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

Abstract

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 |C2H7N|[Ln2(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 |(NO3)0.5(H3O)0.5|[Yb2(EBDC)(NO3)2(C3H7NO)4] (space group C2/c, compound 4) and |(H3O)2(C3H7NO)2.5|[Eu2(EBDC)2(C3H7NO)(H2O)] (space group P21/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.