A series of two-dimensional lanthanide coordination polymers: synthesis, structures, magnetism and selective luminescence detection for heavy metal ions and toxic solvents.

A series of two-dimensional (2D) coordination polymers (CPs), namely poly[[bis(μ-acetato)diaqua(μ6-biphenyl-3,3',5,5'-tetracarboxylato)bis(N,N-dimethylacetamide)digadolinium(III)] N,N-dimethylacetamide monosolvate], {[Gd2(C16H6O8)(C2H3O2)2(C4H9NO)2(H2O)2]·C4H9NO}n (CP1), poly[[bis(μ-acetato)diaqua(μ6-biphenyl-3,3',5,5'-tetracarboxylato)bis(N,N-dimethylacetamide)didysprosium(III)] N,N-dimethylacetamide monosolvate], {[Dy2(C16H6O8)(C2H3O2)2(C4H9NO)2(H2O)2]·C4H9NO}n (CP2), poly[bis(μ-acetato)diaqua(μ6-biphenyl-3,3',5,5'-tetracarboxylato)bis(N,N-dimethylacetamide)dineodymium(III)], [Nd2(C16H6O8)(C2H3O2)2(C4H9NO)2(H2O)2]n (CP3), poly[bis(μ-acetato)diaqua(μ6-biphenyl-3,3',5,5'-tetracarboxylato)bis(N,N-dimethylacetamide)disamarium(III)], [Sm2(C16H6O8)(C2H3O2)2(C4H9NO)2(H2O)2]n (CP4), has been synthesized from rigid biphenyl-3,3',5,5'-tetracarboxylic acid under solvothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction and thermogravimetric analyses, and CP1-CP4 crystallize in the monoclinic space group P21/n. CP1-CP4 are isomorphous and feature similar 2D double layers, which are further extended via interlayer hydrogen-bonding interactions into a three-dimensional (3D) supramolecular structure. Hydrogen-bonding interactions between N,N-dimethylacetamide molecules and carboxylate O atoms strengthen the packing of the layers. The organic ligands interconnect with metal ions to generate 2D layered structures with a (4,4)-connected net having {44.62} topology. CP1 has been investigated for its magnetic properties and magnetic susceptibility measurements were carried out in the range 2.0-300 K. The results of the magnetic measurements show weak antiferromagnetic coupling between the GdIII ions in CP1. Moreover, the strong luminescence of CP2 and CP4 can be selectively quenched by the Fe3+ ion and toxic solvents (e.g. acetone).