Synthesis, structure of 3D lanthanide (La(III), Pr(III)) nanoporous coordination polymers containing 1D channels as selective luminescent probes of Pb2+, Ca2+ and Cd2+ ions

Two kinds of 3D coordination polymers, namely, {[La2(PDA)3(H2O)4]·H2O}∞ (I) and {[Pr2(PDA)3(H2O)3]·H2O}∞ (II) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In complex I, La(III) ions are nine-coordinated and ten-coordinated and have N1O8 or N1O9 polyhedral units connecting to the PDA2− anions forming tricapped trigonal prism and double-capped cubic antiprism geometries, respectively. Two types of ring motifs as building blocks constructed by La8C2O10 (20-membered ring) and La4C2O6 (12-membered ring) are connected alternately into a highly ordered 2D sheet and further assembled into a nanoporous 3D coordination polymer with parallel channels. In complex II, Pr(III) ions are eight-coordinated and nine-coordinated and have N1O7 or N2O7 polyhedral units connecting to the PDA2− anions forming trigonal dodecahedron and tricapped trigonal prism configurations, respectively. The tetranuclear homometallic motifs formed by Pr4C4O8 unit (16-membered ring), acting as the building blocks, are constructed into a 3D coordination polymer. Luminescent emissions of the lanthanide-based MOF of complexes I and II have been measured in the solution of DMF at room temperature, which reveal that they presenting ion-selective characters toward certain metals, such as Pb2+, Ca2+ and Cu2+ or Cd2+ ions.