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Exploring a novel photocatalyst for catalytic oxidation of toluene is a sustainable strategy for energy conversion in times of an energy crisis. However, designing an effective photocatalyst for the conversion of toluene remains challenging. Herein, a novel organic monophosphonate-modified high nucleus Cu-incorporated polyoxotungstate, K8H33[{Cu0.5(H2O)4}{Cu2(O3PCH2COO)(1,4,9-α-P2W15O56)}]4·Cl·60H2O (1), has been intentionally synthesized by a self-assembly process utilizing conventional aqueous method. It reveals that 1contains a polyanion of [{Cu0.5(H2O)}4{Cu2(O3PCH2COO)(1,4,9-α-P2W15O56)}]440–composed of four Dawson-type {1,4,9-α-P2W15} subunits, forming an oval-shaped structure and further connecting into a three-dimensional (3D) framework by lateral {Cu(H2O)4}2+. Interestingly, the trivacant {1,4,9-α-P2W15} subunits were observed in the organophosphonate acid-functionalized polyoxometalates for the first time. Notably, 1exhibits a wonderful performance in catalytic oxidation of the recalcitrant C(sp3)–H bond of toluene to benzoic acid with a conversion as high as 97% under visible light utilizing O2as an oxidant.

Three unique dl-malic acid covalently modified tetra-Ln3+-implanted tellurotungstates [H2(CH3)2]9NaH9[Ln4(H2O)14W6O13(OH)5(Mal)2(B-α-TeW9O33)4]·48H2O [Ln = La3+(1), Ce3+(2), Pr3+(3); H3Mal = dl-malic acid] were fabricated by reacting Na2TeO3, Na2WO4·2H2O, Mal, and LnCl3·6H2O with dimethylamine hydrochloride in an aqueous solution. The most prominent architectural feature of these compounds is the covalent connection mode of an organic ligand and a polyoxometallate backbone, which is relatively rare in the realm of polyoxotungstates. The tetrameric polyanion can be deemed as four [TeW9O33]8–fragments fused together via an intriguing hexanuclearity [W6O13(OH)5(Mal)2Ln4(H2O)14]13+cluster. Impedance measurements manifest that all three complexes display splendid proton conduction properties, with an exceptional conductivity for 2up to 2.48 × 10–2S·cm–1under 85 °C and 95% relative humidity. Moreover, compounds 1and 3exhibited fast reversible photochromic properties with allochroic half-life periods t1/2of 1.046 and 0.544 min, respectively.

The synthesis of visible light-responsive and efficient photocatalysts toward green Baeyer–Villiger oxidation organic synthesis is of extraordinary significance. In this work, we have synthesized two examples of visible light responsive crystalline polyoxometalate@metal–organic framework materials Ru-NiMoand Ru-CoMoby introducing Ru metalloligands and {CdM3O12} bimetallic units (M = Ni or Co). This is the first report of metalloligand-modified polyoxometalate@metal–organic framework materials with bimetallic nodes, and the materials form a three-dimensional framework directly through coordination bonds between {CdM3O12} bimetallic units and metalloligands. In particular, Ru-NiMocan achieve efficient photocatalytic conversion of cyclohexanone to ε-caprolactone in yields as high as 95.5% under visible light excitation in the range of λ > 400 nm, achieving a turnover number and turnover frequency of 955 and 440 h–1, respectively, which are the best known photocatalysts for Baeyer–Villiger oxidation, while apparent quantum yield measured at 485 nm is 4.4%. Moreover, Ru-NiMoexhibited excellent structural stability and recyclability, producing a 90.8% yield after five cycles of recycling.

