Crystal structure of two salts derived from paratungstate in the [H2W12O42]10− anion

Novel mixed salts of the paratungstate anion Na₂(NH₄)₈[H₂W₁₂O₄₂]·12H₂O (1) and Na_7.5K_2.5[H₂W₁₂O₄₂]··22.2H₂O (2) are obtained by slow concentration of tungstate solutions and characterized by single crystal X-ray diffraction.     

Two Bisupporting Keggin-Type POM-Based Hybrids Decorated by [Zn(phen)2]2+ Fragments

Two bisupporting Keggin-type polyoxoanion-based hybrids decorated by [Zn(phen)₂]²⁺ complexes, [Zn(phen)₂]₂(PW ₁₁ ^VI W^VO₄₀) (1) and K[Zn(phen)₂(H₂O)]₂(OH) (SiW₁₂O₄₀)·H₂O (2) (phen = 1,10′-phenanthroline), have been hydrothermally synthesized, and characterized by elemental analysis, IR spectra, UV–Vis spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and single-crystal X-ray diffraction. The structural analyses reveal that compound 1 consists of a 0D bisupporting Keggin-type heteropoly blue cluster obtained by using reductant glucose, which is grafted by two [Zn(phen)₂]²⁺ fragments; compound 2 presents a 1D infinite chain, which is constructed from bisupporting [SiW₁₂O₄₀]^4? polyoxoanions decorated by [Zn(phen)₂(H₂O)]²⁺ fragments and K⁺ ions. Additionally, the electrochemical behaviors of two compounds were studied.     

Keggin-Type Polyoxometalate Cluster Functionalized with Dinuclear M-H2biim (M = Cu, Ag) Metal–Organic Segments

Three inorganic–organic hybrid complexes, [Cu₂(H₂biim)₂(OH)₂]₂(SiW₁₂O₄₀)·2H₂O (1), [Cu₂(H₂biim)₂]₂(SiW₁₂O₄₀)·2H₂O (2) and [Ag₂(H₂biim)₂]₂(SiW₁₂O₄₀)·2H₂O (3) (H₂biim = 2, 2′-biimidazole), have been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, PXRD, TG and single-crystal X-ray diffraction. The crystallographic analysis reveals that in compounds 1–3, the Keggin polyanions [α-SiW₁₂O₄₀]^4? act as inorganic building blocks, which are linked with the dinuclear metal–organic units via Cu–O bonds in compound 1, or through supramolecular interactions in compounds 2 and 3. Compound 1 shows a 3D supramolecular structure constructed by net-like layers. Compounds 2 and 3 display 2D layer structures which were composed of wave-like chains. In addition, these compounds show electrochemical activities, and photoluminescence properties are measured in the solid state.     

Synthesis, crystal structure, and property of one- and two-dimensional complexes based on paradodecatungstate-B cluster

Three polyoxotungstates, Na₈[Cu(H₂O)₂(H₂W₁₂O₄₂)]·30H₂O (1), Na₈[Cd(H₂O)₂(H₂W₁₂O₄₂)]·20H₂O (2), and Na_7.4[Cd_1.3(H₂O)₂(H₂W₁₂O₄₂)]·24H₂O (3), were synthesized and characterized by elemental and thermogravimetric (TG)analysis, infrared spectroscopy and X-ray single-crystal analysis. Both complexes 1 and 2 exhibit one-dimensional structure with two neighboring paradodecatungstate-B clusters, [H₂W₁₂O₄₂]¹⁰⁻, linked by [Cu(H₂O)₂]²⁺ or [Cd(H₂O)₂]²⁺ units, while complex 3 displays a two-dimensional network structure. The electrochemical behaviors of complexes 1 and 3 were investigated in the buffer solution of pH 4.8. The results of electrocatalysis reveal that the reduced species of complexes 1 and 3 are electrocatalytically active for the reduction of nitrite. Complex 1 exhibits the electrocatalytic activity for the reduction of nitrate as well. The surface photovoltage spectroscopy (SPS) and electric field-induced SPS (EFISPS) measurements show that the surface photovoltage behavior of complex 1 is complicated while complex 3 bears the property of n-type semiconductor.     

