Polyoxometalate tri-supported transition metal complexes containing mixed-valent transition metal ions

Three compounds, [AsMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·4H₂O (1), [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3H₂O (2) and [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3.5H₂O (3), have been synthesized under hydrothermal conditions and characterized by IR, UV–vis, XRD, TG, elemental analysis, and X-ray diffraction analysis. Single-crystal X-ray structure analysis reveals that 1 and 2 are isostructural and isomorphous, whereas 2 and 3 are polymorphs. Polymorphs of 1 have not been synthesized yet. The mixed-valent transition metal ion in 1–3 has been further confirmed by TG analyses. Catalytic properties of 1 and 2 have also been studied.     

Two new Keggin-type polyoxometalate-based organic-inorganic hybrid compounds with metal ions and chelate ligands

Two new hybrid compounds with chemical formulas [Co(L₁)₂(H₂O)₂]₂[SiW₁₂O₄₀]·6H₂O (1) and [Cu₂(C₉H₂₂ N)₂(L₂)₂][SiW₁₂O₄₀]·2H₂O (2) (L₁ = 3,3′-diamino-5,5′-bis(1H-1,2,4-triazole), L₂ = 1,2-bis(3-(2-pyridyl)pyrazole-1-ylmethyl)benzene, C₉H₂₂ N = tripropylamine) were prepared in a hydrothermal reaction system containing Keggin-type polyoxometalates (POMs), transition metal (TM) salts (cobalt salts and copper salts), and chelate L₁/L₂ ligands. X-ray structural analysis reveals that 1 and 2 possess 3-D supramolecular host frameworks with large cavities and the polyoxoanions SiW₁₂ reside in these cavities as the guest templates. The photocatalytic activities of 1 and 2 were investigated. Both compounds show efficient catalytic activity for degradation of RhB with 1 > 2. The loading amount of the POM units and the structural features of these POM-based organic-inorganic hybrid compounds may be necessary factors that affect the activity of catalysts in the photocatalytic degradation.     

pH-controlled assembly of two new supramolecular hybrid compounds based on Keggin polyoxotungstates

Two supramolecular compounds based on Keggin polyoxotungstates, (4,4′-H₂bpy){[Cu(4,4′-bpy)]₂[SiW₁₂O₄₀]} (1) and (4,4′-H₂bpy)₂[SiW₁₂O₄₀]·2H₂O (2) have been synthesized and characterized by elemental analyses, IR, UV, XPS spectra, TG analyses, and single crystal X-ray diffraction analyses. Compound 1 exhibits an infinite 1-D ladder like structure, which is further interconnected into a 3-D supramolecular framework via hydrogen bonding interactions. Compound 2 contains 4,4′-bipyridine (4,4′-bpy), pseudo-Keggin polyoxoanions [SiW₁₂O₄₀]^4?, and water molecules. Polyoxoanions together with water molecules in 2 construct a 3-D inorganic supramolecular network through O···O and O···Ow(1) interactions. The electrochemical behaviors and photocatalytic properties of 1 and 2 have been investigated.     

Two new hybrid compounds assembled from Keggin phosphotungstates,cobalt/zinc cations and V-shaped imidazole ligands

Two new inorganic–organic hybrid compounds, [Co(H₂O)₂(bimb)₂]₂[PW^VW^VI₁₁O₄₀] (1) and [Zn₃(H₂O)₄(bimb)₄][PW^V₃W^VI₉O₄₀] (2) (bimb = 1,3-bis(1-imidazoly)benzene) have been obtained and characterized by routine methods. Compounds 1 and 2 are synthesized under the same hydrothermal conditions except for alternation of the metal cations, however, their eventual structures are different. Compound 1 exhibits a 1D chain, whereas 2 shows a complicated 3D framework. The distinct structural features of the two compounds indicate that metal cations should have great effects on the structures of POM-based organic–inorganic hybrid compounds. The electrochemical properties of 1 and 2 have been also investigated, and the results show that 1 has a good electrocatalytic activity toward reduction of hydrogen peroxide (H₂O₂) molecules ascribed to W-centers.     

Hydrothermal syntheses and characterizations of two new hydrogen bond-supported supramolecular compounds based on polyoxometalates

Two new polyoxometalates [HN(C₂H₅)₃]₃[PMo₁₂O₄₀] (1) and [NH₂(C₂H₄NH₃)₂]₂[Mo₅P₂O₂₃] (2) have been hydrothermally synthesized and characterized by IR, UV-Vis, XPS spectra, TG analyses, and single crystal X-ray diffraction. Crystal data for 1: monoclinic, space group C2/c, a = 24.651(5) Å, b = 10.822(2) Å, c = 22.413(5) Å, β = 120.37(3)°, and V = 5158.7(18) ų; for 2: triclinic, space group P-1, a = 9.821(2) Å, b = 9.948(2) Å, c = 14.687(3) Å, α = 95.490(3)°, β = 98.870(3)°, γ = 95.710(3)°, and V = 1401.7(5) ų. The crystal structure analyses reveal complex hydrogen bonds in both 1 and 2 in 3-D supramolecular arrays constructed from different polyoxoanions and organic ligands.     

