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Inspired by the metal‐oxo cluster structural feature and charge separation behaviour of the oxygen evolving center (OEC) in photosystem II (PS‐II) under photoirradiation, a new crystalline photochromic polyoxomolybdate, MV2[β‐Mo8O26] (1, MV=methyl viologen cation), is designed as a biomimetic oxygen evolution reaction (OER) catalyst in neutral electrolytes. After photoinduced electron transfer (PIET) with colour change from colourless to grey, it remains in an ultra‐stable charge‐separated state over a year under ambient conditions. The observed overpotential at 10 mA ⋅ cm−2 and Tafel slope decrease by 49 mV and 62.8 mV ⋅ dec−1 after coloration, respectively. The outstanding OER performance of the coloured state in neutral electrolytes even outperforms the commercial RuO2 benchmark. Experimental and theoretical studies show that oxygen holes within polyanions after irradiation serve as sites for enhancing direct O−O coupling, thus effectively promoting OER. This is the first successful application of electron‐transfer photochromism to realize OER activity gain. [ABSTRACT FROM AUTHOR]

Compounds with redox activities have appealing applications in catalytic, electronic and magnetic properties, but the redox inert of polyoxoniobates (PONbs) significantly limits their applications for a long time. In this work, we are able to integrate organophosphate and lanthanide cluster into PONb to create the first family of inorganic‐organic hybrid organophosphate‐Ln‐PONb composite clusters. These novel species not only present the first family of redox active PONbs that can be reduced to form long‐lived "heteropoly blues" under ambient conditions, but also a new photochromic system. More importantly, the analyses of the electronic configurations and photochromic properties for a series of designed proof‐of‐concept PONbs models allow us to discover a D‐f‐A electron transfer mechanism, that is, photoinduced electron is transferred from a photosensitive organophosphate electron donor (D) to the NbV electron acceptor (A) through the unoccupied 4 f‐orbitals of Ln (f). This work paves the way for developing diverse PONb‐based redox materials and expanding the possibility of the applications of PONbs in the redox chemistry. [ABSTRACT FROM AUTHOR]

Cup‐shaped molecules are of great interest due to their appealing architectures and properties. Compared with widely studied calixarenes, polyoxometalate‐based cup‐shaped molecules currently remain a virgin land waiting for exploration. In this work, we report the first discovery of two giant cup‐shaped inorganic–organic hybrid polyoxoniobates (PONbs) of {Cu12Nb120} and {Cd16Nb128}. The former integrates three tricyclic Nb24 clusters and a hexacyclic Nb48 cluster into a cup‐shaped molecule via a Cu12 metallacalixarene, while the latter unifies two tricyclic Nb24 clusters and a brand‐new pentacyclic Nb40 cluster into another cup‐shaped molecule via a hybrid Cd16 unit. With 132 and 144 metal centers, {Cu12Nb120} and {Cd16Nb128} show the largest two inorganic–organic hybrid PONbs known to date. [ABSTRACT FROM AUTHOR]

In this work, two rare high‐dimensional polyoxoniobates with formulas of H9[Cu(en)(H2O)2][Cu(en)2]8[Dy(H2O)4]3[Nb24‐O69(H2O)3]2 ⋅ 36H2O (1) and H9K[Cu(en)2(H2O)]5[Cu(en)2]4‐[Eu(H2O)4]3[Nb24O69(H2O)3]2 ⋅ 2en ⋅ 45H2O (2) have been obtained under hydrothermal conditions. These extended materials are constructed from lanthanide‐incorporated triangular‐prism‐like polyoxoniobate secondary building units (SBUs) {[Ln(H2O)4]3[Nb24O69(H2O)3]2} (Ln=Dy, Eu). 1 and 2 represent the first examples of high‐dimensional polyoxometalate materials based on such lanthanide‐incorporated triangular‐prism‐like polyoxoniobate SBUs. Furthermore, the proton conduction property and the luminescent emission of these materials were evaluated. [ABSTRACT FROM AUTHOR]