Honeycomb-like layers constructed by hydrogen bonds. Synthesis, structure, and property of two new supramolecular compounds based on polyoxotungstate

Two new compounds based on polyoxotungstate [Co₂(PCA)₄(H₂O)₆][SiW₁₂O₄₀]·8H₂O (1), [Cd₂(PCA)₄(H₂O)₆][SiW₁₂O₄₀]·8H₂O (2) (PCA = pyridine-4-carboxylic acid) are prepared and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and thermal analysis. The results of the single crystal X-ray diffraction analysis reveal that 1 and 2 are isomorphic and two water molecules in the compounds act as the bridging groups of two cobalt or cadmium atoms, forming dinuclear coordination cations. The ligand PCA adopts a monodentate coordination mode and its uncoordinated carboxyl oxygen atom and the protonized nitrogen atom form hydrogen bonds with other ligands, by which the cations are linked into a supramolecular 2D network with hexagonal grids. The polyoxotungstate anions are arranged above and below the cationic grids. A strong emission peak at 420 nm of 2 is attributed to a ligand-metal transition.     

A flexible chelate ligand in dodecatungstoborate-based supramolecular compounds

Two new dodecatungstoborate-based supramolecular compounds, [Cu₄(H₂EGTA)₂(H₂O)₄(HBW₁₂O₄₀)]·18H₂O (1) and [Na₃(H₂O)₆Ca₃(H₂O)₆(HEGTA)₂] [H₂BW₁₂O₄₀]·21H₂O (2) (EGTA = ethyleneglycol-bis-(2-aminoethylether)-tetra acetate anion), were synthesized in aqua solution and characterized by element analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction technique. The results show that in 1 two H₂EGTA^2? anions bond to four Cu²⁺ ions forming a four-nuclear cyclic cation, Cu₄(H₂EGTA)₂(H₂O) ₄ ⁴⁺ ; and dodecatungstoborate anion HBW₁₂O₄₀ ^4? acting as a bidentate ligand links two four-nuclear cations, leading to one-dimensional chain extending along [101] direction, [Cu₄(H₂EGTA)₂(H₂O)₄(HBW₁₂O₄₀)] _n (Cu–EGTA–BW₁₂). In 2 two HEGTA^3? anions coordinate to four Ca²⁺ ions in different modes, forming a Ca-EGTA polymeric chain. The building blocks (Cu–EGTA–BW₁₂ chains in 1, Ca–HEGTA chains and BW₁₂ anions in 2) are fused into three-dimensional architectures by hydrogen bonds. Variable temperature magnetic susceptibilities of 1 were determined and the results show that in 1 there is a weak ferromagnetic interaction.     

Synthesis and Characterization of a 3-D Framework Constructed from [V12B18O54(OH)6(H2O)]10− Clusters and K+ Cations

An organic–inorganic hybrid polyoxovanadoborate K₆(CH₃NH₃)₄[V₁₂B₁₈O₅₄(OH)₆-(H₂O)]·2en·12H₂O (1, en = ethylenediamine) has been synthesized under hydrothermal conditions and characterized by IR spectroscopy, element analyses, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Single-crystal structure analysis reveals that 1 consists of a cage-like polyoxovanadium borate [V₁₂B₁₈O₅₄(OH)₆(H₂O)]^10? cluster that is constructed from a puckered {B₁₈O₃₆(OH)₆} ring sandwiched by two triangle {V₆O₁₈} units, in which a water molecule is confined in the middle of the cage-like cluster. Interestingly, 1 represents the rare example of extended 3-D framework constructed from [V₁₂B₁₈O₅₄(OH)₆-(H₂O)]^10? clusters through K⁺ cations.     

Coordination polymer with the framework structure [Zn2(DMA)(Atc)] · DMA: Synthesis, structure, and properties

Crystals of a new coordination polymer with the framework structure, [Zn₂(DMA)(Atc)] · DMA (I), were prepared by heating a solution of Zn(NO₃)₂ · 6H₂O and H₄Atc (H₄Atc is 1,3,5,7-adamantanetetracarboxylic acid) in N,N′-dimethylacetamide (DMA). Colorless crystals of Zn₂(Atc) · 2MeOH · 4H₂O (II) were obtained by soaking the crystals of compound I in methanol. The structure of compound I was determined by X-ray diffraction analysis. Compounds I and II were characterized by X-ray powder diffraction, IR spectroscopy, thermal gravimetric analysis, and elemental analysis. The luminescence properties of compound I were studied.     

