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Architecture of zero-, one-, two- and three-dimensional structures based on metal ions and pyrazine-2,6-dicarboxylic acid

Publication Date
DOI: 10.1016/j.poly.2007.11.012
  • Pyrazine-2
  • 6-Dicarboxylic Acid
  • Metal Ions
  • Structural Versatility
  • Coordination Modes


Abstract Six new complexes: [Ln 2(pzda) 3(H 2O) 2] · 2.5H 2O (Ln = Nd, ( 1); Eu, ( 2)), [Co(pzda) (bpe)] · 0.125(bpe) · 1.75H 2O ( 3), [Mn(pzda)(H 2O) 1.5] ( 4), [Co 2(pzda) 2(bpe)(H 2O) 4] · 0.5(CH 3OH) · H 2O ( 5) and [Co(pzda)(2,2′-bpy)(H 2O)] · 0.5H 2O ( 6) (H 2pzda = pyrazine-2,6-dicarboxylic acid, bpe = 1,2-bis(4-pyridyl)ethane, 2,2′-bpy = 2,2′-bipyridine) were obtained from metal salts and H 2pzda 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 1 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 μ 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.

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