Structural diversity and photocatalytic properties of Cd(II) coordination polymers constructed by a flexible V-shaped bipyridyl benzene ligand and dicarboxylate derivatives.

Hydrothermal reactions of Cd(OAc)2·2H2O with a flexible V-shaped bipyridyl benzene ligand and five benzenedicarboxylic acid derivatives gave rise to five new coordination polymers i.e., [Cd(1,4-BDC)(bpmb)(H2O)]n (1), {[Cd(1,3-BDC)(bpmb)]·0.125H2O}n (2), [Cd2(5-Me-1,3-BDC)2(bpmb)2]n (3), [Cd(5-NO2-1,3-BDC)(bpmb)(H2O)]n (4) and [Cd(5-OH-1,3-BDC)(bpmb)(H2O)]n (5) (bpmb = 1,3-bis(pyridine-3-ylmethoxy)benzene, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, 5-Me-1,3-H2BDC = 5-methyl-1,3-benzenedicarboxylic acid, 5-NO2-1,3-H2BDC = 5-nitro-1,3-benzenedicarboxylic acid, 5-OH-1,3-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 is a two-fold interpenetrating network showing the coexistence of polyrotaxane and polycatenane characters. Compounds 2 and 3 exhibit similar 2D (3,5)-connected (4(2)·6(7)·8)(4(2)·6) nets in which the bpmb ligands work as lockers in interlocking 1D [Cd(1,3-BDC/5-Me-1,3-BDC)]n chains. Compound 4 shows a 2D 4-connected (6(6)) sandwich-like structure with differently oriented [Cd(5-NO2-1,3-BDC)]n chains. Compound 5 is a 3D supramolecular pcu net based on a 1D ladder-shaped chain. These results suggest that the substituted positions of carboxylate groups and changes in substituted R groups in the 5-position of BDC ligands have significant effect on the final structures. These compounds exhibited relatively good photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV irradiation. Moreover, solid-state photoluminescence properties of 1-5 were also investigated.

A helical zinc(II) coordination polymer assembled from 1,3-bis[(pyridin-3-yl)methoxy]benzene and benzene-1,4-dicarboxylic acid.

In catena-poly[[aqua[1,3-bis(pyridine-3-ylmethoxy)benzene-κN]zinc(II)]-µ2-benzene-1,4-dicarboxylato-κ(2)O(1):O(4)], [Zn(C8H4O4)(C18H16N2O2)(H2O)]n, each Zn(II) centre is tetrahedrally coordinated by two O atoms of bridging carboxylate groups from two benzene-1,4-dicarboxylate anions (denoted L(2-)), one O atom from a water molecule and one N atom from a 1,3-bis[(pyridin-3-yl)methoxy]benzene ligand (denoted bpmb). (Aqua)O-H···N hydrogen-bonding interactions induce the formation of one-dimensional helical [Zn(L)(bpmb)(H2O)]n chains which are interlinked through (aqua)O-H···O hydrogen-bonding interactions, producing two-dimensional corrugated sheets.

Three coordination polymers constructed from various polynuclear clusters spaced by 2,2'-azodibenzoic acid: syntheses and fluorescent properties.

Solvothermal reactions of M(OAc)2·2H2O (M = Zn, Cd, Pb) with 2,2'-azodibenzoic acid (H2L) in MeOH-H2O (MeOH = methanol) at 120 °C gave rise to three coordination polymers, [Zn12(µ4-O)3L9]n (1), [CdL(H2O)]n (2) and [Pb3(µ4-O)L2]n (3). Compounds 1-3 are characterized by elemental analysis, IR, powder X-ray diffraction and single-crystal X-ray diffraction. Compound 1 has two similar tetranuclear [Zn4(µ4-O)(µ2-CO2)6] units as nodes and displays an intriguing three-dimensional (3D) 6-connected network with a 4(12)6(3) topology. Compound 2 exhibits a 3D framework constructed by linking infinite helical Cd-carboxylate chains through L ligands. Compound 3 holds a 3D structure in which each hexanuclear [Pb6(µ4-O)2(CO2)4] unit works as a six-connecting node to connect its equivalent ones via sharing L ligands. In addition, the fluorescent properties and thermal stabilities of 1-3 were also investigated.