The oil and gas industry frequently uses liquid corrosion inhibitors to reduce equipment and pipeline corrosion. However, this approach requires frequent additions, which are costly in terms of labor and materials. Solid corrosion inhibitor capsules (SCICs) have become an optimal alternative, as they provide long-term corrosion protection. However, the current encapsulation materials need to be modified for improving encapsulation capability. In this study, lauryl acrylate (LA) was grafted onto Ethylene-vinyl-acetates (EVA) to reduce its crystallinity and increase the interface force between EVA and oleic imidazoline (OIM). OIM was then encapsulated using the grafted EVA (EVA-g-LA) to form matrix-type solid capsules that possess the high encapsulation efficiency and long service life. The analysis with a UV–Vis spectrophotometer revealed that OIM had a stable release process from the SCIC matrix. Over a period of 91 days, the released OIM still had a high corrosion inhibition efficiency towards N80 steel (>80%). Using the prepared SCIC can reduce annual anticorrosion costs in oil and gas fields by 70%.

With the excellent properties of POM in the field of proton conductivity, the preparation of POM-based proton-conductive materials has burst into life. Herein, an unprecedented Sb-templated all-inorganic trimer Na8H18.64[(SbW14O52)3(Sb2W6.12Ru5.88O18)]·85H2O (1), which is based on tetravacant Dawson-like [SbW14O52]17–blocks and exhibits a trefoil type with D3symmetry, has been successfully designed and synthesized by the assembly of simple materials with a one-pot hydrothermal method under acidic conditions. Also, compound 1is systematically characterized by single-crystal X-ray diffraction, PXRD, ESI-MS, IR spectroscopy, UV–vis, elemental analysis, and TGA. Crystal structure data analysis demonstrates that compound 1is constructed by a hexagonal prismatic heterometallic {Sb2W6.12Ru5.88O18} core and three equivalent {SbW14} units bridged through μ2-O atoms in periphery. Subsequently, further property experiments show that compound 1exhibits high proton conductivity with a conductivity value (σ) of 3.07 × 10–2S cm–1at 75 °C and 80% relative humidity (RH). The activation energy of compound 1evaluated by the Arrhenius plots is 0.22 eV, which indicates that the Grotthuss mechanism is dominant during the process of proton transfer.

Two 48-nuclei silver nanocages with similar structures and compositions were synthesized by using Keggin-type polyoxometalates (POMs) BW12and SiW11Nias anionic templates. However, their photoluminescence and photocurrent properties showed obvious differences. These results suggest that POMs not only serve as anion templates in constructing silver clusters but also influence their properties.

Converting solar energy into storable hydrogen energy by employing green photocatalytic technology offers a reliable alternative for meeting the energy crisis. The polyoxometalates are a promising candidate for hydrogen production photocatalysts because of their unique electronic and structural properties and controllable design at the molecular level. Introducing noble metals was proven to be an effective method to greatly enhance the photocatalytic efficiency of polyoxometalates. Herein, two unprecedented compounds of hexameric Ru-POMs, Na4H10[As2RuIV2W11O18(OH)4(H2O)6{AsW8RuIVO31(OH)Cl}2(B-β-AsW9O33)4]·93H2O (1) and Na2H19[AsRuIII2W11O20(OH)2(H2O)6(RuIIICl3)(B-β-AsW9O33)6]·90H2O (2), were successfully self-assembled. The H2evolution rates of 1and 2under optimal conditions were 3578.75 and 3027.69 μmol h–1g–1with TONs of 255 and 205, respectively. The stability of 1was demonstrated by a series of characterizations. Besides, a possible photocatalytic mechanism was proposed.

A novel circularly polarized (CP) Yagi–Uda antenna based on element rotation is proposed in this communication. At first, the two-potential integral equations are adopted to analyze the three-element-rotation CP Yagi–Uda antenna, which is composed of a driven, a reflector, and director elements with certain rotation axial angles. Then, according to the CP scheme, the four and five-element-rotation Yagi–Uda antennas are designed and analyzed for practical applications. Finally, the five-element-rotation CP Yagi–Uda antenna is fabricated, and its measured results show an impedance bandwidth of 13.30% (2.24–2.56 GHz), AR bandwidth of 14.49% (2.24–2.59 GHz), and peak gain of 7.69 dBic. Due to wider impedance and AR bandwidths and a simple structure, the proposed scheme will provide a novel insight for the design of CP Yagi–Uda antennas.