Hydrothermal assembly and luminescence property of lanthanide-containing Anderson polyoxometalates

Two compounds, {[Sm(H₂O)₅]₂(TeMo₆O₂₄)}·6H₂O (1) and {[Eu(H₂O)₇]₂ (TeMo₆O₂₄)}·5H₂O (2) have been synthesized by hydrothermal reactions and characterized by elemental analyses, IR spectra, thermal stability analyses, X-ray powder diffraction, and single-crystal X-ray diffraction. Compound 1 represents the first example of a 2D layer architecture constructed from Anderson-type polyoxoanions [TeMo₆O₂₄]⁶⁻ and rare-earth ions Ln³⁺. Compound 2 displays a 1D chain structure built up of alternating Anderson-type polyoxoanions [TeMo₆O₂₄]⁶⁻ and rare-earth ions Eu³⁺ along the c-axis. Luminescence measurement of 2 exhibits typical red fluorescent emission of the Eu³⁺ ion at room temperature. Furthermore, the emission is intense enough to be observed macroscopically under UV irradiation (365 nm).     

Hydrothermal synthesis and crystal structural characterization of two new modified polyoxometalates constructed of positive and negative metal–oxo cluster ions

Two new interesting polyoxometalate derivatives 1 and 2 constructed of modified metal–oxo cluster ions carrying positive and negative changes, respectively, was hydrothermally prepared and structurally characterized by IR, ESR, XPS, elemental analysis and X-ray crystallography. The result of structure determination shows that compound 1 and 2 are isostructural and both contain polyoxocation and polyoxoanion, and both cation and anion are built on mixed Mo–V tetra-capped pseudo-Keggin units with P centre, [Mo₈V₈O₄₀(PO₄)]ⁿ⁻, bonded to four or two [Ni(2,2′-bipy)₂H₂O]²⁺ complexes, respectively, via terminal oxygen of the capping V atoms. Magnetism measurement indicates that there exists antiferromagnetic interaction in complex 1 and 2.     

Two new halide-containing polyoxometalate-based compounds

Two new compounds, [CuCl(Phen)(H₂O)][PW₁₂O₄₀][4,4′-H₂bpy]·1.5H₂O (1) and [Cd₂(Phen)₄Cl₂][HPMo₁₂O₄₀](4,4′-bpy) (2) (bpy?=?bipyridine, Phen?=?phenanthroline), have been hydrothermally prepared and characterized by IR, UV–vis, XPS, XRD, elemental analysis, cyclic voltammetry analysis, and single-crystal X-ray diffraction analysis. Compound 1 exhibits a 1-D chain structure constructed from polyoxometalates (POMs) and transition metal complexes, whereas 2 presents a supramolecular structure constructed from POMs, metal halide clusters, and organic ligands.     

Two new hydrogen bond-supported supramolecular compounds assembly from polyoxovanadate and organoamines

Two novel organic-inorganic hybrid compounds based on organoamines and polyoxovanadates formulated as (H₂dien)₄[H₁₀V₁₈O₄₂(PO₄)](PO₄)·2H₂O (1) (dien=diethylenetriamine) and (Him)₈[HV₁₈O₄₂(PO₄)] (2) (im=imidazole) have been prepared under hydrothermal conditions by using different starting materials, and characterized by elemental analyses, IR, ESR, XPS, TGA and single-crystal X-ray diffraction analyses. Crystal data for compound 1: C₁₆H₇₄N₁₂O₅₂V₁₈P₂, Monoclinic, space group C2/c, a=23.9593(4) Å, b=13.0098(2) Å, c=20.1703(4) Å, β=105.566(3)°, V=6056.6(19) Å³, Z=4; for compound 2, C₂₄H₄₁N₁₆O₄₆V₁₈P, Tetragonal, space group I4/mmm, a=13.5154(8) Å, b=13.5154(8) Å, c=19.1136 Å, β=90°, V=3491.4(3) Å³, Z=2. Compound 1 consists of protonated diens together with polyoxovanadates [H₁₀V₁₈O₄₂(PO₄)]⁵⁻. Compound 2 is composed of protonated ims and polyoxovanadates [HV₁₈O₄₂(PO₄)]⁸⁻. There are hydrogen-bonding interactions between polyoxovanadates and different organoamines in 1 and 2. Polyoxovanadates are linked through H₂dien into a three-dimensional network via hydrogen bonds in 1, while polyoxovanadates are linked by Him into a two-dimensional layer network via hydrogen bonds in 2. The crystal packing patterns of the two compounds reveal various supramolecular frameworks.     

