A Robust Multifunctional Eu₆‑Cluster Based Framework for Gas Separation and Recognition of Small Molecules and Heavy Metal Ions

We report a multifunction lanthanide-based metal organic framework (Eu-SPFF) constructed by a hexanuclear Eu­(III) cluster and a tetracarboxylate ligand 4,4′,4″,4‴-(9,9′-spirobi­[fluorene]-2,2′,7,7′-tetrayl)­tetrakis­(2-fluorobenzoic acid) (H₄SPFF). The (4,12)-connected ftw topological three-dimensional structure contains octahedral and cubic cages with permanent porosity (BET: 1891.3 m² g^–1). Eu-SPFF not only exhibits high performance for the separation of light hydrocarbons but also shows highly selective recognition of 4-nitrophenol and Cu²⁺ ions.