Modular Molecules: Site‐Selective Metal Substitution,Photoreduction, and Chirality in Polyoxometalate Hybrids

The first members of a promising new family of hybrid amino acid–polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium‐tungstoarsenate structural backbone, followed by crystallization with p‐methylbenzylammonium (p‐MeBzNH₃⁺) cations, affords (p‐MeBzNH₃)₆K₂(GlyH)[As^III₄(Y^IIIW^VI₃)W^VI₄₄Y^III₄O₁₅₉(Gly)₈‐ (H₂O)₁₄] ? 47 H₂O ( 1 ) and enantiomorphs (p‐MeBzNH₃)₁₅(NleH)₃ [As^III₄(Mo^V₂Mo^VI₂)W^VI₄₄Y^III₄O₁₆₀(Nle)₉(H₂O)₁₁][As^III₄(Mo^VI₂W^VI₂)‐ W^VI₄₄Y^III₄O₁₆₀(Nle)₉(H₂O)₁₁] (generically designated 2 : L ‐Nle, 2 a ; D ‐Nle, 2 b ). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site‐selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small‐angle X‐ray scattering studies confirm maintenance of the structure of the polyanions of 2 , while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties.     

Synthesis,Structure and Property of a Dawson-type Arsenomolybdate with an Appended AsIII Cap

An inorganic–organic hybrid compound, (H₂bpy)₃[As^IIIAs₂ ^VMo₁₅ ^VIMo₃ ^VO₆₂]·3H₂O (bpy: 4,4′-bipyridine) (1) has been synthesized under hydrothermal conditions and characterized by elemental analysis, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction, IR spectrum, UV–Vis spectrum, thermogravimetric analysis and single-crystal X-ray diffraction. The crystallographic analysis reveals that compound 1 is composed of a Wells–Dawson polyoxoanion [As₂ ^VMo₁₅ ^VIMo₃ ^VO₆₂]^9? with the mixed valence of Mo^V,VI, which acts as a tetradentate ligand coordinating with the As^III cation to form the mixed valence As^III,V containing arsenomolybdate with the single cap structure in a chelate coordination mode. In the solid state, compound 1 shows a 3D supramolecular structure through hydrogen-bonding interactions (C–H···O, N–H···O, N–H···N). In addition, compound 1 exhibits reversible multi-electron redox processes and effective electrocatalytic activities towards the reduction of H₂O₂, NaNO₂ and KBrO₃. Moreover, compound 1 is used as a reducing agent of the graphene oxide to prepare graphene by a green chemistry type one-step synthesis method, which is characterized by XPS, Raman spectroscopy, PXRD, IR, scanning electron microscopy and transmission electron microscopy.     

The Hybrid Organic–Inorganic Assemblies Based on Monocapped Trivacant Keggin Arsenatomolybdate and Cu<Superscript>I</Superscript>-Organic Units

A new arsenomolybdate compound [Cu(imi)₂]₅Na[(AsO₄)Mo₉O₂₇(AsO₃)]·5H₂O(imi = imidazole) 1, has been prepared by hydrothermal method and structurally characterized by elemental analysis, IR, XRD, TG analysis and single-crystal X-ray diffraction analysis. Compound 1 represents the first example of monocapped trivacant Keggin [As^IIIAs^VMo₉O₃₄]^6? subunit as polydentate ligand bonded to five [Cu(imi)₂] complexes through one covalent bond and four weak Cu···O bonds. The electrochemical behavior of 1-modified carbon paste electrode has been studied in detail. In addition, photoluminescence and photocatalysis properties of 1 have been investigated.     