This work demonstrates that the use of high‐negative and high‐symmetry lacunary polyoxometalates (POMs) for the clustering of alkali metal ions is a feasible strategy not only for the formation of rare high‐nuclearity alkali‐metal clusters but also for the construction of new‐type all‐inorganic ionic porous materials. By the strategy, an unprecedented high‐nuclearity K‐H2O cluster {K42(H2O)60} with core–shell K6@K36 configuration is stabilized by 8 C3v‐symmetry trivacant POMs [GeW9O34]10−, forming a novel giant ionic alkali‐metal‐POM composite cluster {K42Ge8W72O272(H2O)60} with more than 100 metal centers. The incorporated 42‐nuclearity K‐H2O cluster {K42(H2O)60} exhibits the highest‐nuclearity alkali‐metal‐water cluster known to date in POM chemistry. Further, the giant {K42Ge8W72O272(H2O)60} clusters can be linked by another kind of alkali metal ions Na+ to generate a fascinating three‐dimensional all‐inorganic ionic porous framework with high chemical stability, proton conductivity, and water vapor adsorption. Giant ionic cluster: The utilization of highly negative polyoxometalates for the clustering of alkali metal cations has allowed the synthesis of a rare all‐inorganic ionic porous material built from novel giant ionic clusters {K42Ge8W72O272(H2O)60} (K42W72), which exhibits high proton conductivity. The K42W72 not only is among the largest ionic clusters but also contains unprecedented core–shell K6@K36‐H2O cage. [ABSTRACT FROM AUTHOR]

Abstract: Two di-cadmium-substituted vanadoarsenates, [Cd(enMe)3]2{α-[(enMe)2Cd2As8V12O40(0.5H2O)]}·5.5H2O (1, enMe=1,2-diaminopropane) and [Cd(enMe)2]2{β-[(enMe)2Cd2As8V12O40(0.5H2O)]} (2), were hydrothermally synthesized and characterized by elemental analyses, IR, TGA, UV–Vis, XRD, magnetic measurements and single crystal structural analyses. Crystal data for 1: monoclinic, P2(1)/c, a=15.040(9)Å, b=20.288(12)Å, c=27.873(17)Å, β=98.046(8)°, V=8421.3(19)Å3, Z=4; for 2: monoclinic, P2(1)/n, a=12.753(3)Å, b=19.334(5)Å, c=14.310(3)Å, β=99.984(3)°, V=3475.1(14)Å3, Z=2. X-ray diffraction analyses reveal that compounds 1 and 2 exhibit isolated and one-dimensional inorganic–organic hybrid structures, respectively. The former is the first di-cadmium-substituted vanadoarsenate derived from α-{As8V14O42} shell, while the latter is another kind of di-cadmium-substituted vanadoarsenate derived from β-{As8V14O42} shell. Variable temperature susceptibility measurements demonstrate the presence of antiferromagnetic interactions between VIV cations in 1 and 2. [Copyright &y& Elsevier]

Abstract: Combination of in-situ generated monocopperII-substituted Keggin polyoxoanions with copperII–organoamine complexes under hydrothermal conditions results in seven inorganic–organic composite polyoxotungstates [Cu(en)2(H2O)]2{[Cu(en)2][α-PCuW11O39Cl]}·3H2O (1), {[Cu(en)2(H2O)][Cu(en)2]2[α-PCuW11O39Cl]}·6H2O (2), {[Cu(en)2(H2O)]2[Cu(en)2][α-XCuW11O39]}·5H2O (3/4, X=SiIV/GeIV), {[Cu(deta)(H2O)2]2[Cu(deta)(H2O)][α-XCuW11O39]}·5H2O (5/6, X=GeIV/SiIV) and [Cu(dap)2]2{[Cu(dap)2]2[Cu(dap)2][α-PCuW11O39]2} (7) (en=ethylenediamine, dap=1,2-diaminopropane and deta=diethylenetriamine). 1 is an isolated structure whereas 2 is a 1-D chain structure, but both contain [α-PCuW11O39Cl]6− polyoxoanions. 3–6 contain the 1-D linear chains made up of [α-XCuW11O39]6− polyoxoanions in the pattern of –A–A–A– (A=[α-XCuW11O39]6−), while 7 demonstrates the first 1-D zigzag chain constructed from [α-PCuW11O39]2 10− polyoxoanions via [Cu(en)2]2+ bridges in the pattern of –A–B–A–B– (A=[α-PCuW11O39]2 10−, B=[Cu(en)2]2+). The successful syntheses of 1–7 can provide some experimental evidences that di-/tri-/hexa-vacant polyoxoanions can be transformed into mono-vacant Keggin polyoxoanions under hydrothermal conditions. [Copyright &y& Elsevier]

