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摘要
Six new complexes: [Ln(2)(pzda)(3)(H2O)(2)]center dot 2.5H(2)O (Ln=Nd, (1); Eu, (2)), [Co(pzda) (bpe)]-0.125(bpe)-1.75H(2)O (3), [Mn(pzda)(H2O)1.5] (4), [CO2(pzda)(2)(bpe)(H2O)(4)] center dot 0.5(CH3OH) center dot H2O (5) and [Co(pzda)(2,2'-bpy)(H2O)] center dot 0.5H(2)O (6) (H(2)Pzda = pyrazine-2,6-dicarboxylic acid, bpe = 1,2-bis(4-pyridyl)ethane, 2,2'-bpy = 2,2'-bipyridine) were obtained from metal salts and H2Pzda under hydro(solvo)thermal conditions. The single crystal X-ray structural analysis reveals that the title complexes have different structures, ranging from zero- to three- dimensions, which are mainly due to the different metal ions, and especially the coordination modes of the pzda ligands. Complexes I and 2 have 3D metal-organic frameworks containing a 1D tri-strand array, in which the pzda ligand adopts a pentadentate mode to link lanthanide ions. Complex 3 has a 2D metal-organic framework, in which the pzda ligand acts in a tetradentate mode to connect Co(II) ions into 1D chains, which are further connected by bpe spacers into a 2D framework. While in 4, both of the two carboxylate groups of the pzda ligand adopt mu(2)-O bridging modes to link Mn(II) ions into a 1D coordination polymer, which is further assembled into a 2D supramolecular network containing double-stranded hydrogen-bonded helical chains. In both 5 and 6, the pzda ligand binds metal ions as a tridentate ligand (ONO mode) to form zero dimensional structures. Complex 5 is a binuclear molecule, while 6 is a mononuclear complex, which can be attributed to the bridging ligand bpe for 5 and the terminal auxiliary ligand 2,2'-bpy for 6.
