In Situ Cation‐Switched Organometallic Cage Reconfiguration Enables Highly Selective Li+ Recognition and Extraction

Abstract Biomacromolecular selectivity paradigms, epitomized by the “induced‐fit” concept, motivate adaptive supramolecular designs; however, cationic guest‐directed morphological responses in metal‐coordinated hosts remain inadequately developed. We reveal a dynamic Ag I ‐ N ‐heterocyclic carbene (NHC) cage that experiences alkali ion‐induced structural metamorphosis triggered by Lewis acid‒base interactions. X‐ray crystallographic analysis and independent gradient model (IGM) evidence confirm that these interaction templates have highly ordered architectures exceeding 340 non‐H atoms. Competitive affinity assessments exhibit unprecedented Li + discrimination against Na + /K + (Li + > Na + > K + ), outperforming commercial benchmark chelators (e.g., crown ethers and cryptands). Capitalizing on this trait, we fabricated a supramolecular extractant for targeted Li + isolation from both an equimolar Li + /Na + /K + brine and a high‐Mg 2+ brine ( c (Mg 2+ )/ c (Li + ) ≈ 2000/1). Subsequent carbonate‐induced reconfiguration reverts the initial metallocage, permitting cyclic utilization. This study deciphers cation‐modulated plasticity in coordination architectures and offers a recyclable bioinspired platform for precision ion recognition and extraction.