Hydrothermal Synthesis, Crystal Structure, and Luminescent Properties of Two Zinc(II) and Cadmium(II) 3D Metal-Organic Frameworks

Two zinc(II) and cadmium(II) metal-organic frameworks with mixed ligands, {[Zn2(biim-4)2(TDC)2]center dot 2.5H2O}n (1) and {[Cd2(biim-4)2(TDC)2 center dot 2H2O]}n (2) [biim-4 = 1,1-(1,4-butanediyl)bis(imidazole); H2TDC = thiophene-2,5-dicarboxylic acid], were hydrothermally synthesized. Both of them are characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction. In 1, the four-connected ZnII nodes are connected by four linear ligands extending into a 3D network, which further integrates a fivefold interpenetrating diamond 3D topological network and the free water molecules distribute in void space, whereas in 2, the CdII ions are in a distorted octahedral arrangement linked by TDC2 and biim-4 ligands to construct a 3D framework. In topology analysis, C11 and C14 are simplified as 3-connected nodes and the 3D framework displays a (3,5)-connected net. Furthermore, the thermal and photoluminescent properties of 1 and 2 were also studied.