce distinct reconstitutions within a dynamic library of mixed-ligand Zn4L6 cages

Abstract

Two new Zn₄L₆ cages composed of diamine subcomponents containing either naphthalene diimide (NDI) or porphyrin moieties are described. Their structural differences allow these cages to exhibit distinct interactions with different chemical stimuli, yielding different supramolecular products. The electron-poor NDI subunits of the first cage were observed to thread through electron-rich aromatic crown-ether macrocycles, forming mechanically-interlocked species up to a [3]catenane, whereas the porphyrin ligands of the second cage interacted favourably with C₇₀, causing it to be bound as a guest. When mixed, the two cages were observed to form a dynamic combinatorial library (DCL) of seven constitutionally distinct mixed-ligand Zn₄L₆ cages. The DCL was observed to reconstitute in opposing ways when treated with either the crown ether or C₇₀: the electron-rich macrocycle templated the formation of heteroleptic catenanes, whereas C₇₀ caused the DCL to self-sort into homoleptic structures.