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Developing polyoxometalate‐cyclodextrin cluster‐organic supramolecular framework (POM‐CD‐COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM‐CD‐COSF crystalline structure produced through the self‐assembly process of a Krebs‐type POM, [Zn2(WO2)2(SbW9O33)2]10−, and two β‐CD units. The as‐prepared POM‐CD‐COSF‐based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm−2) to mitigate the polysulfide shuttle effect in lithium‐sulfur batteries. The designed Li−S batteries equipped with the POM‐CD‐COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of β‐CD, efficient polysulfide‐capture ability by the dynamic host–guest interaction of β‐CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li−S batteries. [ABSTRACT FROM AUTHOR]

Both polyoxometalates (POMs) and organic small molecular catalysts show excellent performance in chemical synthesis. The incorporation of nanoscale POMs and organocatalysts allows the full expression of their respective merits and enables elusive reactions to be achieved in one catalytic system. However, the covalent combination of such two components has been rarely explored. Here, we have successfully designed and synthesized a bifunctional nanomolecular catalyst L -Pro-Mn-Anderson by grafting L -proline onto an Mn-Anderson POM for the first time, and catalytic experiments show that L -Pro-Mn-Anderson can realize the one-pot alcohol oxidation/three-component reaction to synthesize two types of heterocyclic compounds (5-aryl-pyrimido[4,5-b]quinoline-dione derivatives and pyrazolo[3,4-b] pyridine derivatives) in high yields up to 97%. The detailed characterization of the catalyst and the catalytic mechanism has shown that L -Pro-Mn-Anderson exhibits synergistic effects that combine both organic and inorganic catalytic functions, and the covalent linkage improves the overall redox activity of the molecular catalyst. This study opens up a new way for the design and application of covalently combined organic–inorganic molecular catalysts toward de novo organic synthesis. [ABSTRACT FROM AUTHOR]

Anderson-type ([XM6O24]n−) polyoxometalates (POMs) are a class of polymetallic-oxygen cluster inorganic compounds with special structures and properties. They have been paid extensive attention by researchers now, due to their chemical modification and designability, which have been widely applied in the fields of materials, catalysis and medicine. In contemporary years, the application of Anderson-type POMs in catalytic organic oxidation reaction has gradually shown great significance for the research of green catalytic process. In this paper, we investigate the application of Anderson-type POMs in organic synthesis reaction, and these works are summarized according to the different structure of POMs. This will provide a new strategy for further investigation of the catalytic application of Anderson-type POMs and the study of green catalysis. [ABSTRACT FROM AUTHOR]

The advancement of a naturally rich and effective bifunctional substance for hydrogen and oxygen evolution reaction is crucial to enhance hydrogen fuel production efficiency via the electrolysis process. Herein, facile and scalable hydrothermal synthesis of bifunctional electrocatalyst of polyoxometalate anchored zinc cobalt sulfide nanowire on Ni‐foam (NF) for overall water splitting is reported for the first time. The electrochemical analysis of POM@ZnCoS/NF displays significantly low HER and OER overpotentials of 170/337 and 200/300 mV to attain a current density of 10/40 and 20/50 mA cm−2, respectively, demonstrating the notable performance of POM@ZnCoS/NF toward H2 and O2 evolution reaction in alkaline medium. Additionally, the electrolyzer consisting of the POM@ZnCoS/NF anode and cathode shows an appealing potential of 1.56 V to deliver 10 mA cm−2 current density for overall water splitting. The high electrocatalytic activity of the POM@ZnCoS/NF is attributed to modulation of the electronic and chemical properties, increment of the electroactive sites and electrochemically active surface area of the zinc cobalt sulfide nanowires due to the anchorage of polyoxometalate nanoparticles. These results demonstrate the advantage of the polyoxometalate incorporation strategy for the design of cost‐effective and highly competent bifunctional catalysts for complete water splitting. [ABSTRACT FROM AUTHOR]

One halide ion (X−) can bind on the surface of nanoscale Anderson‐type polyoxometalate (POMs) clusters [(n‐C4H9)4N]3{AlMo6O18(OH)3[(OCH2)3CCH3]}, and form stable complexes in solution with binding constant K=1.53×103. Single‐crystal structural analysis showed that this binding behavior occurs through multiple hydrogen bonding between X− and three hydroxy groups on the uncapped side of the cluster. This supramolecular interaction in the cluster systems means that their catalytic activities, evaluated from the oxidation of alcohols to aldehydes, can be switched upon the introduction of halide ions and water molecules. The halide ions work as inhibitors by blocking the active sites of the clusters while they can be re‐activated by the addition of water. [ABSTRACT FROM AUTHOR]