Abstract: Three novel hetero-polyoxovanadates, [Cd(2,2′-bpy)3]{[Cd(dien)]As8V14O42(H2O)} (1, 2,2′-bpy=2,2′-bipyridine, and dien=diethylenetriamine), [Zn(2,2′-bpy)2]2[As8V14O42(H2O)]·H2O (2) and [Ni(en)2]3[As8V14O42(HPO3)]·4H2O (3, en=ethlenediamine), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Crystal data: 1 monoclinic, P2(1)/n, , , , , Z=4. 2, orthorhombic, P2(1)2(1)2(1), , , , . 3, triclinic, , , , , , , , . Compounds 1–3 are all made of the {As8V14O42} shells linked by corresponding transition metal complexes into extended structures. Compound 1 and 2 present 1-D wave-like and tubular structures, respectively, while compound 3 exhibits a novel 2-D structure containing interwinding puckery layers. Variable temperature susceptibility measurements demonstrate the presence of antiferromagnetic interaction between VIV cations in 1 and 2. [Copyright &y& Elsevier]

Abstract: Two new arsenic–vanadium clusters, [Zn(2,2′-bpy)3]2[As8V14O42(H2O)]·4H2O (1, 2,2′-bpy =2,2′-bipyridine) and [Zn(2,2′-bpy)(dien)]2[As8V14O42(H2O)]·2H2O (2, dien=diethylenetriamine), have been hydrothermally synthesized and characterized by IR, elemental analysis, EPR, XRD, TGA, magnetic measurements, and single-crystal X-ray diffraction analysis. Crystal data: 1, triclinic,, a=14.3793(2)Å, b=16.7706(2)Å, c=24.7077(1)Å, α=93.740(1)°, β=93.182(1)°, γ=113.363(1)°, Z=2; 2 orthorhombic, P4(3)2(1)2, a=21.3442(7)Å, b=21.3442(7)Å, c=15.8837(7)Å, Z=4. X-ray crystallographic study showed that compound 1 is composed of the discrete [As8V14O42(H2O)]4- polyoxoanions and chiral [Zn(2,2′-bpy)3]2+ cations, while compound 2 is constructed from [As8V14O42(H2O)]4− cluster anions and novel [Zn(2,2′-bpy)(dien)]2+ complex fragments linked through hydrogen bonds into a network. Variable temperature susceptibility measurements demonstrate the presence of antiferromagnetic interaction between VIV cations in 1 and 2. [Copyright &y& Elsevier]

Abstract: A new arsenic–vanadium clusters, [NH2(CH2CH2)2NH2]3[As8V14O42(SO4)]·6.5H2O (1), have been hydrothermally synthesized and characterized by IR, elemental analysis, TGA, magnetic property, and single crystal X-ray diffraction analysis. Crystal data: Monoclinic, P2(1)/n, a=21.963(2)Å, b=14.508(1)Å, c=23.054(3)Å, β=118.316(3)°, Z=4. X-ray crystallographic study showed that crystal 1 is composed of the discrete cluster anions [As8V14O42(SO4)]6-, organic amine molecules providing charge-compensation, space-filling, and structure-directing roles, and lattice water molecules occupying in the structure. The study of the magnetic susceptibility of 1 demonstrates the presence of antiferromagnetic interaction between VIV cations in 1. [Copyright &y& Elsevier]

