A series of 3D isomorphous lanthanide coordination polymers based on flexible dicarboxylate ligand: Synthesis, structure, characterization, and properties

Seven lanthanide coordination polymers, namely, {[Ln(BDOA)1.5(H2O)]·H2O}n (Ln = Ce(I), Pr(II), Nd(III), Sm(IV), Eu(V), Gd(VI), and Tb(VII), H2BDOA = benzene-1,4-dioxydiacetic acid), have been synthesized through hydrothermal reactions of lanthanide nitrate with H2BDOA ligands and characterized by elemental analysis, infrared spectroscopy and single crystal X-ray diffraction. Findings indicate that I–VI are isomorphous and isostructural, containing the subunit of cavate 10-membered cages (Ln2O2(OCO)2), while VII possesses the subunit of cavate 14-membered cages (Tb2(OCO)4), based on which to assemble into three-dimensional porous architectures via BDOA2− ligands, hydrogen bonds and C–H⋯π interactions. I and III present antiferromagnetic behaviors and lanthanide contraction effect exists in I–VI. Luminescent studies suggest the typical intense emissions of Ln(III) ions occur in the visible region and therefore the coordination polymers display good selectivity towards some certain metal ions such as Ca2+ and Cd2+, showing promising potential as selective luminescent probes of these metal ions. In coordination polymer I, the adjacent two crystallographically equivalent Ce(III) ions are bridged by two oxygen atoms in μ2-η2 fashion and two carboxy groups in μ1-η1:η1 fashion to form a cavate 10-membered cage (Ce2O2(OCO)2) which serves as the subunit, based on which to generate a 3D porous architecture via BDOA2− ligands, hydrogen bonds and C–H⋯π interactions. [Display omitted] •Seven lanthanide coordination polymers are isomorphous.•The framework of Ln2O2(OCO)2 or Tb2(OCO)4 act as the subunits in the construction of I–VII.•I–VII are assembled into 3D porous architectures via coordinate covalent bonds, hydrogen bonds and C–H⋯π interactions.•Structure comparison of the coordination polymers suggests that lanthanide contraction effect exists.•I and III present antiferromagnetic behaviors and luminescent studies suggest I displays good selectivity towards Ca2+ and Cd2+.