A Series of 3D Lanthanide complexes containing (La(III), Sm(III) and Gd(III)) metal-organic frameworks: Synthesis, structure, characterization and their luminescent properties

Abstract

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, {[Ln2(PDA)3(H2O)3]0.25H 2O} (Ln = La(1), Sm(2), and Gd(3)) (PDA2- = pyridine-2,6- dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the N1O7 and N2O7 donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic Ln2C2O2 unit (16- membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as Mg2+, Cd2+ and Pb2+ ions.