The structural complexity of self-assembled metal–organic
capsules can be increased by incorporating two or more different ligands
into a single discrete product. Such complexity can be useful, by
enabling larger, less-symmetrical, or more guests to be bound. Here
we describe a rational design strategy for the use of subcomponent
self-assembly to selectively prepare a heteroleptic cage with a large
cavity volume (2631 Å3) from simple, commercially
available starting materials. Our strategy involves the initial isolation
of a tris(iminopyridyl) PdII3complex1, which reacts with tris(pyridyl)triazine ligand2to form a heteroleptic sandwich-like architecture3. The tris(iminopyridyl) ligand within3serves as a
“brace” to control the orientations of the labile coordination
sites on the PdIIcenters. Self-assembly of3with additional2was thus directed to generate a large
PdII12heteroleptic cuboctahedron
host. This new cuboctahedron was observed to bind multiple polycyclic
aromatic hydrocarbon guests simultaneously.