Various design principles have been explicated for the targeted formation of MOC structures, often based on commonly recognised polyhedra, such as the Platonic solids (tetrahedron, cube, octahedron etc.), that position ligands on the edges, faces or vertices of these shapes. These include the symmetry interaction, 23 directional bonding and molecular panelling approaches, with several excellent reviews available that cover these design strategies in detail. A subset of these design principles is the concept of sub-component selfassembly, 27 in which the complete ligand scaffold is assembled in situ through dynamic covalent chemistry, such as the condensation of an amine building block with 2-formylpyridine to form bidentate pyridylimine moieties (Fig. ). 28 Fig. In sub-component self-assembly strategies, ligands are formed in situ using DCC.