Engineering photoredox‐triggered chemical transformation via visible light has been an emerging area in organic synthesis. However, most of the well‐established photocatalysts are based upon either transition metal complexes involved with noble metals and organic ligands or photosensitive organic dyes, the development of pure inorganic molecular photocatalysts that could provide better stability and durability is greatly retarded. Herein we discover that the Anderson polyoxometalate (POM) Na4[NiMo6O18(OH)6] (1), which consists of pure inorganic framework built from a central NiII core supported by six MoVIO6 inorganic scaffold/ligands, can be used as a powerful photocatalyst. Upon irradiation with visible light (>400 nm), the compound can catalyze, in high efficiency, a wide range of reactions, including the oxidative cross‐coupling reaction of chlorides with amines, as well as oxidation of chlorides using molecular oxygen, affording various imines, aldehydes, and ketones, respectively in high selectivity and good yields. Owing to the robust inorganic framework, this catalyst exhibits excellent stability during the catalysis and reusability with little loss of the catalytic activity, thus providing an alternative without use of complicated organic ligands and expensive noble metal‐based photosensitizers. Best supporting role: A practical and efficient environmentally benign catalytic protocol of oxidation of cross‐coupling reaction of chlorides with amines, as well as oxidation of halides was developed with inorganic‐ligand supported Ni‐photocatalyst Na4[NiMo6O18(OH)6] using molecular oxygen and visible light. This method utilizes mainly an inorganic polymolybdate ligand to support the Ni2+ ion and 1 atm O2 gas as the sole oxidant, which can smoothly proceed to afford various imines and aldehydes or ketones with high yields and selectivity, avoiding the use of complicated organic ligands and expensive noble metal‐based photosensitizers. [ABSTRACT FROM AUTHOR]

Abstract: An efficient, durable, and low‐cost hydrogen evolution reaction (HER) catalyst is an essential requirement for practical hydrogen production. Herein, an effective approach to facilitate the HER kinetics of molybdenum carbide (Mo2C) electrocatalysts is presented by tuning its electronic structure through atomic engineering of nitrogen implantation. Starting from the organoimido‐derivatized polyoxometalate nanoclusters with inherent MoN bonds, the formation of N‐implanted Mo2C (N@Mo2C) nanocrystals with perfectly adjustable amounts of N atoms is demonstrated. The optimized N@Mo2C electrocatalyst exhibits remarkable HER performance and good stability over 20 h in both acid and basic electrolytes. Further density functional theory calculations show that engineering suitable nitrogen atoms into Mo2C can regulate its electronic structure well and decrease MoH strength, leading to a great enhancement of the HER activity. It could be believed that this ligand‐controlled atomic engineering strategy might influence the overall catalyst design strategy for engineering the activation sites of nonprecious metal catalysts for energy conversions. [ABSTRACT FROM AUTHOR]

Abstract: A series of rod‐shaped polyoxometalates (POMs) [Bu4N]7[Mo6O18NC(CH2O)3MnMo6O18(OCH2)3CNMo6O18] and [Bu4N]7[ArNMo6O17NC(CH2O)3MnMo6O18(OCH2)3CNMo6O17NAr] (Ar=2,6‐dimethylphenyl, naphthyl and 1‐methylnaphthyl) were chosen to study the effects of cation–π interaction on macroionic self‐assembly. Diffusion ordered spectroscopy (DOSY) and isothermal titration calorimetry (ITC) techniques show that the binding affinity between the POMs and Zn2+ ions is enhanced significantly after grafting aromatic groups onto the clusters, leading to the effective replacement of tetrabutylammonium counterions (TBAs) upon the addition of ZnCl2. The incorporation of aromatic groups results in the significant contribution of cation–π interaction to the self‐assembly, as confirmed by the opposite trend of assembly size vs. ionic strength when compared with those without aromatic groups. The small difference between two aromatic groups toward the Zn2+ ions is amplified after combining with the clusters, which consequently triggers the self‐recognition behavior between two highly similar macroanions. [ABSTRACT FROM AUTHOR]

Adipic acid is an important raw chemical for the commercial production of polyamides and polyesters. The traditional industrial adipic acid production utilizes nitric acid to oxidize KA oil (mixtures of cyclohexanone and cyclohexanol), leading to the emission of N2O and thus causing ozone depletion, global warming, and acid rain. Herein, we reported an organically functionalized β-isomer of Anderson polyoxometalates (POMs) nanocluster with single-atom Mn, β-{[H3NC(CH2O)3]2MnMo6O18}- (1), as a highly active catalyst to selectively catalyze the oxidation of cyclohexanone, cyclohexanol, or KA oil with atom economy use of 30% H2O2 for the eco-friendly synthesis of adipic acid. The catalyst has been characterized by single crystal and powder XRD, XPS, ESI-MS, FT-IR, and NMR. A cyclohexanone (cyclohexanol) conversion of >99.9% with an adipic acid selectivity of ~97.1% (~85.3%) could be achieved over catalyst 1 with high turnover frequency of 2427.5 h-1 (2132.5 h-1). It has been demonstrated that the existence of Mn3+ atom active site in catalyst 1 and the special butterfly-shaped topology of POMs both play vital roles in the enhancement of catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: The efficient evolution of hydrogen through electrocatalysis is considered a promising approach to the production of clean hydrogen fuel. Platinum (Pt)‐based materials are regarded as the most active hydrogen evolution reaction (HER) catalysts. However, the low abundance and high cost of Pt hinders the large‐scale application of these catalysts. Active, inexpensive, and earth‐abundant electrocatalysts to replace Pt‐based materials would be highly beneficial to the production of cost‐effective hydrogen energy. Herein, a novel organoimido‐derivatized heteropolyoxometalate, Mo4‐CNP, is designed as a precursor for electrocatalysts of the HER. It is demonstrated that the carbon, nitrogen, and phosphorus sources derived from the Mo4‐CNP molecules lead to in situ confined carburization, phosphorization, and chemical doping on an atomic scale, thus forming nitrogen‐doped porous molybdenum carbide and phosphide hybrids, which exhibit remarkable electrocatalytic activity for the HER. Such an organically functionalized polyoxometalate‐assisted strategy described here provides a new perspective for the development of highly active non‐noble metal electrocatalysts for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Several novel triol-ligands functionalized Anderson–Evans type polyoxotungstates, K3Na3[{HOCH2C(CH2O)3}AlO3W6O18], K3Na3[{HOCH2C(CH2O)3}CrO3W6O18], K3Na3[{HOCH2C(CH2O)3}CoO3W6O18], and K3Na3[{H3CC(CH2O)3}CoO3W6O18], were successfully synthesized and characterized, in which some of the central metal ions have never been found in the Anderson-type polyoxotungstates. The single crystal X-ray diffraction analysis indicated that the clusters were on a status, in which only one-side μ3-O was protonated. This indicates that the three-protonated cluster is a common type of Anderson cluster aside zero-protonated (A-type) and six-protonated (B-type), which could be named as the T-type. [ABSTRACT FROM AUTHOR]

