Two Novel 2D Lanthanide-organic Frameworks Based on Different Carboxylate-containing Mixed Ligands

Two novel lanthanide-organic polymers [Er-2(pdc)(2)(o-bdc)(H2O)(2)]center dot H2O (1, H(2)pdc = 2,6-pyridinedicarboxylic acid, o-H(2)bdc = 1,2-benzenedicarboxylic acid) and Er(Himdc)(m-bdc)(0.5)(H2O) (2, H(3)imdc = 4,5-imidazoledicarboxylic acid, m-H(2)bdc = 1,3-benzenedicarboxylic acid) have been synthesized and characterized by elemental analysis, IR, thermogravimetric analysis and X-ray single-crystal diffraction studies. 1 crystallizes in monoclinic, space group P2(1)/c, while 2 in the orthorhombic space group Pbcn. Both compounds 1 and 2 display two-dimensional network structures. For 1, the tetranuclear parallelogram {Er-4} cluster as a building block is further assembled into a wonderful 2D grid, and the layers are interconnected via hydrogen bonds and pi-pi stacking interactions to yield a 3D supramolecular architecture; for 2, its configuration is a rare double-decker structure. These two complexes represent good examples for using mix-carboxylate-containing ligands to construct diverse 2D lanthanide coordination polymers.