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-μ-acetato-tetraaquabis(μ-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraterbium(III)] pentahydrate], {[Tb(CHO)(CHO)(CHNO)(HO)]·5HO}, (1), and poly[[tetra-μ-acetato-tetraaquabis(μ-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraeuropium(III)] tetrahydrate], {[Eu(CHO)(CHO)(CHNO)(HO)]·4HO}, (2), have been synthesized from biphenyl-3,3',5,5'-tetracarboxylic acid (Hbpt) and Ln(NO)·6HO (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/n space group. The crystal structures are constructed from bpt ligands (as linkers) and {Ln(μ-CHCOO)} 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).