Two organic–inorganic hybrid compounds constructed from [PMoV1MoVI7VIV2VV4O42]4− and different transition metal fragments

Two new organic–inorganic hybrid compounds, [Cu(phen)(prz)]₂[PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]·4H₂O (1) and [Ag₂(phen)₄]₂[PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂] (2) (phen = 1,10-phenanthroline, prz = pyrazine), have been synthesized and characterized by IR, XPS, XRD, UV–vis, fluorescent spectra analyses, elemental analyses, X-ray diffraction analyses, TG analyses, and cyclic voltammetric measurements. Both compounds are formed by Keggin POM cores and transition metal fragments. Compound 1 exhibits an unprecedented 1-D chain structure constructed from [PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]^4? and [Cu(phen)(prz)]²⁺ in the –A–B↑–C–B↓– linking mode. Compound 2 shows a supramolecular structure formed by [PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]^4? and [Ag₂(phen)₄]²⁺.     

Influence of Coordination Geometry on the Ring Opening of Benzoxazine: Oxidovanadium(V), Dioxidomolybdenum(VI) and Dioxidotungsten(VI) Complexes of Benzoxazine Based Ligands and their Bio Inspired Catalytic Applications

Mono benzoxazine appended N-capped amino bis(disubstitutedphenol) ligands [ II ( a–c )] upon reaction with V^VO(OEt)₃ in a 1 : 1 molar ratio in EtOH/MeOH give [{V^VO}en(3,5-dtbb)₃] ( 1 ), [{V^VO}en(3-tb,5-mb)₃] ( 2 ) and [{V^VO}en(3,5-dmb)₃] ( 3 ). During the reaction, the benzoxazine ring opens with the loss of methylene group and the newly formed ligands, N,N-bis(2-hydroxy-3,5-disubstitutedbenzyl)-N’-2-hydroxy-3,5-disubstituted benzyledene-1,2-diaminoethane [ III ( a–c )], behave as tribasic pentadentate in these complexes. Under similar conditions, when [M^VIO₂(acac)₂] (M=Mo or W; Hacac=acetylacetone) reacts with II ( a–c ), these ligands retain their identity and form cis-[M^VIO₂] complexes, [{Mo^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 4 ), [{Mo^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 5 ) and [{Mo^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 6 ), [{W^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 7 ), and [{W^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 8 ). However, the benzoxazine ring ruptures in case of ligand IIc under these conditions and form [{W^VIO₂}{en(3,5-dmb)₃}] ( 10 ), similar to complexes 1–3 . Complex [{W^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 9 ), having structure similar to 4–8 , could only be obtained when the reaction was carried out in toluene. Not only 9 , even complexes 4–8 can be isolated in toluene. Rupturing of both benzoxazine rings has also been experienced when ligands 1,2-bis(6,8-disubstitutedbenzo[e][1,3]oxazin-3(4H)-yl)ethane [ I ( a–c )] react with [M^VIO₂(acac)₂] (M=Mo or W) in MeOH and give salan type complexes [(M^VIO₂)en(3,5-dtbb)₂] [M=Mo ( 11 ), M=W ( 14 )], [(M^VIO₂)en(3-tb,5-mb)₄] [M=Mo ( 12 ), M=W ( 15 )] and [(M^VIO₂)en(3,5-dmb)₄] [M=Mo ( 13 ), M=W ( 16 )]. Complexes 1–9 have been used as catalyst for the multicomponent Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) and oxidative bromination of phenol derivatives.     

Hydrothermal synthesis and crystal structure of a 1-D compound constructed from molybdovanadate clusters [V2Mo6O26]6− and copper complexes

A 1-D organic–inorganic hybrid compound, {Cu(en)₂}[V₂Mo₆O₂₆{Cu(en)₂}₂] · 4H₂O [en = ethylenediamine] (1), was hydrothermally synthesized and characterized by IR, UV spectroscopy, TG/DTA analyses, and single crystal X-ray diffraction. The X-ray crystallography analysis reveals an infinitely extended 1-D chain constructed from a molybdovanadate cluster [V₂Mo₆O₂₆]^6? as a building unit, two copper(II) complex fragments, {Cu(en)₂}²⁺, as attached groups and a copper(II) fragment, {Cu(en)₂}²⁺, as a bridging group. Each chain links to adjacent chains through weaker secondary Cu–O interactions forming an interesting 3-D supramolecular architecture.     

