Topological Diversities and Luminescent Properties of Lanthanide Metal-Organic Frameworks Based on a Tetracarboxylate Ligand

The reaction of 5,5'-(1,2-ethynediyl)bis(1,3-benzenedicarboxylic acid) (H4EBDC) and dinuclear lanthanide building blocks generates five new three-dimensional lanthanide metal organic frameworks (Ln-MOFs) with different topologies under mild conditions. Isomorphic compounds vertical bar C2H7N vertical bar[Ln(2)(EBDC)(NO3)(2)(C3H7NO)(4)] [Ln = Eu (1), Tb (2), or Er (3)] crystallize in monoclinic symmetry space group C2/c and adopt PtS topology. Under modified conditions, new phases vertical bar(NO3)(0.5)(H3O)(0.5)vertical bar[Yb-2(EBDC)(NO3)(2)(C3H7NO)(4)] (space group C2/c, compound 4) and vertical bar(H3O)(2)(C3H7No)(2.5)vertical bar [Eu-2(EBDC)(2)(C3H7NO)(H2O)] (space group P2(1)/c, compound 5) are obtained. In 4, both of the inorganic and organic building blocks can be simplified into a four-coordinate node, forming an Lvt topological network. For compound 5, the dinuclear Ln unit works as an 8-connected node and the organic ligand serves as a 4-connected node; these two kinds of nodes connect and then present an unprecedented (4,8)-connected topology. The aforementioned Ln-MOFs are all characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis, and their luminescent properties have been studied, showing emission characteristic of inorganic species at room temperature.