Lanthanide coordination frameworks: crystal structure, down- and up-conversion luminescence and white light emission†
Lanthanide–organic frameworks (LnOFs), [Sm(H2N-BDS)0.5(ox)(phen)] (1) and [Ln(H2N-BDS)(ox)0.5(phen)2] (Ln = Eu 2, Gd 3, Tb 4, Er 5, Yb 6; H2N-BDS = 2-amino-1,4-benzenedisulfonate, ox = oxalate, and phen = 1,10-phenanthroline) were obtained using hydrothermal synthesis. Structural analyses revealed that 1 is a three-dimensional (3D) pillared-layer structure constructed from [SmO6N2] polyhedra, and tetradentate H2N-BDS and tetradentate ox ligands, while complexes 2–6 are isostructural 2D frameworks, constructed from [LnO4N4] polyhedra, and bidentate H2N-BDS and tetradentate ox ligands. The LnOFs containing Sm(III), Eu(III) and Tb(III) ions exhibited the characteristic down-conversion luminescence of the corresponding Ln(III) ions. The Gd:Tb,Eu doped complex provided a white light emission. The Gd:Yb,Er doped complex exhibited up-conversion emissions at 410 nm (4H9/2 → 4I15/2, blue), 518–570 nm (4S3/2, 2H11/2 → 4I15/2, green), and 655 nm (4F9/2 → 4I15/2, red).