Efficient screening for enhanced Xe/Kr separation via fixed-ligand, variable-metal strategy in metal-organic...

The separation of xenon (Xe) and krypton (Kr), being an energy-intensive process, has attracted considerable research interest in developing alternative separation methods and materials over the past two decades. Considerable progress has been achieved in discovering sorbent materials with high Xe/Kr selectivity. Due to their tunable pore geometries and interaction strengths, metal-organic frameworks (MOFs) have gained consensus as promising alternatives. For this goal, computational screening methods have been widely adopted to accelerate the discovery of high-performing candidates. However, the computational cost of brute-force screening involving adsorption simulations for millions of structures is prohibitive. Therefore, a practical approach is to partition large-scale screening into manageable subsets focusing on materials with shared chemical features. To conserve computational resources, applying reasonable filters on pore-related geometric features demonstrating significant variation is advisable. Based on these considations, we present a ligand-focused screening strategy employing preliminary geometric filters, including a pore-limiting diameter (PLD) ranging from 3.3 to 8.2 Å and a largest cavity diameter (LCD)/PLD ratio between 1 and 2, together with the restriction to single-ligand-assembled MOFs to facilitate structure-property interpretation. The procedure is exemplified using the ligand 1,1,2,2-tetra(4-carboxyphenyl)ethylene (H₄TCPE), and experimentally validated the in silico workflow through laboratory synthesis and adsorption measurements. The optimal cerium-based framework exhibits a 143% improvement in the adsorbent performance indicator (API), which comprehensively considers selectivity, uptake, and enthalpy, compared to the prior Ca-based analog. Rather than targeting high-throughput discovery, this study demonstrates an efficient and chemically interpretable screening approach for a structurally coherent MOF subfamily. The resulting materials are further contextualized against representative benchmark adsorbents, highlighting their competitive performance and application-relevant advantages.