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-dimensional layer polyoxometalate-based inorganic metal–organic hybrid supramolecular networks woven by Cu ··· Opolyoxoanion short contact weak interactions

Two polyoxometalate-based inorganic metal-organic hybrid supramolecular complexes [Cu(2,2′-bpy)₂]₂[V^IV ₂Mo^V ₅Mo^VI ₇O₃₈(PO₄)] (1) (2,2′-bpy?=?2,2′-bipyridine) and [Cu(2,2′-bpy)₂]₂[Mo^VMo^VI ₁₁O₃₆(PO₄)]?·?3H₂O (2), have been hydrothermally prepared and structurally characterized by single-crystal X-ray diffraction. Both complexes are constructed from polyoxoanions (the bivanadyl capped α-Keggin polymolybdate anion [V^IV ₂Mo^V ₅Mo^VI ₇O₃₈(PO₄)]^4? for 1 and the reduced 12-molybdophosphate anion [Mo^VMo^VI ₁₁O₃₆(PO₄)]^4? for 2) and copper(II) complex cations [Cu(2,2′-bpy)₂]²⁺, forming two-dimensional (2D) layer network structures, in which the polyoxoanion and the complex fragment cation connect with each other through Cu?···?O_polyoxoanion short contact weak interactions, which mediate ferromagnetic interaction.     

A Bicapped α‐Keggin Unit‐Supported Transition Metal Complex: Hydrothermal Synthesis and Characterization of [Cu(en)2(H2O)]2[Cu(en)2]0.5[Mo8V7O42{Cu(en)2}]

A new metal‐oxo cluster supported transition metal complex, [Cu(en)₂(H₂O)]₂[Cu(en)₂]_0.5[Mo^VI₈V^IV₆V^VO₄₂{Cu(en)₂}], has been synthesized under hydrothermal conditions. Its structure was determined by single‐crystal X‐ray diffraction. The compound crystallizes in the triclinic system, space group (No. 2), a = 12.245(5), b = 12.669(5), c = 20.949(8) Å, α = 77.120(13), β = 78.107(17), γ = 65.560(14)°, V = 2860(2) ų, Z = 2. The metal‐oxo cluster contains a novel bicapped a‐Keggin structure unit and a [Cu(en)₂]²⁺ unit covalently bonded to the [Mo₈V₇O₄₂]^7? cluster.     

Effect of the central metal on coordination of 1,10-phenanthroline-5,6-dione in Keggin-based hybrid compounds

Two new Keggin-based hybrid compounds, [Cu₂(pdon)₃][PMo^VI ₁₁Mo^VO₄₀]·3H₂O (1) and [Mn₂Cl(H₂O)₂(pdon)₄][PMo₁₂O₄₀]·2H₂O (2) (pdon = l, l0-phenanthroline-5,6-dione) (pdon), were synthesized under hydrothermal conditions. By using different metal ions and tuning the ratio of metal to ligand, pdon shows different coordination modes. In compound 1, pdon with three kinds of coordination modes link Cu^II ions to form a 1D wave chain and Keggin-type polyanions [PMo^VI ₁₁Mo^VO₄₀]^4? fringe this 1D chain; hydrogen bonding interactions extend these 1D chains into a 2D supramolecular network. Compound 2 exhibits a discrete structure, in which pdon shows a single chelating coordination. Electrochemical properties of the title compounds have been investigated.     