A sodalite-type porous metal-organic framework with polyoxometalate templates: adsorption and decomposition of dimethyl methylphosphonate.

A sodalite-type porous metal-organic framework with polyoxometalate templates, H(3)[(Cu(4)Cl)(3)(BTC)(8)](2)[PW(12)O(40)]·(C(4)H(12)N)(6)·3H(2)O (NENU-11; BTC = 1,3,5-benzenetricarboxylate), was obtained by a hydrothermal reaction. As a reasonable candidate for eliminating nerve gas, NENU-11 displays good adsorption behavior for dimethyl methylphosphonate (15.5 molecules per formula unit). In virtue of the catalytic activity of polyoxometalate guests, this nerve gas mimic could be facilely decomposed by a hydrolysis reaction.

Reactivity of polyoxoniobates in acidic solution: controllable assembly and disassembly based on niobium-substituted germanotungstates.

The reactivity of polyoxoniobates has been studied in acidic solution by grafting niobium onto trivacant Keggin-type germanotungstates. Four niobium-containing compounds were obtained in the course of this study. Cs(6.5)K(0.5)[GeW(9)(NbO(2))(3)O(37)]·6H(2)O (Cs(6.5)K(0.5)-1) synthesized by the reaction of K(7)H[Nb(6)O(19)] and A-α-Na(10)[GeW(9)0(34)] in H(2)O(2) solution is a tris(peroxoniobium)-substituted A-α-GeW(9) derivative. Cs(6.5)K(0.5)[GeW(9)Nb(3)O(40)]·10H(2)O (Cs(6.5)K(0.5)-2) is a peroxo-free compound obtained by eliminating the peroxo groups in 1. Monomers 1 and 2 as precursors can each afford two nanoscale POMs, dimer Cs(5)[H(15)Ge(2)W(18)Nb(8)O(88)]·18H(2)O (Cs(5)-3) and tetramer Cs(8)K(3)H(9)[Ge(4)W(36)Nb(16)O(166)]·27H(2)O (Cs(8)K(3)H(9)-4), through the formation of Nb-O-Nb bridges. Disassembly through the cleavage of Nb-O-Nb bonds from 4 to 2 and 1 was achieved by controlling the pH and by adding H(2)O(2), respectively. The transition from 1 to 2 can be achieved by simply adding H(2)O(2) to a solution of 1. All four compounds were characterized in the solid state by elemental analysis, infrared spectroscopy, thermogravimetry, and single-crystal X-ray diffraction. (183)W NMR analysis proved that the solid-state structures of polyanions 1-4 were retained after dissolution. Disassembly from 4 to 1 and 2 in solution was observed by (183)W NMR spectroscopy. The UV/Vis spectra of 1 at different pH confirmed that it is stable in the pH range of 0.1-14.0 at room temperature.

Coordination between [H2P2W12O48]12- and antimony(III): synthesis and characterization of sandwich complex derived from the new {P2W13O51} fragment.

A sandwich-type anionic cluster of a new lacunary building block [P(2)W(13)O(51)](14-) has been prepared: [H(6){P(2)W(13)O(51)}(2)Sb(4)](10-) (1) was synthesized in a one-pot self-assembly reaction of [H(2)P(2)W(12)O(48)](12-) with C(4)H(4)KO(7)Sb.0.5H(2)O and characterized by single-crystal X-ray analysis, IR, thermogravimetric analysis, elemental analysis, UV, NMR and electrochemistry. 1 represents the first dimetric, antimony-containing polyoxoanion derived from a vacant Dawson-type tungstophosphate.