Increasing the Stability of Metal-Organic Frameworks
Figure 5
The Zr6O8 unit of PCN-521, which is similar to that of UiO-66 except that it is 8-connected instead of 12 connected, having a “cubic” symmetry that is compatible with the tetrahedral ligands used. The equatorial Zr atoms are coordinated by hydroxyl groups on the periphery of the unit [24].