Synthesis and Electrochemical Properties of a New 1D Organic–Inorganic Hybrid Compound Based on Keggin-Type Heteropolyanions and Isopolyanions Decorated by Transition Metal Fragments

A new chain-like organic–inorganic hybrid compound composed of the heteropolyanions and isopolyanions, [{Cu^II(2,2′-bpy)}₆(Mo^VMo^VI ₅O₂₂)] [PMo^VI ₁₂O₄₀] · H₂O 1 (bpy = 2,2′-bipyridine) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, XPS spectrum and single-crystal X-ray diffraction. Crystal data for compound 1: monoclinic, space group P _2(1)/c, a = 13.9382(14) Å, b = 20.0300(19) Å, c = 17.1757(17) Å, β = 94.054(2)°, V = 4783.2(8) ų, Z = 2. The Keggin-heteropolyanion [PMo₁₂O₄₀]^3? and the Cu-supporting isopolyanion [{Cu(2,2′-bpy)}₆(Mo₆O₂₂)]³⁺ building units are bridged through the O–Cu–O bridges into 1D infinite chain. Note that, the [{Cu(2,2′-bpy)}₆(Mo₆O₂₂)]³⁺ unit, which contains a rarely reported isopolyanion [Mo₆O₂₂]^9? decorated by six [Cu(2,2′-bpy)] fragments. Furthermore, the electrochemical behavior of a 1-modified carbon paste electrode (1-CPE) and its electrocatalytic reduction of nitrite were investigated.     

Two Novel 1-D Organic–Inorganic Composite Phosphotungstates Constructed from [Ln(α-PW11O39)2]11− Units and [Cu(en)2]2+ Bridges (Ln = CeIII/ErIII)

Abstract  Two novel organic–inorganic composite phosphotungstates, [H₉{Ce(α-PW₁₁O₃₉)₂}Cu(en)₂] · 6H₂O (1) and H₇[Cu(en)₂{Er(α-PW₁₁O₃₉)₂}Cu(en)₂] · 12H₂O (2) (en = ethylenediamine) have been synthesized by the hydrothermal reaction of the trivacant Keggin polyoxoanion [α-A-PW₉O₃₄]⁹⁻ with Ce^III or Er^III ions in the presence of Cu²⁺ ions and en, and structurally characterized by IR spectra, elemental analysis and thermogravimetric analysis. X-ray crystallographic analyses indicate that they are all built by sandwich-type [Ln(α-PW₁₁O₃₉)₂]¹¹⁻ (Ln = Ce^III, Er^III) polyoxoanions and [Cu(en)₂]²⁺ cations generating infinite one-dimensional arrangements. To our knowledge, this 1-D chain structures constituted by mono-Ln sandwiched POM units and transition-metal complex cations are very rare. Graphical Abstract  Two novel organic–inorganic composite phosphotungstates, [H₉{Ce(α-PW₁₁O₃₉)₂}Cu(en)₂] · 6H₂O (1) and H₇[Cu(en)₂{Er(α-PW₁₁O₃₉)₂}Cu(en)₂] · 12H₂O (2) (en = ethylenediamine) have been synthesized by the hydrothermal reaction of the trivacant Keggin polyoxoanion [α-A-PW₉O₃₄]⁹⁻ with Ce^III or Er^III ions in the presence of Cu²⁺ ions and en, and structurally characterized by IR spectra, elemental analysis and thermogravimetric analysis. X-ray crystallographic analyses indicate that they are all built by sandwich-type [Ln(α-PW₁₁O₃₉)₂]¹¹⁻ (Ln = Ce^III, Er^III) polyoxoanions and [Cu(en)₂]²⁺ cations generating infinite one-dimensional arrangements. To our knowledge, this 1-D chain structures constituted by mono-Ln sandwiched POM units and transition-metal complex cations are very rare.      