Organic–inorganic hybrid complexes based on a Keggin-type polyoxoanion

Two organic?Cinorganic hybrid complexes based on a Keggin-type polyoxoanion, namely [Ni₂(H₂O)₂(bipy)₄(Hbipy)][AlW₁₂O₄₀]·7H₂O 1 and [Ni₂Cl₂(bipy)₃(Hbipy)₂][SiW₁₂O₄₀]·2.5H₂O 2 (bipy?=?4,4??-bipy), have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complexes 1 and 2 possess similar 2D layer structures, constructed from 1D zigzag chains {Ni(bipy)} _n ²ⁿ⁺ and alternatively arranged Keggin anion and bipy linkers. Photocatalytic investigations indicate that both 1 and 2 exhibit photocatalytic activity for the degradation of Rhodamine B.     

Synthesis and crystal structure of the complex [Mg(H2O)2(dmf@CB[6])(bdc)]·DMF·4H2O and the inclusion compound [dmf@CB[6]]·8H2O

The complex [Mg(H₂O)₂(dmf@CB[6])(bdc)]·DMF·4H₂O (1) and the inclusion compound [dmf@CB[6]]·8H₂O (2) were obtained from a mixture of magnesium perchlorate and water (for compound 1) or magnesium oxide and H₂SO₄ (for compound 2), and cucurbit[6]uryl (CB[6]) in the presence of N,N-dimethylformamide (DMF) with the additives of terephthalic or fumaric acid, respectively. X-ray diffraction studies showed that magnesium cation in compound 1 coordinated two oxygen atoms of the CB[6] molecule, one oxygen atom of the terephthalate anion, two molecules of water, and a DMF molecule located inside the cucurbit[6]uryl cavity. When fumaric acid was used instead of terephthalic acid under similar conditions of synthesis, no coordination of magnesium cations to cucurbit[6]uryl molecules took place, rather an inclusion compound of DMF into the macrocyclic cavitand was formed. Compounds 1 and 2 were characterized by X-ray diffraction data, IR spectroscopy, and elemental analysis.     

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.     

Supramolecular Assembly Based on Octamolybdate and Triazole Derivative: Crystal Structure and Catalytic Application in Olefin Epoxidation

A novel polyoxometalate-based compound, [H(atrz)]₄[(atrz)₂(Mo₈O₂₆)]·2H₂O (1) (atrz = 3-amino-1,2,4-triazole), has been synthesized by traditional hydrothermal method, and characterized by means of elemental analysis, FT-IR spectroscopy, Powder X-ray diffraction and single-crystal X-ray. The compound 1 contains a 2D supramolecualr layer which is constructed from [(atrz)₂(γ-Mo₈O₂₆)]^4? units via intermolecular hydrogen-bonding interactions. Furthermore, the adjacent 2D layers are packed together through the aromatic π?π stacking interactions and exhibits a 3D supramolecular structure. The catalytic properties of 1 were investigated in olefin epoxidation with tert-butylhydroperoxide (t-BuOOH) as the oxidant. It was found that compound 1 could serve as active and stable heterogeneous catalyst for the epoxidation of cyclooctene and 1-octence. Besides, introducing copper ions into compound 1 could further improve the catalytic activity for olefin epoxidation.     

Hydrothermal Syntheses and Structural Characterization of Two 3-D Supramolecular Networks Constructed from Tetra-CoII Sandwiched Polyoxometalates

Two Co₄-substituted sandwich-type polyoxometalates (H₂en)₉[Co₄(H₂O)₂(PW₉O₃₄)₂]{[Co(H₂O)₄][Co₄(H₂O)₂(PW₉O₃₄)₂]}·18H₂O (1) and (H₂en)₅[Co₄(H₂O)₂(H₃GeW₉O₃₄)₂]{[Co(H₂O)₄]₂[Co₄(H₂O)₂(H₂GeW₉O₃₄)₂]}·16H₂O (2) (en = ethylenediamine) have been hydrothermally synthesized and characterized by IR spectra, elemental analyses, thermogravimetric analyses, powder X-ray diffraction and single-crystal X-ray diffraction. Single-crystal structure analysis reveals that the molecules of 1 and 2 contain two Co₄-substituted sandwich-type polyoxoanions. This type of a molecular unit containing double polyoxoanions is very rare. From the viewpoint of supramolecular chemistry, the sandwich-type polyoxoanions in 1 and 2 can be further extended to 3-D frameworks via extensive hydrogen-bonding interactions.     

