Two Stable 3D Metal-Organic Frameworks Constructed by Nanoscale Cages via Sharing the Single-Layer Walls

In the past decade, the supramolecular assemblies of discrete cages as well as metal-organic frameworks (MOFs) with porous structures have developed rapidly due to their potential uses for gas separation and storage,1 ion-exchange,2 molecular and chiral recognition, and catalysis.3 For example, Yaghi et al. utilized secondary building units (SBUs) to serve as large vertices to construct MOFs with large channels for gas storage.1a-d MOFs with chiral recognition and catalysis properties have also been reported by Lin’s group.3g-i On the other hand, Stang3a-c and Fujita3d-f used planar rigid multipyridyl ligands and cis-protected square-planar metals to create a series of discrete nanoscale cages and macrocycles for molecular recognition and chiral catalysis. Discrete nanoscale cages can also be prepared by supramolecular assemblies of flexible or semirigid organic ligands with metal ions.4 So far, rare effort has been devoted to the combination of these two interesting field