A novel Ru(III)-containing tungstoantimonate Na16H22[(B-β-SbW9O33)6(W3RuO7)2(W4O11)]·118H2O (1) hexamer was successfully synthesized using the hydrothermal synthesis method. Analysis by single-crystal X-ray diffraction revealed that the polyanion comprises six trivacant Keggin-type [B-β-SbW9O33]9–units interconnected by six {WO6} and six Ru/W disorder octahedra, resulting in an intriguing cyclohexane boat-like conformation. Compound 1exhibits favorable proton conductivity, with a measured conductivity (σ) of 5.41 × 10–3S cm–1at 333 K and 55% relative humidity (RH). The activation energy (Ea) of compound 1was determined to be 0.40 eV, providing evidence that its proton conductivity conforms to the Grotthus mechanism

The development of visible-light-responsive, environmentally friendly, and reusable photocatalysts for organic oxidation reactions is of vital significance. Herein, four polyoxometalate-based metal–organic frameworks (POMOFs) were synthesized and systematically characterized by assembling the paddlewheel complex Rh2(OAc)4and various polyoxometalates (POMs). Single-crystal X-ray diffraction analysis revealed that the four POMOFs were isomorphic and possessed rare structural features among the POMOFs, with POMs as nodes and Rh2(OAc)4as linkers. As expected, the activities of the four POMOFs for the photocatalytic oxidative coupling of benzylamine were better than that of Rh2(OAc)4or POMs individually, which was ascribed to the synergistic effect between them, and the intrinsic reasons for the difference in the activity were explained via electrochemical measurements. In particular, the product imine yield reached 96.1% with NaRh-SiW12as the catalyst and a turnover number and a turnover frequency of 480.5 and 120.5 h–1, respectively, while the product yield remained as high as 92% after three repetitions, evidencing its high stability. Moreover, the higher activities of the four POMOFs for the selective epoxidation of various alkenes reaffirm the synergistic effect between Rh2(OAc)4and POMs.

A d-methionine-bonded nanosized arsenotungstate, Ba9K10H6[{As2W19O67(H2O)}2{AsW9O33}2{W3O6(H2O)(d-Met)}2{W2O4(OH)(d-Met)}]·60H2O [1; d-Met = d-methionine (C5H11NO2S)], is constructed without the use of lanthanide ions. The polyanion of 1contains two {As2W19O67(H2O)}14–building blocks and two {B-β-AsW9O33}9–subunits, integrated together with a {W2O4(OH)(d-Met)}2+and two {W3O6(H2O)(d-Met)}5+subclusters. Interestingly, 1displays a highly reversible photocoloration property with a half-life (t1/2) time measured as about 0.793 min.

The bifurcated fracture is distributed in nature, and its deformation and destruction occur under natural and man-made force. The study is carried out based on experiments and simulations to analyze the behavior of rock with bifurcated fractures under pressure. Bifurcated fracture causes the bending of the rock blocks on both sides and produces the tensile fractures under pressure. The lateral blocks with tensile fracture lead to the displacement of the intermediate block. By changing the bifurcated angle between fractures, the displacement characteristics of rock caused by block fractures are studied. The angle affects deformation, stress field, fracture mechanism, and displacement of rock with bifurcated fractures. The angle changes the stress magnitude and distribution of the rock blocks, affecting the initiation and expansion of the tension fractures at the bending side of the rock. Peak value of stress decreases with the decrease in bifurcated angle. The displacement difference between the two blocks will become larger. With the decrease in the pressure, deformation increases with time and the deformation rate decreases with time. The smaller the angle, the more difficult it is for the intermediate block to move out. Bifurcated angle of rock fracture has significant effects on the stability of the rock. The results could provide a reference for the stability of rock engineering.

