As one of the most commonly explored classes of supramolecular capsules, there is a vast body of literature on the design and molecular engineering of MOCs. The relatively high strength and directionality of metal-ligand bonds, predictable coordination geometries of transition metal ions, and innumerable combinations of components that can be incorporated into functional ligand scaffolds make MOCs one of the most versatile and useful classes of molecular capsules. As a result, coordination cages have been investigated for wideranging applications in catalysis, 55 molecular separations, sensing, stabilisation of reactive species, and in biomedical applications, with a multitude of reviews written over the years, a small selection of which the reader is directed to for more detailed discussion.