Two new organic-inorganic hybrid compounds based on metal-pyrazine coordination polymers and Keggin polyoxometalates: effect of metal ions on thestructure

Through changing the metal ions, two Keggin polyoxometalates-based hybrid compounds, [Cu₅(pz)₆(Cl)(SiW₁₂O₄₀)] (1) and [Ag₄(pz)₃(H₂O)₂(SiW₁₂O₄₀)] (2) (pz=pyrazine), were hydrothermally synthesized and characterized by an elemental analysis, IR spectroscopy, thermogravimetric analyses, and single X-ray diffraction. In compound 1, the metal-organic motif exhibits a 6³ topological 2-D sheet, which is further fused by the [SiW₁₂O₄₀]⁴⁻ anions to construct a (6·7·8)(6³·7·8²)(6³)(6⁵·7)(6⁵·8) topological 3D structure. In compound 2, the bridging groups Ag₂(pz) connect the [SiW₁₂O₄₀]⁴⁻ anions to form a (5³)₂(5⁴·8²) topological 2-D layer, which is further linked by an [Ag(pz)]_nⁿ⁺ chains to construct a 3D structure with the (3⁴·4¹⁶·5²⁴·6¹²·7⁸·8²)(3⁴·4⁶·5⁴·6)₂(4·5²)₂ topology. It represents the highest connected network topology presently known for the polyoxometalates system. The structure differences of compounds 1 and 2 reveal that the coordination numbers and geometries of the metal ions have a great influence on the final structure and topology of the Keggin POMs-based hybrid compounds. In addition, the electrochemistry properties of the two compounds have been studied.     

Two new hydrogen bond-supported supramolecular compounds assembly from arsenic vanadates and [M(H2O)6] cations (MCo, Ni)

Two new supramolecular compounds based on arsenic vanadates formulated as [H₂As₆V₁₅O₄₂(H₂O)][Co(H₂O)₆]₂·2H₂O (1) and [H₂As₆V₁₅O₄₂(H₂O)][Ni(H₂O)₆]₂·2H₂O (2) have been prepared by reacting V₂O₅, H₂C₂O₄·2H₂O, As₂O₃,·H₂SO₄, CoCl₂·6H₂O (NiSO₄·6H₂O) and enMe (enMe=1,2-diaminopropane) under mild hydrothermal conditions and characterized by elemental analyses, IR, ESR, XPS and single crystal X-ray diffraction analyses. Crystal structure analyses reveal that compounds 1 and 2 are isostructural and exhibit novel 2-D supramolecular layer structures constructed from arsenic-vanadium clusters and two different types of secondary building units (SBUs), respectively, the different SBUs are formed by joint of two adjacent [Co(H₂O)₆]²⁺ cations in compounds 1 and [Ni(H₂O)₆]²⁺ cations in 2, respectively.     

Syntheses and structural characterizations of three transition metal coordination complexes based on flexible 2,4-dichlorophenoxyacetate (2,4-DCP)

Three transition metal coordination complexes, {[Co(2,4-DCP)₂(μ ₂-H₂O)(H₂O)₂]?·?(H₂O)₂} _n (1), [Zn(2,4-DCP)(IN)] _n (2), and [Mn₂(2,4-DCP)₃(DMPY)₂(μ ₂-H₂O)(H₂O)]?·?(2,4-DCP)?·?0.2(H₂O) (3) (2,4-DCP?=?2,4-dichlorophenoxyacetate, IN?=?isonicotinate, DMPY?=?5,5′-dimethyl-2,2′-bipyridine), have been prepared under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a 1-D chain through cobalt and bridging water molecules with Co?···?Co distance of 4.028(2)?Å. Complex 2 shows a 2-D (4,4) net, which is extended into a 3-D supramolecular framework by weak hydrogen-bonding interactions. Complex 3 consists of discrete dinuclear cations, 2,4-DCP counter ions and free water molecules, which are assembled into a packing structure through π?···?π stacking of inversion-related DMPY ligands and hydrogen bonds. Magnetic susceptibility measurements show weak antiferromagnetic interactions in 1. The photoluminescence and lifetime of 2 in the solid state have also been studied.     