Synthesis, crystal structure and electrochemical behavior of supramolecular complex [4, 4′-bipyH2][4, 4′-bipyH]2.5(P2Wl8O62)[4, 4′-bipyH1.5] · 2H2O

A Dawson-type supramolecular complex [4, 4′-bipyH₂][4, 4′-bipyH]_2.5 (P₂W_l8O₆₂)[4, 4′-bipyH_{1. 5}] · 2H₂O (1) has been synthesized hydrothermally and determined by means of IR, UV, cyclic voltammetry (CV) and X-ray single-crystal diffraction methods. Single crystal X-ray structural analysis reveals that the compound 1 exhibits 1D chains constructed from polyanions and 4, 4′-bipy molecules connected together by hydrogen bonds and weak contact. The 1D chains are assembled into 2D networks by weak contacts, and the intermolecular interaction of “water chains” is robust enough to really act as a “supramolecular glue” to assemble the 2D networks into 3D arrays. CV study reveals that compound 1 exhibits four chemically reversible processes.     

Synthesis and Structure of [Co2Bi2(α or β-Β-CoW9O34)2]14− Isomers and Their Catalytic Water Oxidation

A new sandwich-type complex based [α-Β-CoW₉O₃₄]^12? as ligand, Na₉H₅[Co₂Bi₂(α-Β-CoW₉O₃₄)₂]·54H₂O 2, has been synthesized and characterized structurally by elemental analysis, single-crystal X-ray diffraction, IR, XRD and TG. Structural analysis indicates that the anion of 2 is isomeric with that of Na₁₄[Co₂Bi₂(β-Β-CoW₉O₃₄)₂]·48H₂O 1. It is constructed through sandwiching Bi^III and Co^II ions with [α-B-Co^IIW₉O₃₄]^12? anions. Cyclic voltammetry experiments are carried out in 50 mM sodium phosphate buffer (pH = 7.4) containing 1 mM [Ru(bpy)₃]²⁺ solution. It is found that both 1 and 2 exhibit catalytic activity of the electrochemical oxidation of H₂O into O₂. Visible-light-induced catalytic activity of 1 and 2 are investigated by using [Ru(bpy)₃]²⁺ as a photosensitiser and S₂O₈ ^2? as a sacrificial electron acceptor. In 40 min, 16.8 and 5.3 μmol of O₂ are produced for 1 and 2 respectively.     

Synthesis and structure of chiral coordination polymers of CoII, CuII, and MgII saccharates

Chiral metal-organic coordination polymers [Co₂(sacch)₂]·1/₂H₂O·CH₃OH (1), [Cu(sacch)(H₂O)₂]·3H₂O (2), and [Mg(H₂O)₃(sacch)] (3) (H₂sacch is d-saccharic acid) were synthesized from aqueous or water-methanol solutions of potassium hydrogen saccharate and a salt of the corresponding metal. The compositions and structures of the resulting compounds were determined by single-crystal X-ray diffraction and confirmed by X-ray powder diffraction, IR spectroscopy, thermogravimetry, and elemental analysis.     

