Charge-, Size-, and Symmetry-Matched Pore Partitioning in Metal-Organic Frameworks.

Abstract

The pore-space-partition (PSP) strategy, which subdivides large pores into smaller segments, has proven highly effective in flexible acs-type frameworks. However, extending this approach to rigid structures has remained a formidable challenge due to the strict size and symmetry constraints required for partitioning ligands. In this study, we successfully overcome these limitations and, for the first time, apply the PSP strategy to rigid acs frameworks. This breakthrough relies on the precise geometric and size compatibility between the parent framework and specially designed partitioning ligands. A series of metal-organic frameworks (MOFs) based on four ligand pairs and four metal combinations are synthesized. Notably, MOFs incorporating partitioning ligands with a hexaazaphenalene core exhibited exceptional benzene adsorption properties. Among these, the neutral NNM-750-Fe, featuring ideal charge balance between the metal trimer (+1) and the partitioning ligand (-1), demonstrated significantly enhanced benzene uptake at low pressure compared to non-partitioned and charged-partitioned analogues. This work not only expands the boundaries of the PSP strategy to rigid frameworks but also opens new avenues for the rational design of high-performance porous materials for advanced separation and adsorption applications.