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

Abstract

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)]·1.5H2O} 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 (66) dia topology and (65·8) 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 π···π effects compared with that of other three compounds, but there exist the strong face-to-face π···π interactions in 1 and edge-to-face π···π interactions in 3 and 4, showing a certain degree of interchromophore coupling interaction.