Syntheses, Structures and Fluorescence Properties of Four Zn/Cd(II) Coordination Polymers with 3-Nitrobenzene-1,2-dicarboxylate and Dipyridyl-typed Coligands

Four new coordination polymers [Zn(3-Nbdc)(bpa)] (n) (1), [Cd(3-Nbdc)(bpa)(H2O)] (n) (2), [Zn(3-Nbdc)(bpp)] (n) (3) and {[Zn(3-Nbdc)(bpe)]center dot 1.5H(2)O} (n) (4) (3-Nbdc = 3-nitrobenzene-1,2-dicarboxylate, bpa = 1,2-bi(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane and bpe = 1,2-bi(4-pyridyl)ethene), were synthesized hydrothermally and characterized structurally by single crystal X-ray diffractions, elemental analysis and infrared spectroscopy. Complexes 1 and 3 exhibit three-dimensional (3D) metal-organic frameworks with the (6(6)) dia topology and (6(5)center dot 8) cds topology, respectively, and both of them contain metal-carboxylate helix chains. Compounds 2 and 4 show 2D -> 3D interpenetrated networks with (4,4) grid layers and 2D layer, respectively, and both of them contain metal-carboxylate binuclear units. The thermal stabilities and fluorescence properties for complexes 1-4 are investigated. The blue-shift of the luminescent wavelength in 2 may be due to the absence of interligand pi center dot center dot center dot pi effects compared with that of other three compounds, but there exist the strong face-to-face pi center dot center dot center dot pi interactions in 1 and edge-to-face pi center dot center dot center dot pi interactions in 3 and 4, showing a certain degree of interchromophore coupling interaction.