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(H<sub>2</sub>TETA)]NO<sub>3</sub>·2H<sub>2</sub>O (Ln = Nd (<b>1</b>), Eu (<b>2</b>), Tb (<b>3</b>), Dy (<b>4</b>), Y (<b>5</b>); H<sub>4</sub>TETA = 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 <i>P</i>1̅. 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 Å<sup>2</sup> rhombic channels. The macrocyclic ligand displays special coordination pattern and protonation scheme. Complexes <b>1</b>−<b>3</b> 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 <b>1</b>−<b>3</b>.