A redox-responsive hybrid of polyoxometalate and conducting oligomer including its self-assemblies with controllable morphologies are reported. To this end, a hybrid molecule, containing a Lindqvist hexamolybdate as the polar head group and N,N′-bis(4′-amino-2,6-dimethylphenyl)-1,4-quinonediimine as the redox-responsive and aggregating group, is prepared. This hybrid exhibits redox-responsive behavior with controllable assembling morphological transition from spherical vesicles to short cylindrical vesicles. Besides, the hybrid-based self-assemblies are transferred to the surface, thus the surface wettability can be well-tuned owing to the morphological transitions of the self-assemblies. By marrying conducting materials with polyoxometalate chemistry, this research opens a new horizon of polyoxometalate-based self-assembled systems with potential applications in functional materials. [ABSTRACT FROM AUTHOR]

Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH4) n[MMo6O18(OH)6] (M=Cu2+; Fe3+; Co3+; Ni2+; Zn2+, n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six MoVI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis. [ABSTRACT FROM AUTHOR]

Three novel bis(Triol)-functionalized Anderson cluster derivatives (POM–L–POM, POM–L, L–POM–L) were efficiently synthesized, which manifest interesting self-assembly and synergistic effects. They provided strong support in synthons, applications in syntheses and properties for designing organic–inorganic hybrid chains. [ABSTRACT FROM AUTHOR]

The first example of a heterogeneous iron(III)-catalyzed aerobic oxidation of aldehydes in water was developed. This method utilizes 1 atmosphere of oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification. Its operational simplicity, gram-scale oxidation, and the ability to successively reuse the catalyst, make this new methodology environmentally benign and cost effective. The generality of this methodology gives it the potential to be used on an industrial scale. [ABSTRACT FROM AUTHOR]

The first example of a heterogeneous iron(III)-catalyzed aerobic oxidation of aldehydes in water was developed. This method utilizes 1 atmosphere of oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification. Its operational simplicity, gram-scale oxidation, and the ability to successively reuse the catalyst, make this new methodology environmentally benign and cost effective. The generality of this methodology gives it the potential to be used on an industrial scale. [ABSTRACT FROM AUTHOR]

The first molybdovanadate cluster with a polyarylimido trimetal fragment, [V4Mo3O14(NAr)3(μ2-NAr)3]2−, was in situ synthesized by using (TBA)3[H3V10O28] as proton and vanadium sources. Additional aniline hydrochlorides will give rise to the formation of phenyl guanidines, which will serve as cations and proton donors to form chain-like and dimeric supermolecules via H-bonding. [ABSTRACT FROM AUTHOR]

Herein we report a step-by-step strategy for the organic modification of polyoxovanadates, which is based on a suitable polyoxovanadate platform, and a series of novel functionalized polyoxovanadates can be synthesized conveniently by sequential esterification and amidation reactions. [ABSTRACT FROM AUTHOR]

By addition of excess acid into the reaction mixture, a series of organically-derived Anderson-type polyoxometalates, {[R1CR2(CH2O)2]CrMo6O18(OH)4}3−, with diols as the ligands are reported herein. Such a diol functionalization mode not only works for some specific triol ligands but also can readily be extended to the diol ligands, which will greatly enrich the species of alkoxo-derivatized Anderson POM clusters. [ABSTRACT FROM AUTHOR]

A hexamolybdate-based organic–inorganic hybrid molecule containing a chloralkane fragment is synthesized and its Cl atom can be substituted by iodine and nitrate through nucleophilic substitution reactions in high yields, which provide a post-functionalization protocol to bring in various additional functional groups into polyoxometalate-based hybrid materials under mild conditions. [ABSTRACT FROM AUTHOR]

A class of monoorganoimido-substituted hexamolybdates containing a pyridine group have been firstly synthesized. Furthermore, a reaction protocol of alkylation based on the resulting pyridine-functionalized hexamolybdates has been developed, with which a type of zwitterionic clusters has been successfully obtained. [ABSTRACT FROM AUTHOR]

