It is noted that topologically similar architectures can often be obtained from different building blocks. The tetrapyridyl, square planar Pd(II) motif, for example, is structurally analogous to the tetracarboxylate dicopper(II) paddlewheel node and these can be used to form geometrically isostructural assemblies (Fig. ). Thus, the choice of particular structural features can be dictated by restrictions imposed by the intended application without wholesale redesign of the assembly topology. Most commonly, MOCs are assembled from a single type of ligand, referred to as homoleptic cages, and a single type of metal ion/node (homometallic or homonuclear). To increase the structural complexity of these systems, design principles have been developed to form low-symmetry cages (Fig. ). This include heteroleptic (mixed-ligand) MOCs 31 (Fig. ) from the self-assembly of ligand mixtures (a process referred to as integrative self-assembly) and heterometallic cages 33 incorporating different metal ions (Fig. ). Additionally, investigations into directing the orientation-selective assembly of low-symmetry ligands, 35 that would otherwise form a mixture of isomeric MOCs, have been reported (Fig. ). 36 Fig. Low-symmetry coordination cages can be prepared via different strategies. R groups omitted from SCXRD structures for clarity.