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The design and synthesis of functional coordination polymers is motivated not only by their structural beauty but also by their potential applications. ZnII and CdII coordination polymers are promising candidates for producing photoactive materials because these d10 metal ions not only possess a variety of coordination numbers and geometries, but also exhibit luminescence properties when bound to functional ligands. It is difficult to predict the final structure of such polymers because the assembly process is influenced by many subtle factors. Bis(imidazol-1-yl)-substituted alkane/benzene molecules are good bridging ligands because their flexibility allows them to bend and rotate when they coordinate to metal centres. Two new ZnII and CdII coordination polymers based on mixed ligands, namely, poly[[μ2-1,4-bis(imidazol-1-ylmethyl)benzene-κ2 N3: N3′]bis(μ3-2,2-dimethylbutanoato-κ3 O1: O4: O4′)dizinc(II)], [Zn2(C6H8O4)2(C14H14N4)] n, and poly[[μ2-1,4-bis(imidazol-1-ylmethyl)benzene-κ2 N3: N3′]bis(μ3-2,2-dimethylbutanoato-κ5 O1, O1′: O4, O4′: O4)dicadmium(II)], [Cd2(C6H8O4)2(C14H14N4)] n, have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric analysis. Both complexes crystallize in the monoclinic space group C2/ c with similar unit-cell parameters and feature two-dimensional structures formed by the interconnection of S-shaped Zn(Cd)-2,2-dimethylsuccinate chains with 1,4-bis(imidazol-1-ylmethyl)benzene bridges. However, the CdII and ZnII centres have different coordination numbers and the 2,2-dimethylsuccinate ligands display different coordination modes. Both complexes exhibit a blue photoluminescence in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

The design and preparation of crystalline polymeric materials has attracted increasing attention due to their diverse applications as functional materials in gas storage, separation, catalysis, sensing and photoluminescence. The judicious selection of organic linkers is critical for varying the coordination behaviour of the metal ions and determining the overall characteristics of the networks. A new adenine-based ZnII coordination polymer, [Zn(C6H2O4S)(C5H5N5)] n or [Zn(tdc)(9H-ade)] (H2tdc is thiophene-2,5-dicarboxylic acid and ade is adenine), has been prepared hydrothermally and the crystal structure exhibits in its packing two-dimensional (4,4) grid sheets parallel to the ab plane, featuring two distinct square cavities delimited by the two types of ligands and the ZnII ions with the dimensions 6.6 × 6.6 and 10.2 × 10.2 Å (based on the Zn...Zn distance). The title complex shows enhanced photoluminescence at 378 nm compared to the free ligands, suggesting that the coordination of H2tdc or adenine to the metal centre effectively increases the rigidity of the ligands and reduces the energy loss by radiative decay of intraligand excited states. [ABSTRACT FROM AUTHOR]

The title compound, (C6H9N2S)[ZnCl3{SC(NH2)2}], exists as a zincate where the zinc(II) centre is coordinated by three chloride ligands and a thiourea ligand to form the anion. The organic cation adopts the protonated 4,6-dimethyl-2-sulfanylidenepyrimidin-1-ium ( L) form of 4,6-dimethylpyrimidine-2(1 H)-thione. Two short N-H...Cl hydrogen bonds involving the pyrimidine H atoms and the [ZnCl3 L]− anion form a crystallographically centrosymmetric dimeric unit consisting of two anions and two cations. The packing structure is completed by longer-range hydrogen bonds donated by the thiourea NH2 groups to chloride ligand hydrogen-bond acceptors. [ABSTRACT FROM AUTHOR]