Syntheses, Structures, Near-Infrared, and Visible Luminescence of Lanthanide-Organic Frameworks with Flexible Macrocyclic Polyamine Ligands

A series of lanthanide-based MOFs with flexible macrocyclic polyamine ligands, formulated as [Ln(H₂TETA)]NO₃·2H₂O (Ln = Nd (1), Eu (2), Tb (3), Dy (4), Y (5); H₄TETA = 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid) have been successfully synthesized and characterized. They possess the same 3D architectures and crystallize in triclinic space group P1̅. Their structures are built up from the paddle-wheel SBUs, which lead to 1D inorganic chains and further 3D framework with 13.26 × 10.94 Ų rhombic channels. The macrocyclic ligand displays special coordination pattern and protonation scheme. Complexes 1−3 exhibit strong fluorescent emissions in the visible and near-infrared region at room temperature. Formation of paddle-wheel structure plays crucial role in realizing efficient fluorescent emissions of complexes 1−3.