A series of new supramolecular structures constructed from triethylenediamine and different polyoxometalates

Three new supramolecular compounds based on triethylenediamine and different polyoxometalates [W^VI₃V^V₃O₁₉H]{[Cu(HDABCO)]₂(H₂O)} (1), [P₂Mo^VI₁₈O₆₂][HDABCO]₂[H₂DABCO]₂·12 H₂O (2) and [Mo^VI_7.5W^VI_0.5O₂₇][Cu(HDABCO)]₂·2 H₃O·2 H₂O (3) (DABCO=triethylenediamine) have been synthesized hydrothermally and characterized by IR, TG, XPS and X-ray diffraction analyses. Crystal structure analyses reveal that compound 1 exhibits a face-centered cubic packing motif, compound 2 displays a supramolecular structure constructed form the “chains” arranged hexagonally, compound 3 contains [Mo_7.5W_0.5O₂₇]_∞ chain decorated by [Cu(HDABCO)]²⁺ cations, which was then packed into a layer structure. These results show that the same organonitrogen combining with the different POMs will yield different supramolecular networks.     

Two lanthanide luminescent coordination compounds based on 3,5-pyrazoledicarboxylate and oxalic acid

Two isostructural 3-D complexes [Ln(pdc)(ox)_0.5(H₂O)₂]?H₂O (Ln = Tb(1), Eu(2); pdc = 3,5-pyrazoledicarboxylate; ox = oxalate) have been synthesized under hydrothermal conditions. Both are characterized by single crystal X-ray diffraction, elemental analysis, and IR. Compounds 1 and 2 possess a 3-D framework with 1-D rectangular channels built from 2-D, brick-like networks, and pdc ligands. The photoluminescence and lifetimes of 1 and 2 in the solid state have been studied.     

Two helical coordination polymers constructed from V-shaped and chelate ligands

The synthesis and X-ray characterization of two supramolecular isomers, [Co(oba)(2,2′-bpy)] _n (1 and 2) (oba?=?4,4′-oxybis(benzoate), 2,2′-bpy?=?2,2′-bipyridine) are reported. Crystal data for 1: a?=?12.026(2), b?=?15.120(3), c?=?11.361(2)?Å, β?=?91.46(3)°, Z?=?4, R ₁?=?0.0330, wR ₂?=?0.0949. Crystal data for 2: a?=?16.171(3), b?=?19.162(4), c?=?22.914(5)?Å, α?=?107.66(3), β?=?91.46(3), γ?=?98.99(3)°, Z?=?2, R ₁?=?0.0388, wR ₂?=?0.0456. They are conformational supramolecular isomers without solvent molecules in the structures, and exhibit different one-dimensional helical structures that are further assembled into distinct two-dimensional layers via π–π stacking interactions. The results indicate that the geometry of ligand is one of the most important factors for the construction of a helical motif.     

Hydrothermal synthesis and characterization of a new Anderson-type polyoxometalate

A new compound based on Anderson-type polyoxometalate, [Cu(phen)H₂O]₂[CrH₅Mo₆O₂₄]?·5H₂O (1) (phen?=?1,10-phenanthroline), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum, and thermal gravimetric analysis. Luminescent, electrochemical, and electroactivity properties of 1 have been studied.     

Syntheses, structures and properties of 3D inorganic-organic hybrid frameworks constructed from lanthanide polymer and Keggin-type tungstosilicate

Inorganic-organic hybrid frameworks, namely [Ce(H₂O)₃(pdc)]₄[SiW₁₂O₄₀]·6H₂O 1, [M(H₂O)₄(pdc)]₄[SiW₁₂O₄₀]·2H₂O (M=Ce for 2a, La for 2b, Nd for 2c; H₂pdc=pyridine-2,6-dicarboxylic acid) were assembled through incorporation of Keggin-type heteropolyanion [SiW₁₂O₄₀]⁴⁻ within the voids of lanthanides-pdc network as pillars or guests under hydrothermal condition. Single-crystal X-ray analyses of these crystals reveal that compound 1 presents 3D pillar-layered framework with the [SiW₁₂O₄₀]⁴⁻ anions located on the square voids of the two-dimensional Ce-pdc bilayer. Compounds 2a-c are isostructural and constructed from 3D Ln-pdc-based metal-organic framework (MOF) incorporating noncoordinating guests Keggin structure [SiW₁₂O₄₀]⁴⁻. Solid-state properties of compounds 1 and 2a-c such as thermal stability and photoluminescence have been further investigated.     

A novel 2D layer structure constructed from sandwich-type transition metal substituted tungstates and nickel coordination fragments: {[Ni(enMe)2]2[Ni(enMe)2(H2O)]2[As2W18Ni4(enMe)2O68]}·2H3O·2H2O

A novel polyoxometalate {[Ni(enMe)₂]₂[Ni(enMe)₂(H₂O)]₂[As₂W₁₈Ni₄(enMe)₂O₆₈]}·2H₃O·2H₂O (1) (enMe = 1,2-propylenediamine) has been synthesized and characterized, which is the first high-dimensional structure constructed from sandwich-type transition metal substituted tungstates and transition metal coordination groups.