For the cases involving enantiopure ligands, metal-organic assembly usually yields a single diastereomer, with diastereoselectivity of the self-assembly process minimally influenced by external variables. Different guestbinding preferences are shown by diastereomeric cages due to variations in the size and enclosure of the cavities or the arrangement of hydrogen bond donors. Nitschke group reported that, by simply changing the solvent, a single enantiopure porphyrin-based ligand was able to self-assemble with octahedral metal ions to form two different diastereomers of a M II 8L6 (MOC 22, M = Zn II or Co II ) cage, with the metal centers taking on a preferred Δ or Λ configuration (Figure ). In acetonitrile, the major diastereomer was assigned as (S)24-L8, with a d.r. of 3.8:1, whereas the diastereomer with opposite metal handedness, (S)24-D8, developed preferentially in nitromethane, with a d.r. of 1:6, which was further confirmed by CD spectroscopic analysis. In the presence of a chiral template guest D-TRISPHAT (G), which possesses a configuration that complements the propeller-shaped pentapyrrole backbone, a truncated rhombohedral structure Zn II 15L6 (MOC-23) was formed exclusively (Figure ), inferred to have a structure similar to its Co II congener. Comparing the average dihedral angle of ~82° (between the pentagonal faces along a common edge), with the dihedral angle of ~88° (between two tetrachlorocatecholate groups of G), stereoselectivity of the cage formation process was confirmed through CD spectroscopic analysis. Although the handedness of the Zn vertices could not be confirmed due to the absence of MLCT (metal-to-ligand charge transfer) transitions, a similar CD spectrum for its Co congener inferred that the Zn vertices possess D handedness. Thus, G not only served as a template to stabilize the otherwise disfavoured Zn II 15L6 but also controlled the enantioselectivity in the self-assembly process. Interestingly, in absence of such chiral modifier, the dodecahedron Zn20L12 (MOC-24) transforms to give a larger Zn30L12 icosidodecahedron (MOC-25) through subcomponent exchange, or an unprecedented pseudotruncated octahedral structure Zn20L8 (MOC-26). Apart from the nature of the subcomponents present in the reaction medium, their concentration can also be used to govern the self-assembly outcome of the system. The selective formation of a Fe12L12 icosahedron, a Fe2L3 helicate and Fe4L4 tetrahedron occurred from the same triazatriangulenium component in CH3CN with the reaction concentrations of 4.4 mM and 2.2 mM, respectively for the icosahedron and helicate. Interestingly, when larger anions like CB11H12 -or B12F12 2-were added to the helicate solution, complete conversion into tetrahedron Fe4L4 was witnessed, where the larger anions act as the templates to bring four cationic ligands together, overcoming inter-ligand Columbic repulsions.