Two new transition-metal complexes (TMCs)-templated three-dimensional supramolecular networks based on tungstovanadophosphates

Two new polyoxometalates [Ni(phen)₃][Ni(en)₃][Ni(en)₂(H₂O)₂][Ni(en)₂]_0.5[PW^VI₇W^V₂V^IV₃O₄₀(V^IVO)₂]·6H₂O (1) and [Ni(phen)₃]₂[Ni(en)₂]Na[PW^VI₇W^V₂V^IV₃O₄₀(V^IVO)₂]·8H₂O (2) (en=ethylenediamine, phen=1,10-phenanthroline) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, EPR, XPS, elemental analysis and thermogravimetry. Their structures exhibit interesting 3D supramolecular networks, and contain new bicapped (pseudo-) Keggin-type tungsten-vanadium cluster and the template transition-metal complexes (TMCs) being generated in situ under mild hydrothermal conditions. Interestingly, compound 1 contains four different kinds of nickel complex countercations.     

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.     

Hydrothermal synthesis and structures of organic–inorganic hybrid solids based on arsenic-vanadate building blocks

Four novel organic–inorganic hybrid arsenic-vanadate complexes, [Cu(phen)][(As^VO₄)(V^V ₃O₇)(H₂O)] (1), [Cu(en)₂]₂[As₈V₁₄O₄₂(H₂O)]?·?2.5H₂O (2), [M(1,10-phen)₃]₂[As₈V₁₄O₄₂(H₂O)_0.5]?·?0.5H₂O (M?=?Mn, 3, Cd, 4) (1,10-phen?=?1,10-phenanthroline) have been hydrothermally synthesized for the first time and characterized by elemental analyses, XPS spectra, EPR spectra, IR spectra, TG analyses and single crystal X-ray diffraction. The structure of compound 1 consists of arsenic vanadate ribbons coordinated by the [Cu(phen)]²⁺ complex, while compounds 2 to 4 possess a spherical [As₈ ^IIIV₁₄ ^IVO₄₂]^4? cage with H₂O molecules encapsulated. The unexpected preparation 1 and the synthesis of compounds 2 to 4 on the basis of same polyoxoanion structures show that the pH value of the reaction plays a crucial role in controlling the basic architectures.     

Solvothermal synthesis and crystal structure of the Mo(VI)-bridged helical chain containing Mo2(V) dimers: (C4H12N2)2[(MoV2O4)(MoVIO4)(C2O4)2]·2H2O

A new molybdenum complex (C₄H₁₂N₂)₂[(Mo^V₂O₄)(Mo^VIO₄)(C₂O₄)₂]·2H₂O, was solvothermally synthesized and characterized by single-crystal X-ray diffraction. The structure of the compound consists of oxalate acid-coordinated mixed-valent [Mo^V₂O₄][Mo^VIO₄] helical chains and protonated piperazine cations. The helical chains are built up from the [Mo^V₂O₄] units and [Mo^VIO₄] tetrahedral. The central axis about helical chain is a 2-fold screw axis. The compound crystallizes in the space group P2₁/n of monoclinic system with a = 11.396(2) Å, b = 14.107(3) Å, c = 15.805(3) Å, β = 102.09(3)°, V = 2484.6(9) Å³, Z = 4. Other characterizations by elemental analysis, IR, and thermal analysis for this compound are also given.     

Assembly of two new polyoxometalate-templated supramolecular compounds by utilizing flexible 1,4-bis(pyrazol-1-ylmethyl)benzene ligand

Two new polyoxometalate-templated supramolecular compounds, [Cu^I₄(bpmb)₄][PMo^VI₁₁Mo^VO₄₀] (1) and [Cu^I₄(bpmb)₄SiW₁₂O₄₀] (2) (bpmb = 1,4-bis(pyrazol-1-ylmethyl)benzene), have been synthesized under hydrothermal conditions and characterized by routine methods. Structural analysis shows that in 1, there exist crown-like [Cu^I₄(bpmb)₄] coordination macrocycles, and the Keggin polyanions [PMo ^VI₁₁Mo^VO₄₀]^4? (abbr. as PMo₁₂), which direct the crown-like macrocycle to form a 3-D supramolecular framework. In 2, there exist unusual meso-helix chains, and these chains are mutually interlaced in a wave–trough pattern, but without intersection resulting in a multi-cavity layer, in which the [SiW₁₂O₄₀]^4? (abbr. as SiW₁₂) clusters as guest molecules occupy the cavities of the layers. The distinct structural features of the two compounds suggest that Keggin polyanions should play a significant role in the process of assembly. Electrocatalytic properties of 1 and 2 were investigated.     

