Synthesis, Crystal Structure, and Photoluminescence of a Series of Zinc(II) Coordination Polymers with 1,4-Di(1H-imidazol-4-yl)benzene and Varied Carboxylate Ligands

Six new coordination polymers [Zn-2(L)(OX)(2)] (1), [Zn-2(L)(1,2-BDC)(2)]center dot 2H(2)O (2), [Zn-2(L)(1,3-BDC)(2)(H2O)] (3), [Zn(L)(1,4-BDC)] (4), [Zn-2(L)(BPDA)(2)]center dot 2.68H(2)O (5), and [Zn-3(L)(2)(BTC)(2)(H2O)(2)]center dot 3H(2)O (6) were obtained by hydrothermal reactions of zinc(II) sulfate heptahydrate with rigid ditopic ligand 1,4-di(1H-imidazol-4-yl)benzene (L), sodium hydroxide, or tetra butylammonium hydroxide and the corresponding carboxylic acid, namely, oxalic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, or 1,3,5-benzenetricarboxylic acid, respectively. The complexes were characterized by single-crystal X-ray diffraction, IR, thermogravimetric, and elemental analyses. Complexes I and 2 are three-dimensional (3D) frameworks with infinite two-dimensional (2D) networks pillared by L ligands, and I possesses rare self-penetrating mab topology, while 2 shows ins topology. Complex 3 is a 2D bilayer network with infinite one-dimensional double Zn(II)-1,3-BDC2- chains linked by L ligands. Complexes 4-6 have multifold interpenetrating 3D structures: 4 has a 5-fold interpenetrating dia net, 5 has a 4-fold interpenetrating elongated primitive cubic alpha-Po structure, and 6 has a 3-fold interpenetrating framework. The results showed that the structural diversity of the complexes resulted from the different carboxylate ligands. Solid state properties such as photoluminescence and thermal stability of the complexes have been investigated.