Diffusion 1 H NMR measurements were acquired on the isolated samples of cages 1-3 to verify that the assigned peaks for the M4L4 topology correlated with a single assembly in solution (Section S3.4). Additionally, the measured diffusion of the secondary peaks present alongside cage 2 and cage 3 also indicated these components have a single, smaller solvodynamic radius than the major signals from the tetrahedral cages. In cage 2, the major species has a diffusion coefficient of 7.05 × 10 -10 m 2 /s while the minor species signals gave a coefficient of 8.06 × 10 - 10 m 2 /s, indicating the solvodynamic radius of the minor species is 1.14 times smaller than the tetrahedral species. Similarly in cage 3, the diffusion coefficients indicate that the minor species has a solvodynamic radius 1.16 times smaller (D = 7.60 × 10 -10 m 2 /s for the tetrahedral component and D = 8.85 × 10 -10 m 2 /s for the minor one). In both cases the secondary species is thus reduced in size by the same amount compared to the major cage, corresponding to the helicate impurities often observed in these systems. Finally, in cage 1, the diffusion coefficient was 1.05 × 10 -9 m 2 /s for the tetrahedral species, a lower value compared to cages 2 and 3. The discrepancy between the diffusion coefficients could be due to viscosity differences between the samples, or due to associated anions expanding the solvodynamic radii of the cationic assemblies to differing extents. While the MOC cores are analogous in structure, their solvodynamic radii cannot thus be compared directly using the Stokes-Einstein equation.