Synthesis, crystal structure and photoluminescence of a three-dimensional zinc coordination compound with NBO-type topology

The assembly of metal-organic frameworks (MOFs) with metal ions and organic ligands is currently attracting considerable attention in crystal engineering and materials science due to their intriguing architectures and potential applications. A new three-dimensional MOF, namely poly[[diaqua(mu(8)-para-terphenyl-3,3',5,5'- tetracarboxylato)dizinc(II)] dimethylformamide disolvate monohydrate], {[Zn-2(C22H10O8)(H2O)(2)]center dot 2C(3)H(7)NO center dot H2O}(n), was synthesized by the self-assembly of Zn(NO3)(2)center dot 6H(2)O and para-terphenyl-3,3',5,5'-tetracarboxylic acid (H4TPTC) under solvothermal conditions. The compound was structurally characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each Zn-II ion is located in a square-pyramidal geometry and is coordinated by four carboxylate O atoms from four different TPTC4- ligands. Pairs of adjacent equivalent Zn-II ions are bridged by four carboxylate groups, forming [Zn-2(O2CR)(4)] (R = terphenyl) paddle-wheel units. One aqua ligand binds to each Zn-II centre along the paddle-wheel axis. Each [Zn-2(O2CR)(4)] paddle wheel is further linked to four terphenyl connectors to give a three-dimensional framework with NBO-type topology. The thermal stability and solid-state photoluminescence properties of the title compound have also been investigated.