Search

Abstract: Two novel Zn(II) coordination polymers, [Zn5(pytpy)8(fum)4(H2O)4(OH)2] n · n(CH3OH)·2n(H2O) (1) and [Zn3(pytpy)4 (btc)2] n ·2n(H2O) (2) (pytpy=4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H2fum=fumaric acid, H3btc=1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum2− anions. Complex 2 is a 3D network structure, μ2-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350°C. [Copyright &y& Elsevier]

Abstract: Using the principle of crystal engineering, six metal-organic coordination polymers, [Cd(bdc)(3-pytpy)] n ·2nH2O (1), [Cd(bdc)0.5(3-pytpy)] n · n(ClO4) (2), Cd(ndc)0.5(3-pytpy)] n · n(ClO4) (3), [Zn(ndc)(3-pytpy)] n (4), [Cd(bqdc)(3-pytpy)] n (5), and [Zn(pam)(3-pytpy)] n ·2nH2O (6) (H2bdc=benzene-1,4-dicarboxylic acid, H2ndc=naphthalene-2,6-dicarboxylic acid, H2bqdc=2,2′-biquinoline-4,4′-dicarboxylic acid, H2pam=pamoic acid), were synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. Compounds 1–6 crystallize in the presence of organic-acid linkers as well as multi-functional N-donor ligand 4′-(3-pyridyl)-2,2′:6′,2′′-terpyridine (3-pytpy). In complexes 1, 4, 5, and 6, the dicarboxylate as bridging ligand connects metal atoms to form the main body of 1D zigzag chains for 1 and 4, nearly linear chain for 5 and helical chain for 6, while 3-pytpy as tridentate chelating ligand is just like lateral arm grafting on both sides of these chains. In complexes 2 and 3, both the dicarboxylate and 3-pytpy as bridging ligands connect metal atoms into 2D polymeric structure for 2 and 1D chain of alternating loops and rods for 3. The weak interactions such as hydrogen bonding and π···π stacking were investigated on the formation of superamolecular structures and the influence of organic acid on the formation of the final structures was discussed. In addition, the photoluminescent properties of 1–6 were also determined. [Copyright &y& Elsevier]