Four new d 10 metal-organic coordination polymers tuned by the ''V''-shaped tri-pyridyl-bis-amide ligands with different spacers, namely, [Zn(L 1 )(BDC)]? 3) and [Cd(L 2 )(BDC)] (4) (L 1 = N,N9-bis(pyridine-3-yl)pyridine-2,6-dicarboxamide, L 2 = N,N9-bis(pyridine-3-yl)pyridine-3,5-dicarboxamide, H 2 BDC = 1,4-benzenedicarboxylic acid) have been synthesized under hydrothermal conditions. In complexes 1 and 2, the metal ions are linked by L 1 to form left-and right-helical Zn/ Cd-L 1 chains, which are further extended into two-dimensional (2D) wave-like layers by BDC anions. In 3, two L 2 ligands link two Zn II ions forming the Zn 2 (L 2 ) 2 loops, which are connected by BDC anions to form a (2?6 5 ) topological 2D network. In addition, the large Zn 2 (L 2 ) 2 loops are threaded by the BDC rods from above and below 2D layers so as to form 2D A 3D polyrotaxane and polycatenane structures. In 4, the Cd II ions are linked by L 2 ligands to generate 1D double chain ribbons with Cd 2 (L 2 ) 2 loops, which are further connected by the BDC linkers to form a 3D framework. Two identical 3D frameworks interpenetrate each other in a twofold mode, giving rise to a polyrotaxane and polycatenane array, which is relative limited.The diverse structures of complexes 1-4 demonstrate that the tri-pyridyl-bis-amide ligands and the central metals have significant effect on the final structures. The thermal stability and fluorescent properties of complexes 1-4 have been investigated. In addition, the title complexes exhibit photocatalytic activity for dye methylene blue degradation under UV light.

pH-dependent two novel 3D polynuclear cobalt(II) cluster-based metal-organic frameworks constructed from a tri-pyridyl-bis-amide and a polycarboxylate: assembly, structures and properties3

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Two Co(II) coordination polymers, [CoL(npa)]·2H 2 O (1) and [CoL(Hnpa) 2 ] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H 2 npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ 2 -bridging mode and connecting two Co 2+ cations to generate a 26-membered Co 2 L 2 loop. The npa 2− link adjacent Co 2 L 2 loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa − adopt a μ 1 -η 0 : η 1 coordination to connect adjacent Co 2+ cations into a 2-D polymeric layer. The μ 2 -bridging L ligands connect adjacent 2-D [Co(Hnpa)] n polymeric layers into a 3-D NaCl-like framework. The Co 2+ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated.