A Noninterpenetrated Molecular Ladder with Hydrophobic Cavities

Not interpenetrated, but filled with solvent molecules, the large cavities of the polymer Co(NO3)2(4,4′-bpy)1.5n form different structures depending on the solvent system from which it crystallizes. One of the two possible structures (section of structure shown on the right) exhibits hydrophobic cavities about 11 × 11 Å in size. The solvent molecules can be readily removed, but the process has not yet been proven reversible.