Guiding the De Novo Synthesis of Open Metal Frameworks Through Low‐Symmetry Bent Linker for Hydrogen Isotope Separation

Open metal sites (OMS) serve as crucial active sites in numerous applications, including hydrogen isotope separation, highlighting the importance of developing targeted synthesis strategies for OMS‐containing frameworks. Unlike defect‐engineered approaches that generate disordered OMS, synthesizing frameworks with an ordered distribution of OMS remains highly challenging yet is essential for efficient separation. Guided by the topological simplification process—which abstracts connectivity while overlooking coordination geometry—this study introduces a strategy to construct metal‐organic frameworks (MOFs) with ordered OMS by reducing linker symmetry. By employing bent linkers with lower axial symmetry, rather than linear linkers of equivalent topological connectivity, OMF‐2 (OMF = Open‐Metal Framework) was synthesized, a pcu 8‐connected framework featuring four OMS per cluster, thereby validating the approach. Remarkably, OMF‐2 demonstrates exceptional hydrogen isotope separation performance, with an ideal adsorbed solution theory (IAST) selectivity of 7.7, a cryogenically programmed desorption (CPD) selectivity of 6.6, and a breakthrough test selectivity of 2.3 for D 2 /H 2 . The ordered arrangement of OMS within the pore windows enhances both chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS) effects. This work establishes a new pathway for the targeted synthesis of MOFs with both ordered OMS structural features and strong application potential.