Synthesis, structure and magnetism of a S-shaped multi-iron substituted arsenotungstate containing a trivacant Keggin [B-α-AsW9O34] and a hexavacant Keggin [α-AsW6O26] fragments

A S-shaped multi-iron substituted arsenotungstate [enH₂]₂[(α-H₂As^VW₆O₂₆)Fe₃(H₂O)(B-α-H₄As^VW₉O₃₄)]₂[Fe]₂·8H₂O (1) (en=ethylenediamine) has been prepared by reaction of K₁₄[As₂^IIIW₁₉O₆₇(H₂O)]·nH₂O with Fe₂(SO₄)₃·xH₂O under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, UV spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The skeleton of 1 consists of two asymmetric sandwich-type subunits [(α-H₂As^VW₆O₂₆)Fe₃(H₂O)(B-α-H₄As^VW₉O₃₄)]⁵⁻ linked by a di-Fe^III cluster. Moreover, magnetic susceptibility measurements demonstrate that 1 indicates the antiferromagnetic coupling interactions within Fe^III centers with the best-fitting set of parameters of J₁=−7.07 cm⁻¹, J₂=−0.45 cm⁻¹ and g=2.05, which are generated by the addition of the expressions of the molar susceptibilities of two tri-Fe^III clusters and one di-Fe^III cluster derived from for spin pairs coupled through the isotropic exchange interactions.     

Synthesis and photo-/electro-catalytic properties of a 3-D supramolecular framework based on [HxAs2Mo6O26](6−x)− and {Cu-diz} complexes

Herein, an arsenomolybdate, {Cu(diz)₄(H₂O)₂}[{Cu(diz)₂(H₂O)₂}₂{As₂Mo₆O₂₆}]·2H₂O (diz = 1,2-diazole) (1), has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR, TG, XPS, PXRD, and UV–Vis-NIR. The {Cu-diz} complexes link the [As₂Mo₆O₂₆]^6? polyoxoanions, forming a 1-D infinite chain. The 2-D layer is constructed from 1-D chains through hydrogen bonds. Adjacent layers and free {Cu(diz)₄(H₂O)₂} complexes are fused through hydrogen bonding to form a 3-D topological framework with symbol of {4¹⁴·6¹⁰·8⁴}{4}². Compound 1 exhibits luminescence at room temperature, excellent degradation activity for four different organic dyes (RhB, MB, MO, and AP) under UV irradiation. The photocatalytic mechanism of 1 is discussed in detail. Furthermore, the electrocatalytic activity of 1 toward hydrogen peroxide has also been studied.     

Two extended organic–inorganic hybrids based on sandwich tungstogermanates

Two inorganic–organic composite polyoxotungstates, [Cu(en)₂(H₂O)]₂[Cu(en)₂(H₂O)₂]-{[Cu(en)₂]₃[Cu₄(GeW₉O₃₄)₂]} · 10H₂O (1, en = ethylenediamine) and (H₂en){[Zn(en)₂]₄-[Zn₄(Hen)₂(GeW₉O₃₄)₂]} · 10H₂O (2), were hydrothermally synthesized and their structures determined by single-crystal X-ray diffraction. Compounds 1 and 2 consist of sandwich polyanions [Cu₄(B-α-GeW₉O₃₄)₂]^12? or [Zn₄(Hen)₂(GeW₉O₃₄)₂]^10? linked by [M(en)₂]²⁺ bridges to form 2-D networks, which are further packed into a 3-D supramolecular porous framework via extensive hydrogen bonding interactions. Their IR and UV spectra, thermal stabilities, and cyclic voltammograms were also investigated.