In this review, the recent advancements of POMOFs and POMOPs, including their assembly methodologies, classification and related applications are summarized. Moreover, the current challenges in the design and fabrication of POMOFs and POMOPs as well as the great potential in these two areas are also discussed. • The recent advancements of POMOFs and POMOPs are summarized. • The advantages of using POM clusters to construct POMOFs and POMOPs are summarized. • Synthetic strategies for further development of POMOFs and POMOPs are presented. • Understanding the structure-property relationships of POMOFs and POMOPs. • The current challenges and the great potential of POMOFs and POMOPs are discussed. During the past two decades, the search of strategies to introduce polyoxometalate (POM) clusters as secondary building units (SBUs) to construct porous extended POM-organic frameworks (POMOFs) and discrete POM-organic polyhedra (POMOPs) have attracted sustained interests because such materials not only integrate the advantages of both POMs and framework/polyhedra structures, but also exhibit good prospects in photo-/electro-catalysis, separation, molecular recognition, host-guest chemistry and so on. In this review, the recent advancements of POMOFs and POMOPs, including their assembly methodologies, classification and related applications are summarized. Moreover, the current challenges in the design and fabrication of POMOFs and POMOPs as well as the great potential in these two areas are also discussed. [ABSTRACT FROM AUTHOR]

• The recent advancements of all-inorganic POM cages, including their assembly methodologies, classification and related applications are summarized. • The advantages of using POM clusters as SBUs to construct all-inorganic POM cages are summarized. • Feasible synthetic strategies for further development of all-inorganic POM cages are presented. • Understanding the structure–property/application relationships of all-inorganic POM cages. • The current challenges in the design and fabrication of all-inorganic POM cages as well as the great potential in this area are discussed. Searching for suitable methods to construct all-inorganic cage materials by using polyoxometalates (POMs) as secondary building units (SBUs) has been of great interest, because such materials not only exhibit fascinating cage-shaped structures and unique physicochemical properties derived from both cage architectures and POM clusters, but also have promising and practical applications in areas of molecule separation, guest recognition, molecular reactors, photocatalysis, environmental protection, and so on. In this review, the recent development in all-inorganic POM-based cage materials is summarized, including their assembly methods, structures, properties, and related applications. Moreover, the current challenges in the design and assembly of all-inorganic POM cages as well as the development potential of this area also discussed. [ABSTRACT FROM AUTHOR]

An all-inorganic three-dimensional (3D) polyoxoniobate (PONb) framework, Na 6 K 4 [(Nb 6 O 19)CrIII(H 2 O) 2 ] 2 ·38H 2 O (1) has been synthesized via the hydrothermal method. The fundamental building unit of [(Nb 6 O 19)CrIII(H 2 O) 2 ] 2 10− is connected by K+ ions, forming a 3D framework structure with channels along the b -axis. Compound 1 exhibits good thermal stability, and selectively absorbs Co2+ ions while excluding Ni2+ ions from acetonitrile solutions, PXRD analysis confirms that its framework remains intact after adsorption, indicating its potential as an effective ion-exchange material. An all-inorganic three-dimensional chromium-incorporated polyoxoniobate framework has been synthesized. This framework possesses channels along the b -axis and exhibits good thermal stability. Ion exchange experiments indicate that this framework selectively absorbs Co2+ ions in acetonitrile, and maintains structural integrity after ion exchange progress. [Display omitted] • A new chromium-incorporated polyoxoniobate (PONb) was synthesized and characterized. • The compound represents a POM-based all-inorganic three-dimensional framework. • The compound exhibits good thermal/solvent stability. • This compound can selectively absorb Co2+ in organic solvents over Ni2+. • The framework remains intact after the ion-exchange process. • This work enriches the structural types of PONbs and ion-exchange materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The developments of POM-based macrocycles including their syntheses, structures, properties, and related applications are summarized. • The interesting modular hierarchical assembly of POM-based macrocycles was summarized. • The structure–property/application relationships of POM-based macrocycles are summarized. • The development prospects and the present challenges in the study of POM-based macrocycles are discussed. Polyoxometalate (POM) macrocycles have been extensively investigated due to their potential applications in various fields, including sensing, optics, magnetism, proton conduction, catalysis, and host–guest chemistry, leveraging the advantages offered by their unique wheeled structures. In this review, the recent progress of POM macrocycles, including their assembly strategies, crystal structures, properties, and various applications, is reviewed. Additionally, the current obstacles and challenges regarding the design and construction of POM macrocycles are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: A novel di-copperII-complex substituted monovacant Keggin polyoxotungstate [Cu(2,2′-bpy)(H2O)][H2PW11O39Cu2(2,2′-bpy)2(H2O)(OH)]·1.5H2O (1) (2,2′-bpy=2,2′-bipyridine) with a 1D polymeric chain has been hydrothermally synthesized and structurally characterized. To our knowledge, 1 is the rare magnetic di-transition metal-complex substituted monovacant Keggin polyoxotungstate with a unique 1D dual-bridging chain structure. Its magnetic behavior has been quantitatively analyzed by the Bleaney–Bowers equation, indicating the presence of weak antiferromagnetic interactions within dinuclear CuII centers. [Copyright &y& Elsevier]