The μ2-O atom in Anderson polyoxometalates was regioselectively activated by the introduction of protons, which, upon functionalization with triol ligands, could afford a series of unique χ isomers of the organically-derived Anderson cluster {[RCC(CH2O)3]MMo6O18(OH)3}3−. Herein proton-controlled isomer transformation between the δ and χ isomer was observed by using the fingerprint region in the IR spectra and 13C NMR spectra. [ABSTRACT FROM AUTHOR]

A series of aliphatic organoimido derivatives of hexamolybdate based on amantadine, namely (nBu4N)2-[Mo6O18(≡NC10H15)] (1), (nBu4N)2 {cis-[Mo6O17(≡NC10H15)2]} (2), (nBu4N)2{trans-[Mo6O17(≡NC10H15)2]} (3), and (nBu4N)2[Mo6O16- (≡NC10H15)3] (4), was synthesized in reasonable yield by dehydration with N,N'-dicyclohexylcarbodiimide (DCC). They were characterized by IR and UV/Vis spectroscopy, elemental analysis, ESI mass spectrometry, and single-crystal X-ray structure analysis. The spectral and structural similarities and differences between monosubstituted, cis-disubstituted, and transdisubstituted organoimido derivatives were elucidated and may provide guidance for related work on organoimido-functionalized Lindqvist-type polyoxometalates. In addition, trans-disubstituted and polysubstituted derivatives containing aliphatic organoimido ligands have not yet been reported, and the crystal structure of the trans isomer may lead us to a deeper understanding of disubstituted derivatives. Furthermore, proliferation and morphology of MCF-7 cells were studied with compound 1. The present results show that the DCC-dehydrating protocol could be an efficient approach to covalently graft bioactive ligands such as amantadine onto POMs and enhance their application in clinical cancer treatment. [ABSTRACT FROM AUTHOR]

An inorganic-organic hybrid surfactant with a hexavanadate cluster as the polar head group was designed and observed to assemble into micelle structures, which further spontaneously coagulate into a 1D anisotropic structure in aqueous solutions. Such a hierarchical self-assembly process is driven by the cooperation of varied noncovalent interactions, including hydrophobic, electrostatic, and hydrogen-bonding interactions. The hydrophobic interaction drives the quick formation of the micelle structure; electrostatic interactions involving counterions leads to the further coagulation of the micelles into larger assemblies. This process is similar to the crystallization process, but the specific counterions and the directional hydrogen bonding lead to the 1D growth of the final assemblies. Since most of the hexavanadates are exposed to the surface, the 1D assembly with nanoscale thickness is a highly efficient heterogeneous catalyst for the oxidation of organic sulfides with appreciable recyclability. [ABSTRACT FROM AUTHOR]

On the basis of the well-developed N, N′-dicyclohexylcarbodiimide (DCC) imidoylization strategy, the novel trans-dinitrosyl-substituted polyoxometalate (POM) (NBu4)4[Mo6O17(≡NO)2] was synthesized in moderate yield with high purity through a highly selective reaction route under mild reaction conditions. Its structure was elucidated by IR and UV/Vis spectroscopy, ESI-MS, and single-crystal X-ray diffraction studies. Furthermore, its ability to undergo controlled NO release was confirmed by ESI-MS, and a curve of the amount of NO released as a function of time within a simulated body fluid system was obtained by UV spectroscopy. The rate of NO release is controlled by changing the pH of the system. This is the first time that the decomposition of a POM has been used to produce therapeutic NO species. This study provides a new route to controlled-release technology for NO storage and targeted delivery. [ABSTRACT FROM AUTHOR]

Doubly modified: Polyoxometalates can incorporate a large number of differENt functionalities in a way that mixes the ligands in a one ‐ pot reaction. A class of mixed organoimido bifunctionalized hexamolybdates is presENted that involves two differENt moieties L1 and L2, namely, differing aromatic, aromatic and aliphatic, and aliphatic moieties. [ABSTRACT FROM AUTHOR]

The functionalization of polyoxometalates (POMs), especially with an amino group to yield organonitrogenous derivatives of POMs, is an efficient approach to the enrichment of their structures and the diversification of their properties for various applications. The mechanism for the formation of organonitrogenous-derivatized hexamolybdates was explored by investigating the monofunctionalization of the [Mo6O19]2− ion with methylamine using the density functional theory (DFT) method. The calculations show that the direct imidoylization of hexamolybdate with methylamine is both kinetically and thermodynamically unfavorable. However, this imidoylization was found to take place readily in the presence of dimethylcarbodiimide (DMC), for which the free-energy barrier was calculated to be +32.5 kcal mol−1 in acetonitrile. Moreover, various factors controlling the efficiency of the imidoylization were examined. The calculations show that [W5MoO19]2− has a relatively lower reactivity than [Mo6O19]2−, and that the imidoylization of [W6O19]2− is an unfavorable process. With respect to the effect of carbodiimides, it is found that the catalytic activity is directly proportional to the electron-withdrawing effects of the substituents. As to the reactivity of RNH2, the computation results indicate that the free-energy barriers of the substitution reactions are linearly correlated with the basicity constants (p Kb) of the amino groups. It is noteworthy that the introduction of the proton dramatically decreases the free-energy barrier of the imidoylization of [Mo6O19]2− catalyzed by DMC to 24.3 kcal mol−1 in acetonitrile. [ABSTRACT FROM AUTHOR]

