Syntheses, Structures, and Luminescent Properties of Six New Zinc(II) Coordination Polymers Constructed by Flexible Tetracarboxylate and Various Pyridine Ligands

Under solvothermal conditions, six new Zn(II) coordination polymers, [(CH3)(2)NH2](2)[Zn(L)]center dot 2H(2)O (1), [Zn-2(L)(py)(2)] (2), [Zn-2(L)(bpe)(2)]center dot bpe center dot 6H(2)O (3), [Zn-2(L)(bpe)(DMA)(H2O)]center dot 5H(2)O (4), [Zn-2(L)(bpy)(0.5)(H2O)(2)]center dot 2.5H(2)O (5), and [Zn-2(L)(bpe)(H2O)]center dot 3H(2)O (6) [H4L = 5,5'-(p-xylylenediamino)-1,1',3,3'-(benzene-tetra-carboxylic acid), py = pyridine, bpy = 4,4'-dipyridine and bpe = 1,2-bis(4-pyridyl)ethane], have been synthesized by employing a flexible tetracarboxylic acid H4L and different auxiliary pyridine-based ligands. In 1-6, all L4- ligands are 4-connected nodes; however, the diverse configurations of the two terminal isophthalate units of L4- around the central -NHCH2PhCH2NH- spacer lead to various topological nets. 1 shows a three-dimensional (3D) 2-fold interpenetrated 4-connected dia network resulting from the vertical configuration of the two isophthalate units of L4-. 2 displays a 3D (4,4)-connected pts net in which the two isophthalate units of L4- adopt a parallel configuration. The two isophthalate units of L4- in 3 are also almost parallel, resulting in an intriguing 3D 2-fold interpenetrated network with the (4,4)-connected bbf net. 4 is a two-dimensional bilayer structure, extending into a 3D supramolecular framework through interlayer hydrogen-bonding interactions. 5 and 6 disclose similar 3D structural architectures, in which the two isophthalate units of L4- are almost vertical and exhibit tetrahedral topological nodes, inducing a rare (4,5)-connected xww net and an unprecedented (4,6)-connected network, respectively. The thermal stabilities and luminescent properties of 1-6 have also been studied in detail. The complexes exhibit intense solid-state fluorescent emissions at room temperature.