Two novel lanthanide(III) organic frameworks based on a biphenyltetracarboxylate ligand: synthesis, structure and magnetic and luminescence properties

Two new two-dimensional lanthanide coordination polymers, namely poly[[tetra-mu(2)-acetato-tetraaquabis(mu(4)-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis-(dimethylacetamide)tetraterbium(III)] pentahydrate], {[Tb-4(C16H6O8)(2)(C2H3O2)(4)-(C4H9NO)(4)(H2O)(4)]center dot 5H(2)O}(n), (1), and poly[[tetra-mu(2)-acetato-tetraaquabis(mu(5)-biphenyl-3,3',5,5'-tetracarboxylato) tetrakis(dimethylacetamide)tetraeuropium(III)] tetrahydrate], {[Eu-4(C16H6O8)(2)(C2H3O2)(4)(C4H9NO)(4)(H2O)(4)]center dot 4H(2)O}(n), (2), have been synthesized from biphenyl-3,3',5,5'-tetracarboxylic acid (H(4)bpt) and Ln(NO3)(3)center dot 6H(2)O (Ln = Tb and Eu) under solvothermal conditions. Single-crystal X-ray structure analysis shows that the two compounds are isostructural and crystallize in the monoclinic P2(1)/n space group. The crystal structures are constructed from bpt(4-) ligands (as linkers) and {Ln(2)(mu(2)-CH3COO)(2)} building units (as nodes), which topological analysis shows to be a (4,6)-connected network with sql topology. Compounds (1) and (2) have been characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and fluorescence analysis in the solid state. In addition, a magnetic investigation shows the presence of antiferromagnetic interactions in compound (1).