Abstract: Three monofunctionalized organoimido derivatives of [Mo6O19]2− bearing an electron-withdrawing chloro group (R= p-ClC6H4 1, m-ClC6H4 2, or o-ClC6H4 3) have been prepared in high purity and moderate to good yields using an easy reaction route of [α-Mo8O26]4− with corresponding aromatic amine hydrochlorides or a mixture of aromatic amines and their hydrochloride salts in the presence of N,N′-dicyclohexylcarbodiimide (DCC). These complexes have been characterized by 1H NMR, IR, UV–Vis, UV–Vis-NIR reflectance spectroscopy, cyclic voltammetry, and their semiconductive and redox properties were explored by these techniques. Their electronic absorption spectra were also interpreted based on first-principles electronic structure calculations and these features of the simulated spectra are qualitatively consistent with the observed UV spectra. Additionally, the composition and structure of compounds 1 and 2 were further confirmed by X-ray single-crystal diffraction studies. [Copyright &y& Elsevier]

Cover Feature: Unprecedented Halide-Ion Binding and Catalytic Activity of Nanoscale Anionic Metal Oxide Clusters (ChemPlusChem 11/2019) B The cover feature b shows that halide ions can bind on the surface of nanoscale, anionic metal oxide clusters and form stable complexes in solution. Anion binding, heterogeneous catalysis, clusters, hydrogen bonding, polyoxometalates. [Extracted from the article]

Formamides represent an abundant class of compounds in organic synthesis. They can be made efficiently by the direct catalytic coupling of methanol with amines in the presence of metal-based catalysts. However, these catalysts require complicated organic ligands, susceptible to oxidative self-degradation, restricting their practical applications. Here, we describe an inorganic ligand-supported chromium (III) catalyst, (NH4)3[CrMo6O18(OH)6], which consists of a central chromium (III) single-atomic core supported by a cycle-shaped inorganic ligand consisting of six MoVIO6 octahedra, shows excellent activity and selectivity. Various primary amines and secondary amines are successfully transformed into the corresponding formamides under mild conditions, and the formylation of primary diamines is also achieved. The chromium catalyst can be reused several times with little loss of the activity. Mechanistic insight is provided based on the observation of an intermediate and control experiments. Several catalytic methods for N-formylation of amines using noble metals or manganese pincer complexes are known. Here an air-stable and reusable chromium-based polyoxometalate is shown to catalyze the N-formylation of amines and diamines using methanol and hydrogen peroxide. [ABSTRACT FROM AUTHOR]

The synthesis of a new organic-inorganic nano-hybrid material [H 5 O 2 ][pip] 2.5 [SiMoV 2 W 9 O 40 ]. 7H 2 O (pip = Piperazine) (1) , in which piperazine is connected to a mixed-addenda Keggin structure of polyoxometalate by hydrogen bonding interaction, is reported. This nano-hybrid is characterized by single-crystal X-ray diffraction, fourier transform infrared (FT-IR), proton nuclear magnetic resonance ( 1 H NMR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), field emission scanning electron microscopy (FESEM) and cyclic voltammetry (CV). Single crystal X-ray analysis reveals that compound 1 has been assembled by hydrogen bonding among polyoxometalate, piperazine and crystallization water units. In this compound, polyoxometalates are located in the cavities which are created by piperazine groups in the zigzag form. In addition, based on XRD and FESEM analyzes, the nano composition of compound 1 can be verified. Moreover, the electrochemical properties of 1 were perused, which represent that 1 has an appropriate electrocatalytic activity towards reduction of nitrate (NO 2 − ) ion attributed to the metal-center and piperazine units. [ABSTRACT FROM AUTHOR]

An inorganic–organic hybrid surfactant with a hexavanadate cluster as the polar head group underwent stepwise assembly into micelles and finally, a 1D nanobelt structure with the cooperation of hydrophobic, electrostatic, and hydrogen‐bonding interactions; these last interactions are directional and lead to the anisotropic assemblies. The nanobelts are highly efficient heterogeneous catalysts for the oxidation of organic sulfides because most of the hexavanadates are exposed to the surface, showing its potential application in the petroleum industry and in environmentally benign chemistry. For more details see the Full Paper by T. Li, Y. Wei, T. Liu et al. on page 9589 ff. [ABSTRACT FROM AUTHOR]

