Syntheses, structures, magnetic and photoluminescence properties of metal-organic frameworks based on aromatic polycarboxylate acids

Six new coordination compounds, namely [Co(H(2)bptc)](n) (1), [Mn(H(2)bptc)](n) (2), [Cd-2(bptc)(phen)(2)(H2O)(2)](n) (3), [Eu-2(cpa)(3)(DMF)(2)](n) (4), [Nd-2(cpa)(3)(DMF)(2)](n) (5) and [Pr-2(cpa)(3)(DMF)(2)](n) (6) (bptc(4-) = biphenyl-2,2',4,4'-tetracarboxylate anion, phen 1,10-phenanthroline, cpa(2-) = 4-chloroisophthalic acid anion) were synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Co and Mn compounds are isostructural, and possess a three-dimensional 5, 5-connected network. In Cd compound, multicarboxylate ligand H(4)bptc link Cd centers to generate a two-dimensional 4, 4-c net structure with phen acting as terminal ligand. Eu, Nd, and Pr compounds have similar structures, and cpa(2-) ligands link lanthanide cations to generate a two-dimensional sheet structure. Magnetic susceptibility measurements indicate that the Co compound has a dominating ferromagnetic coupling between Co(II) ions, and Mn compound exhibits antiferromagnetic coupling between Mn(II) ions. Furthermore, their luminescent properties are also determined in the solid state at room temperature.