Temperature-Dependent Organic Functionalization of {Ni6PW9} Species: from Isolated Clusters to 1D Chain

Four new hexa-nickel(II)-substituted Keggin-type tungstophosphates [Ni₆(μ₃-OH)₃(oeen)₃(H₂O)₃(B-α-PW₉O₃₄)]·6H₂O (1, oeen = N-(2-hydroxyethyl)enediamine), [Ni₆(μ₃-OH)₃(oeen)₃(H₂O)₄(B-α-PW₉O₃₄)]₂·13H₂O (2), [Ni₆(μ₃-OH)₃(oeen)₂(tran)(H₂O)₃(B-α-PW₉O₃₄)]·3H₂O (3, tran = 1,4,7-triazonane) and [Ni₆(μ₃-OH)₃(oeen)₂(tran)(H₂O)₂(B-α-PW₉O₃₄)]·6H₂O (4) have hydrothermally made by controlling their reaction temperatures. 1–4 have been characterized by elemental analyses, IR spectra, powder X-ray diffraction, thermogravimetric analyses and single-crystal X-ray diffraction, respectively. Structural analyses reveal that they consist of {Ni₆(μ₃-OH)₃(H₂O) _n }⁹⁺ cores and B-α-PW₉O₃₄ (PW₉) units, and further are stabilized by organic neutral oeen/tran molecules. 1–3 are isolated clusters while 4 is the 1D chain structure. It should be noted that the tran molecules in 3 and 4 are derived from the oeen molecules in the starting materials.     

Synthesis and structures of copper(II) and cadmium(II) compounds based on pyridazine derivative ligands

The two new compounds [Cu(HODA)₂(H₂O)₂] · 3H₂O (I) and [Cd(HODA)₂(H₂O)₃] (II) (HODA = 6-oxo-1,6-dihydropyridazine-4-carboxylic acid) based on pyridazine derivation ligands have been synthesized and characterized by elemental analysis, infrared spectrum and X-ray single crystal diffraction. X-ray analysis shows that in compound I, Cu²⁺ ion is four-coordinated with a plane square geometry while Cu²⁺ ion in compound II is seven-coordinated with a distorted pentagonal bipyramid geometry. Both of the two units are all connected as 3D supramolecular structures by the intermolecular hydrogen bonds. Moreover, thermal gravimetric analysis of two compounds has been also investigated.     

The Oxalato-Titanium-Containing Tungstophosphate(V) Dimers, [Ti8(C2O4)8P2W18O76(H2O)4]18− and [Ti6(C2O4)4P4W32O124]20−

The oxalato-titanium(IV)-containing, dimeric 18-tungsto-2-phosphate [Ti₈(C₂O₄)₈P₂W₁₈O₇₆(H₂O)₄]^18? (1) and the 32-tungsto-4-phosphate [Ti₆(C₂O₄)₄P₄W₃₂O₁₂₄]^20? (2) are formed upon reaction of the oxalato-titanium complex [TiO(C₂O₄)₂]^2? with the trilacunary Keggin precursor [A-α-PW₉O₃₄]^9? and the hexalacunary Wells–Dawson precursor [H₂P₂W₁₂O₄₈]^12?, respectively. Polyanion 1 consists of two {PW₉} units encapsulating eight titanium centers and connected to each other via two Ti–O–Ti bridges, and crystallizes as a mixed potassium-sodium-lithium salt in the triclinic space group $P{\bar{1}}$ . Polyanion 2 comprises two {P₂W₁₆} units containing each two titanium atoms, and the two half-units are connected via two titanium atoms decorated by two oxalate groups each, and crystallizes as a mixed potassium-lithium salt in the rhombohedral space group $R{\bar{3}}c$ . Polyanions 1 and 2 were characterized in the solid state by single-crystal XRD, FT-IR, and TGA, whereas polyanion 2 was also investigated by ³¹P and ¹⁸³W NMR.     

Arsenic-Centered Molybdenum–Vanadium Polyoxometalate Supporting Three Copper Complexes

A novel compound [HMo ₈ ^VI V ₆ ^V As^VO₄₂][Cu(2,2′-bpy)₂]₂[Cu(2,2′-bpy)]·2H₂O (2,2′-bpy = 2,2′-bipyridine) 1 has been hydrothermally synthesized and structurally characterized by elemental analyses, infrared spectroscopy, ultraviolet spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and single crystal X-ray diffraction. Crystal structure analysis reveals that compound 1 is a bi-capped As/Mo/V Keggin polyoxometalate tri-supported copper complexes, and exhibits an extended three-dimensional supramolecular network via hydrogen-bonding and π–π stacking interactions. The electrochemical and magnetic properties of compound 1 have been studied.