[Display omitted] • POM-ZnFe 2 O 4 hybrid is reported first time for overall water splitting. • POM-ZnFe 2 O 4 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Electrocatalysts play an important role to increase the energy conversion efficiency of electrolysis processes. In this study, a heterostructure of zinc iron oxide (ZnFe 2 O 4) and polyoxometalate (POM) nanoplates (POM–ZnFe 2 O 4) was fabricated for the first time by a hydrothermal process. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) analysis of POM–ZnFe 2 O 4 furnished low overpotentials of 268 and 356 mV, and 220 and 290 mV to achieve current densities of 20 and 50 mA cm−2, respectively. In addition, an electrolytic cell composed of a POM–ZnFe 2 O 4 cathode and anode required an operating voltage of 1.53 V to deliver a current of 10 mA cm−2. The improved electrochemical performance of POM–ZnFe 2 O 4 compared to commercial and recently reported catalysts is attributed to the high electrocatalytically active surface area, modulation in the electronic and chemical properties and the formation of heterojunction of ZnFe 2 O 4 and POM, which are vital for accelerating HER and OER activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 3D nano-assembly of NiCo 2 S 4 /PANI@PW 12 /rGO hybrid is reported first time. • NiCo 2 S 4 /PANI@PW 12 /rGO hybrid delivers extraordinary performance for LIB and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Engineering hierarchical nanostructures with enhanced charge storage capacity and electrochemical activity are vital for the advancement of energy devices. Herein, a highly ordered mesoporous three-dimensional (3D) nano-assembly of Nickel Cobalt Sulphide/Polyaniline @Polyoxometalate/Reduced Graphene Oxide (NiCo 2 S 4 /PANI@POM/rGO) is prepared first time via a simple route of oxidative polymerization followed by a hydrothermal method. Morphological analysis of the resulting hybrid reveals the sheet-like structures containing a homogeneous assembly of PANI@POM and NiCo 2 S 4 on the graphene exterior maintaining huge structural integrity, large surface area and electrochemically active centres. The electrochemical analysis of the nanohybrid as the anode of the lithium-ion battery (LIB) has delivered ultra-huge reversible capacity of 735.5 mA h g−1 (0.1 A g−1 after 200 cycles), superb capacity retention (0.161% decay/per cycle at 0.5 A g−1 for 1000 cycles), and significant rate capability (355.6 mA h g−1 at 2 A g−1). The hydrogen evolution reaction (HER) measurement also proves remarkable activity, extremely low overpotential and high durability. The extraordinary performance of the nanohybrid is due to the presence of abundant electroactive centres, high surface area and a large number of ion exchange channels. These outstanding results prove the advantages of a combination of NiCo 2 S 4 , graphene sheets, and PANI@POM in energy devices. [ABSTRACT FROM AUTHOR]

Abstract: The hexamolybdate cluster has been functionalized with fluorine-containing aromatic amine by the DCC (N,N′-dicyclohexylcarbodiimide) dehydrating protocol and two novel mono-functionalized arylimido derivatives of hexamolybdates bearing the electron-withdrawing trifluoromethyl group and trifluoromethoxy group, (Bu4N)2[Mo6O18(≡NAr)] (Ar= o-CF3C6H4) 1 and (Bu4N)2[Mo6O18(≡NAr)] (Ar= p-OCF3C6H4) 2 have been synthesized by improved method. Complete assignments were achieved for the title compounds by elemental analysis, IR, 1H NMR, UV/visible and single-crystal X-ray diffraction analyses. The preliminary herbicidal activity test indicated that they have some herbicidal activities. [Copyright &y& Elsevier]

Abstract: Two lanthanide-decorated polyoxometalates K[Ln2(α-SiW11O39)(H2O)11] (Ln=La, Ce) have been successfully synthesized and characterized with single-crystal X-ray diffraction, IR spectroscopy and thermogravimetric analysis. The two compounds have analogy structures, which consist of one-dimensional chains based on [α-SiW11O39]8− building blocks. The chains are further connected to a two-dimensional layer by potassium ions. The magnetic studies of compound 1 demonstrate a ferromagnetic interaction in 1. [Copyright &y& Elsevier]

Abstract: A novel polyoxometalate-based organic–inorganic hybrid compound, [Co(bpy)3]2 [Mo6O19] [β-(H2Mo8O26)]·4H2O (1), have been hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR and X-ray photoelectron spectra. Compound 1 represents the first example that racemic complexes coexisting with two kinds of polyoxomolybdate anions in the same crystal architecture, which should be of rare chance that four kinds of complexes crystallizes into a compound. [Copyright &y& Elsevier]

Abstract: A bicapped Keggin anion-supported cobalt–phenanthroline complex (1) has been hydrothermally synthesized and structurally characterized by elemental analyses, single crystal X-ray diffraction and IR spectrum. Interestingly, all the polyanions constitute an anionic layer, while all the polycations are linked to form a cationic layer by the hydrogen bonding interactions. The result of magnetic measurement for compound 1 shows a typical antiferromagnetic interactions in the 2–300K temperature range. [Copyright &y& Elsevier]

A novel bifunctionalized arylimido derivative of hexamolybdate, (Bu4N)2[Mo6O17(&z.tbnd6;NAr)2]2− (Ar=o-CH3C6H4) 1, in which the two o-tolylimido groups are bounded to hexamolybdate at the cis positions, was synthesized by self-assembled metathesis of α-type octamolybdate ion and o-toluidine with DCC as a dehydration agent. The most interesting characteristic of 1 is that the cluster anions form dimers via the π–π stacking between one of its two phenyl rings, and four such dimers are linked in turn via C–H⋯O hydrogen bonding involving terminal hexamolybdate oxygen atoms into ring-like tetramers in the solid state. [Copyright &y& Elsevier]

Abstract: A new monofunctionized arylimido derivative of hexamolybdate, (Bu4N)2[Mo6O18NC6H4N(CH3)2−p], is synthesized by α-octamolybdate and hydrochloride salt of N,N-dimethyl-1,4-dianiline with DCC as a dehydrating agent. The derivative’s crystal data has been obtained and the IR, UV–Vis, 1H NMR spectra and cyclic voltammetry properties have also been studied. [Copyright &y& Elsevier]

