Jing-Jing Huang

Assembly of Zn/Cd coordination polymers containing helixes or polycatenane structures tuned by the tri-pyridyl–bis-amide ligands with different spacer: syntheses, structures, photoluminescent and photocatalytic properties

Four new d10 metal–organic coordination polymers tuned by the “V”-shaped tri-pyridyl–bis-amide ligands with different spacers, namely, [Zn(L1)(BDC)]·H2O (1), [Cd(L1)(BDC)]·H2O (2), [Zn(L2)(BDC)] (3) and [Cd(L2)(BDC)] (4) (L1 = N,N′-bis(pyridine-3-yl)pyridine-2,6-dicarboxamide, L2 = N,N′-bis(pyridine-3-yl)pyridine-3,5-dicarboxamide, H2BDC = 1,4-benzenedicarboxylic acid) have been synthesized under hydrothermal conditions. In complexes 1 and 2, the metal ions are linked by L1 to form left- and right-helical Zn/Cd–L1 chains, which are further extended into two-dimensional (2D) wave-like layers by BDC anions. In 3, two L2 ligands link two ZnII ions forming the Zn2(L2)2 loops, which are connected by BDC anions to form a (2·65) topological 2D network. In addition, the large Zn2(L2)2 loops are threaded by the BDC rods from above and below 2D layers so as to form 2D → 3D polyrotaxane and polycatenane structures. In 4, the CdII ions are linked by L2 ligands to generate 1D double chain ribbons with Cd2(L2)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 properties

The hydrothermal reaction of CoCl2 with N,N′-bis(pyridine-3-yl)pyridine-3,5-dicarboxamide (L) and 1,3,5-benzenetricarboxylic acid (H3BTC) mixed ligands affords two novel polynuclear cobalt cluster-based metal–organic frameworks (MOFs), [Co3(L)2(BTC)2(H2O)2]·6H2O (1) and {[Co2(L)(BTC)(OH)]·2.5H2O}2 (2). Single crystal X-ray diffraction analysis reveals that the CoII ions in complex 1 are connected by BTC anions with a four-coordinated mode to form a two dimensional (2D) undulating layer based on dinuclear [Co2(COO)4] units, which is extended into a 3D (3, 4, 4, 5)-connected MOF by the L ligand with μ3-bridging coordination mode. In complex 2, the BTC ligand displays a six-coordinated mode to connect CoII ions into a 2D corrugated layer derived from tetranuclear [Co4(μ3-OH)2(COO)6] motifs, and the layers are further extended into a 3D (3, 8)-connected tfz-d MOF via μ2-bridging L ligands. The title complexes exhibit a (42·63·85)2(42·63·8)2(6·82)2(62·84) topology for 1 and a (43)2(46·618·84) topology for 2. The pH value, as well as the various coordination modes of the tri-pyridyl-bis-amide L and BTC ligands, play a crucial role in the construction of the diverse topological structures of 1 and 2. Complex 1 exhibits excellent photocatalytic activity for dye degradation under UV light. In addition, the electrochemical behaviour and magnetic and fluorescent properties of the two complexes have also been investigated.

Five bis(imidazole)-based Coordination Polymers Tuned by Central Metal Ions and S-containing Dicarboxylates: Syntheses, Structures, and Properties

Five new coordination polymers, namely [Zn(2-CMSN)(biim-4)] (1), [Co2(2-CMSN)2(biim-4)(H2O)4] (2), [Ni(2-CMSN)(biim-4)0.5(H2O)2] (3), [Cd(2-CMSN)(biim-4)0.5(H2O)2] (4), and [Cd(ADTZ)(biim-4)1.5]·5H2O (5), (2-H2CMSN = 2-carboxymethylsulfanyl nicotinic acid, H2ADTZ = 2,5-(S-acetic acid) dimercapto-1,3,4-thiadiazole, biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole)) have been synthesised under hydrothermal conditions and structurally characterised by single-crystal X-ray diffraction analysis, infrared spectroscopy, elemental analysis, thermogravimetric analysis, and powder X-ray diffraction. Complex 1 shows a 2D undulated sheet, which is constructed from 1D meso-helical [Zn-(biim-4)]n chains and linear [Zn-(2-CMSN)]n chains. Complexes 2–4 exhibit a similar 2D (4,4) grid network constructed from zigzag [M-(2-CMSN)]n chains and linear [M-(biim-4)]n chains (M = CoII, NiII and CdII), which possesses a ‘4+2’ type six-membered ring. Complex 5 displays a 3D architecture derived from 2D Cd-(biim-4) layers and double ADTZ linkers with diamond-type 66 topology. The effects of the central metals and S-containing dicarboxylates on the structures of the title coordination polymers have been discussed. The luminescent properties of complexes 1, 4, and 5 have been studied. Complex 5 exhibits photocatalytic activity for dye degradation under ultraviolet light and good stability towards photocatalysis.