[Display omitted] • The developments of POM-templated silver clusters are reviewed. • The syntheses, structures, properties and applications of POM-templated silver clusters are summarized. • The structure–property/application relationships of POM-templated silver clusters are discussed. • The development prospects and the current challenges for POM-templated silver clusters are discussed. • The suggestions for the further development of POM-templated silver clusters are presented. The search for feasible strategies to construct high-nuclear silver clusters has been attracting continuous interests because such materials not only exhibit aesthetic structures and fascinating properties, but also show promising applications in photoluminescence, antibiosis materials, photochromism, nano-materials, and electron transfer/communication materials. Anions are well-known as templates to direct the formation of silver clusters and control the shapes, sizes, and functions of the final products. As a unique class of anionic metal-oxo species, polyoxometalates (POMs) have been widely employed as templates in the syntheses of many intriguing silver clusters. In this review, the advances in POM-templated high-nuclear silver clusters in the past decade are summarized. Additionally, the different templating effects between POMs and simple inorganic anions are discussed. Actually, POMs can do much more than templates for the formation of diverse high-nuclear silver architectures, they also are significant in stabilizing the final products, functionalizing the composite clusters, and so on. Based on the current development in this area, the present challenges and perspectives for such materials are also presented. We hope that this review will be of reference value to accelerate the further development of silver clusters. [ABSTRACT FROM AUTHOR]

A novel guanidine-containing polyoxotantalate (POTa), H 12 [CN 3 H 6 ] 12 Na 2 (H 2 O) 6 [Cu(en) 2 (H 2 O)] 3 [Ta 6 O 19 ] 4 ·32H 2 O (1) has been synthesized by adding the CH 6 N 3 + as counter cations. The [Ta 6 O 19 ]8− clusters in compound 1 are connected by sodium ions to form a 2-D layered structure, which is further connected through [Cu(en) 2 (H 2 O)]2+ to form a 3-D supramolecular framework structure. Moreover, it is demonstrated that compound 1 exhibits reversible thermochromism behavior, changing from purple to dark blue upon heating and dehydration, which endows it with potential application in the field of anti-counterfeiting functional materials. Organic guanidine cations were first introduced as charge compensation ions to isolate a novel polyoxotantalate compound with 3-dimensional supramolecular framework structure and reversible thermochromism behavior upon heating and dehydration. [Display omitted] • A new inorganic-organic hybrid POTa was synthesized and characterized. • The compound exhibits an interesting 3-dimensional supramolecular framework structure with huge nanoscale channels. • Discrete POTa clusters and organic guanidine cations coexist to stabilize the 3-dimensional supramolecular framework. • The compound exhibits reversible thermochromism behavior upon heating and dehydration. • This work enriches the structural diversity of POTas and provides a new idea for new anti-counterfeiting materials. [ABSTRACT FROM AUTHOR]

Abstract: A novel polyoxotungstate cluster (H2en)2.5H9[Fe6Ge3W24O94(H2O)2]·14H2O (1) (en=ethylenediamine) has been hydrothermally synthesized and structurally characterized by IR, TGA and single-crystal X-ray diffraction. The polyoxoanion skeleton of 1 is composed of two tri-FeIII substituted B-α-(Fe3GeW9O40) Keggin units connected by an unique hexavacant GeW6O26 Keggin fragment, leading to the first Fe(III)-containing banana-shaped tungstogermanate. Magnetic measurements of 1 reveal that the exchange interactions within the trimetal clusters are antiferromagnetic. [Copyright &y& Elsevier]