The design of a low-cost, highly efficient and durable electrocatalyst is very important to accelerate the energy conversion efficiency of the electrochemical process. Herein, a simple hydrothermal synthesis of the heterostructure of Wells-Dawson polyoxometalate and zinc iron layered double hydroxide nanosheet is presented for the first time on Ni-foam (ZnFe LDH-P 2 Mo 18 /NF). The electrocatalytic activity of ZnFe LDH-P 2 Mo 18 /NF shows significantly low overpotentials of 275, 330 mV and 273, 367 mV for OER and HER to acquire a current density of 20, 50 mA cm−2 respectively. Additionally, the electrolyzer composed of ZnFe LDH-P 2 Mo 18 /NF cathode and anode shows an attractive voltage of 1.54 V to carry 10 mA cm−2. The better electrochemical performance of the ZnFe LDH-P 2 Mo 18 /NF is ascribed to the variation of electronic and chemical features, growth of electrochemically active surface area/sites because of the construction of heterointerface of Wells-Dawson polyoxometalate and zinc iron LDH. These results further demonstrate the benefits of heterointerface engineering for efficient electrolysis. This study presents a novel hybrid of zinc-iron layered double hydroxide and Dawson polyoxometallate (ZnFe LDH-P 2 Mo 18 /NF) for electrocatalytic water splitting. Notably, ZnFe LDH-P 2 Mo 18 /NF reveals excellent electrocatalytic performance with a large number of electroactive sites, extremely low overpotential, and high durability throughout the water splitting process. [Display omitted] • ZnFe LDH-P 2 Mo 18 hybrid is reported first time for overall water splitting. • ZnFe LDH-P 2 Mo 18 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. [ABSTRACT FROM AUTHOR]

Highlights • Cu dendrites exclusively induced by Anderson type POM (NH 4) 4 [H 6 NiMo 6 O 24 ]. • Chemical association between POMs and Cu NPs was evidenced via XPS and Raman investigation. • Enhanced HER activity with NiMo 6 O 24 @Cu/TNA was achieved. • Mechanism of NiMo 6 O 24 @Cu/TNA electrochemical HER was investigated by Tafel study. • NiMo 6 O 24 @Cu/TNA system shows high stability with enhanced corrosion resistance under neutral and acidic environment. Abstract The design and synthesis of specific functional complex materials as desired catalysts for improved energy conversion and storage are of great importance and with grand challenges. Here, a facile synthesis strategy of Anderson POMs supported Cu dendrites toward electrochemical hydrogen evolution reaction with dramatically decreased overpotential under acidic aqueous condition is established in this work. We present the preparation of well crystallized Cu dendrites through co-electrodeposition on TiO 2 array with Anderson-type POM NiMo 6 O 24. Structural and state of valence investigation of the as-obtained electrocatalyst (NiMo 6 O 24 @Cu/TNA) evidence the specific morphology tunability and modification of Cu dendrites surfaces. During HER course, NiMo 6 O 24 can improve the H+ transfer and further help the H atom absorption which remedies the weakness of insufficient H atom absorption ability of Cu along with its strong electron transfer lowering overpotential upon HER. Therefore, HER with NiMo 6 O 24 @Cu/TNA is considerably enhanced by decreasing related overpotential of 130 mV compared to porous Cu foam. The modification of NiMo 6 O 24 endowed catalysts strong corrosion resistance assuring long term stability. Hence, the proposed strategy possesses improved activity and long term stability upon HER with NiMo 6 O 24 @Cu/TNA as electrocatalyst. Depending on the diversity of POMs, the current feasible and reliable heterogeneous electrocatalysts design with POMs would inspire more effective, low-cost strategies for energy conversion and open the pathway for large scale production. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Current trends in the alkoxylation chemistry of polyoxometalates. • Challenge: the controllable alkoxylation of polyoxometalates. • Synthetic strategies and structures of alkoxylated polyoxometalates are summarized. • Applications and future perspectives are reviewed. Abstract Polyoxometalates (POMs), an exceptional family of coordination clusters consisting of Mo, W, V, etc. early transition metal ions in their highest oxidation states, have received significant attention over recent years due to their structural versatility and unique and diverse chemical and physical properties. The functionalization of POMs with organic ligands provides a novel strategy to precisely incorporate POMs with advanced functional organic moieties on their surfaces and enhance their compatibility in organic media. Among the various organically functionalized synthetic strategies for POM-based organic–inorganic hybrid materials, alkoxylation of POMs stands for one of the hottest topics during the past decades, since the diverse and tunable alkoxyl ligands are able to anchor on the surface of many POMs clusters, forming novel and flexible organically functionalized POM clusters, which can be further exploited as building blocks to design various functionalized POM-based hybrids with charming catalytic properties, and biomedicine, energy, or functional materials applications. In this review, recent advances in alkoxylation chemistry of POMs from synthetic strategies, structural overviews to their functional applications have been discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recent development of polyoxometalates for hydrogen evolution reaction is summarized. • Mechanisms and challenges of polyoxometalates for hydrogen evolution reaction is summarized. • Structural design, performances and functions of polyoxometalates for HER electrocatalysis is summarized. • Perspectives for future design of highly efficient and stable HER electrocatalysts are proposed. Electrocatalytic water splitting via hydrogen evolution reaction (HER) from renewable energy sources is an attractive alternative to produce hydrogen, but it still encounters the limitations of large-scale applicability of Pt-based electrocatalysts. Therefore, abundant efforts have been devoted to design and fabricate highly efficient and stable noble-metal-free electrocatalysts to replace the expensive Pt-based electrocatalysts. Recently, polyoxometalates (POMs) and their derivatives have been proven to provide plentiful opportunities for designing and fabricating highly efficient and stable noble-metal-free HER electrocatalysts with controllable catalytic active sites and well-defined nanostructures. In this review, recent advances on coordination structures and HER performances of POMs-contained composites and POMs-derived transition metal carbides, chalcogenides, phosphides, nitrides and other electrocatalysts have been discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The in-situ confined carbonization of PMo 12 @UiO-66 reduces aggregation and improves conductivity of MoC@PC. • Etching ZrO 2 realizes desired porous MoC@PC with ultra-high specific surface area of 1039 m2·g−1. • Confined phosphorization of MoC@PC gives raise to superhydrophilic MoP-QDs@PC. • The superhydrophilic MoP-QDs@PC exhibits excellent HER performance superior to commercial 20% Pt/C. Fabricating low-cost, earth-enriched and high-performance electrocatalysts for hydrogen evolution reaction (HER) is significant but challenging for the development of a sustainable hydrogen economy. Herein, we report superhydrophilic molybdenum phosphide quantum dots on porous carbon matrix (MoP-QDs@PC) using polyoxometalates (POMs)-contained metal organic frameworks (MOFs) as precursors, where Keggin-type PMo 12 POMs clusters are confined within the zirconium-based UiO-66 MOFs (denoted as PMo 12 @UiO-66). We demonstrate that the as-formed MoC species by in-situ confined carbonization of PMo 12 @UiO-66 can be converted into superhydrophilic MoP-QDs by further phosphorization, while the porous carbon matrix can be converted into rich P and O co-doped carbon matrix, which greatly increase the wettability and the amount of catalytic active sites exposed to the electrolytes. The as-prepared MoP-QDs@PC electrocatalyst exhibits excellent HER performance, which outperforms commercial 20% Pt/C electrocatalyst when overpotential (η) higher than 197 mV and 233 mV under alkaline and acidic conditions, respectively. Depending on the diversity of POMs and MOFs, the current feasible and reliable MoP-QDs@PC electrocatalysts from PMo 12 @UiO-66 precursor would inspire more effective strategies to economical, efficient and stable electrocatalysts for hydrogen evolution. [ABSTRACT FROM AUTHOR]

