Effect of pH/Auxiliary Ligand on the Structures of Coordination Compounds Based on a Novel Ligand 2,6-Bis(pyrazin-2-yl)pyridine-4-carboxylate

Four new coordination compounds, [Zn(bppc)(2)(H2O)(2)]center dot 3H(2)O (1), [Zn-2(bppc)(2)(mbdc)(H2O)4]center dot 7H(2)O (2), [Zn(bppc)2(H2O)(2)](n)center dot n(m-Hbdc)center dot n(H2O) (3), [Zn-2(bppc)(btc)(H2O)(3)](n)center dot 5nH(2)O (4) (Hbppc = 2,6-bis(pyrazin-2-yl) pyridine-4-carboxylate, H-2(m-bdc) = 1,3-benzenedicarboxylic acid, H(3)btc = 1,3,5-benzene-tricarboxylic acid), have been hydrothermally synthesized and structurally characterized. Compound 1 shows a mononuclear structure and 2 shows a dinuclear structure. Compound 3 is a one-dimensional chain structure, which is extended into a 3D supramolecular network by intermolecular hydrogen interactions. In 4, a 1D loop-like chain is connected by (btc) 3-anions to generate a 2D layer structure. The structure differences of 1 similar to 4 show that the pH and aromatic acid as auxiliary ligand have important influence on the final structures. (i)Additionally, the luminescent properties of 1 similar to 4 have been investigated with fluorescent spectra in the solid state, and 1 similar to 4 display a strong fluorescent emission at room temperature and have potential applications as fluorescent-emitting materials.