[Display omitted] • The developments of all-inorganic POM-based frameworks including their syntheses, structures, properties and related applications are summarized. • The structure–property/application relationships of all-inorganic POM-based frameworks are summarized. • Feasible synthetic strategies for further development of all-inorganic POM-based frameworks are presented. • The development prospects and the current challenges for all-inorganic POM-based frameworks are discussed. Polyoxometalates (POMs) are an intriguing class of compounds that have been extensively studied due to their unique structures and diverse properties. In the past years, the synthesis of POM-based all-inorganic open frameworks has attracted increasing attention due to their potential applications in various fields, such as in electrode, magnetic, and catalytic materials. This review not only provides a comprehensive survey on POM-based all-inorganic open frameworks, including their structures, properties, and potential applications, but also discusses the current challenges in this field and provides an outlook for future research directions. [ABSTRACT FROM AUTHOR]

Two new inorganic-organic hybrid polyoxotantalates (POTas), H 2 [Co(en) 3 ] 3 Ta 6 O 19 (1) and Na 2 (H 2 O) 6 H 2 [Co(en) 3 ] 2 Ta 6 O 19 (2) (en ​= ​ethylenediamine) have been hydrothermally synthesized by using the phosphate buffer solution (Na 3 PO 4 /Na 2 HPO 4 , pH ​= ​12.36) as reaction medium. Notably, both compounds are built from anionic [Ta 6 O 19 ]8− clusters and [Co(en) 3 ]2+ complexes, showing good stability. Moreover, it is demonstrated that both compounds exhibit moderate proton conduction properties. Two new proton-conductive inorganic-organic hybrid polyoxotantalates (POTas), have been hydrothermally synthesized by using the phosphate buffer solution (Na 3 PO 4 /Na 2 HPO 4 , pH ​= ​12.36) as reaction medium, demonstrating a promising strategy for developing new functional POTa materials. [Display omitted] • Two new inorganic-organic hybrid POTas were synthesized and characterized. • Both compounds show good chemical stability under a wide range of pH values and in various organic solvents. • The phosphate buffer solution (Na 3 PO 4 /Na 2 HPO 4 , pH ​= ​12.36) was demonstrated to be a feasible reaction medium for new POTas. • The two compounds were proved to be potential proton conductive materials. • This work not only enriches the structural diversity of undeveloped POTa chemistry. [ABSTRACT FROM AUTHOR]

A series of novel 4s–4f heterometallic cluster substituted polyoxometalates (POMs) with formula of H 9 Na 12 K 2 [K 3 Ln 4 (NO 3) 2 (GeW 10 O 37) 2 (Ge 2 W 18 O 66)]·34H 2 O (1-Ln) (Ln = Dy, Ho, Er) have been hydrothermally made by adopting a trilacunary [A-α-GeW 9 O 34 ]10− as a precursor. 1-Ln represent the first examples of metal-substituted POM clusters based on mixed POM fragments including dilacunary [α-GeW 10 O 37 ]10− and multilacunary open Well-Dawson [Ge 2 W 18 O 66 ]16− fragments. • Novel 4s–4f heterometallic substituted POMs have been prepared and characterized. • The compounds contain mixed Keggin/ open Well-Dawson POM fragments. • The Luminescent properties of these compounds were systematically studied. • The work enriches the diversity of heterometallic metal cluster substituted POMs. • This work provides a new route for making new POMs based on mixed POM units. By adopting a trilacunary [A-α-GeW 9 O 34 ]10− as a precursor under hydrothermal conditions, a series of novel 4s–4f cluster substituted polyoxometalates (POMs) containing two types of in situ generated lacunary POM fragments have been made. These compounds were characterized by single-crystal X-ray diffractions, powder X-ray diffractions, infrared spectroscopy, thermogravimetric analyses, respectively. Structural analyses indicate that these compounds constructed from a seven-nuclearity K-O-Ln (Ln = Dy, Ho, Er) heterometallic cluster stabilized by mixed dilacunary Keggin [α-GeW 10 O 37 ]10−/multilacunary open Wells-Dawson [Ge 2 W 18 O 66 ]16− fragments. Furthermore, the solid luminescent properties of the compounds at room temperature were studied. [ABSTRACT FROM AUTHOR]