fig4

Figure 4. Formation of MOF membranes with perfect lattices. Zr₆O₄(OH)₄(-CO₂)₁₂ SBUs coordinate with diacid ligands to form a 12-connected Zr-MOF intergrown membrane on the surface of a porous substrate. This is the densest packing model of equal spheres in MOF crystals, analogous to a certain number of ligands touching 12 pairs of coordinative sites to weld a core SBU with the surrounding 12 SBUs. A sufficient driving force enabled by extra ligands-i.e., C (ligand) > C (metal cluster): C, concentration-can overcome the steric hindrance of nanoconfined spaces within intergrown MOF crystals to achieve complete coordination of a perfect MOF lattice in the membrane^[14]. Copyright 2023 Springer Nature. MOF: Metal-organic framework; SBUs: secondary building units.