A 1:1 complex of Lanthanide-substituted Lindqvist-type oxo-nitrosyl polymolybdate [NBu 4 ][La(CH 3 OH) 2 (DCU)NO 3 {Mo 5 O 13 (OMe) 4 (NO)}]·CH 3 OH ( 1 ) has been successfully synthesized by a one-pot self-assembly process of hydroxylamine hydrochloride with octamolybdate, DCC and La(NO 3 ) 3 in methanol under mild reaction conditions. The structure is determined by X-ray crystallography. It is notable that the compound is a Lindqvist-type POM with a capped lanthanum ion which is nine coordinated in a distorted square antiprism geometry. Interestingly, NO 3 − as the precursor, as well as the hydrated product DCU of DCC, are both coordinated with Lanthanum ion. The structure has also been characterized by IR, UV–vis and photoluminescence analysis. Photoluminescence analysis reveals that compound 1 emits weak green light in CH 3 CN, with the maximum emission at 530 nm. [ABSTRACT FROM AUTHOR]

Abstract: Two new compounds were obtained by modifying hexavanadate cores with pentaerythritol in aqueous solution, however, re-crystallized in water and acetonitrile, respectively. The molecular structures for (Bu4N)2[V6O13{(OCH2)3CCH2OH}2·H2O] (1) and (Bu4N)2[V6O13{(OCH2)3CCH2OH}2·4CH3CN] (2) (Bu, n-butyl) have been characterized by FT-IR, UV–Vis, and single crystal X-ray diffraction. Compound 1 and 2 crystallize in monoclinic and triclinic space groups, respectively. Compound 1 shows supramolecular chirality in two-dimensional molecular assemblies while 2 does not have such chiral structure. The role of solvent molecules to the formation of supramolecular chirality in self-assembly architectures of polyoxometalates-based hybrid materials is discussed based on these two crystal structures. [Copyright &y& Elsevier]

Abstract: Two organic–inorganic hybrid compounds, (Bu4N)2[Mo6O18(NAr)] (Ar= 2-CH3-4-BrC6H3 (1) or 2,6-CH3-4-BrC6H2 (2)) have been synthesized via the DCC dehydrating protocol of the reaction of [α-Mo8O26]4− with 2-methyl-4-bromoaniline hydrochloride or 2,6-dimethyl-4-bromoaniline hydrochloride in anhydrous acetonitrile, which have been characterized by UV–Vis spectra, 1H NMR, IR, cyclic voltammetry and X-ray single-crystal diffraction study. Both compounds crystallize in the monoclinic space group , which are featured in a terminal phenylimido group linked to a Mo atom of a hexamolybdate cluster by a Mo–N triple bond. Interestingly, there are two conformational isomers of the cluster anions of 1 and 2 in the crystals. By cyclic voltammetry study, their special redox properties were also found in the end. [Copyright &y& Elsevier]