Figure 1.

A and B self‐assembled with 2‐formylpyridine and Co^II to form 1 and 2, respectively. Three‐dimensional views are constructed from the X‐ray crystal structures of 1 and ClO₄ ⁻⊂2 (Co^II: orange, L^A: blue, L^B: red; orange lines indicate the closest metal–metal separations, to illustrate geometry). The insert gives the list of guests encapsulated by 2 but not 1 along with their volumes (ų).