The development of solar-driven organic synthesis processes as an alternative to conventional thermo-catalytic technologies is of great research significance in academia and industry. Herein, we looked into the photoinduced Baeyer–Villiger oxidation of cyclohexanone based on the Mukaiyama method for the first time. We fabricated a crystalline polyoxometalate-based metal–organic framework photocatalyst, CR-SiW12, which represents the first example of trinuclear ruthenium clusters involved in the construction of polyoxometalate-based metal–organic frameworks. The cyclohexanone was efficiently converted to ε-caprolactone under visible light (>400 nm) irradiation with CR-SiW12as the catalyst, with a reaction turnover number and turnover frequency recorded as 941 and 274.5 h–1, respectively, and the apparent quantum yield at 465 nm was measured to be 8.4%. Moreover, CR-SiW12exhibited high structural stability and reaction reusability where reaction yield remained high at 91.3% after five consecutive reaction cycles. This work offers a promising strategy for accomplishing Baeyer–Villiger oxidation reactions under green conditions.

The trend estimate of vegetation change is essential to understand the change rule of the ecosystem. Previous studies were mainly focused on quantifying trends or analyzing their spatial distribution characteristics. Nevertheless, the uncertainties of trend estimates caused by spatiotemporal scale effects have rarely been studied. In response to this challenge, this study aims to investigate spatiotemporal scale effects on trend estimates using Moderate-Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and Gross Primary Productivity (GPP) products from 2001 to 2019 in the Qinghai-Tibet Plateau (QTP). Moreover, the possible influencing factors on spatiotemporal scale effect, including spatial heterogeneity, topography, and vegetation types, were explored. The results indicate that the spatial scale effect depends more on the dataset with a coarser spatial resolution, and temporal scale effects depend on the time span of datasets. Unexpectedly, the trend estimates on the 8-day and yearly scale are much closer than that on the monthly scale. In addition, in areas with low spatial heterogeneity, low topography variability, and sparse vegetation, the spatiotemporal scale effect can be ignored, and vice versa. The results in this study help deepen the consciousness and understanding of spatiotemporal scale effects on trend detection.

A synchronous crystal- and microstructure-dependent strategy was implemented to synthesize the organic hybrid antimoniotungstate layered ionic crystal Na5.5H6.5[(SbW9O33)2{WO2(OH)}2{WO2}RuC7H3NO4]·36H2O, and the layered structure was constructed through the Na+bridged sheet and the hydrogen-bonded layers. It displayed an effective proton conductivity of 2.97 × 10–2S cm–1at 348 K and 75% RH, owing to the complete interlayer confined hydrogen-bond network formed by the hydrogens of interlayer crystal waters, organic ligands ({RuC7H3NO4}2+, {C7H3NO4} is formed by the hydrolysis of pyridine 2,5-dicarboxylic acid (C7H5NO4)), and acidic protons (H+), along with the interlayer domain as a transport channel. Furthermore, the hydrogen-bond network originating from interlayer organic ligands and acidic protons was more stable at a higher temperature of 423 K, preserving a high conductivity of 1.99 × 10–2S cm–1.

Two novel arsenotungstate species, [As4W48O168]36–(1a) and [As2W21O77(H2O)3]22–(2a), have been successfully isolated under a one-pot synthetic method. 1ais the second largest arsenotungstate cluster and is constructed from four {AsW12} clusters combined together. 2acan be described as lacunary sites of {As2W19} filled by {W2O8} units. Compounds 1and 2exhibit proton conductivity properties, and the conductivity value of 1is 5.0 × 10–3S cm–1at 98% relative humidity and 75 °C. This work proves that the lattice water molecules and polyoxoanions can participate in the formation of a hydrogen bond, acting as effective pathway for intermolecular proton conduction.

The development of novel high-efficiency photocatalysts to solve the bottleneck problems of low efficiency and harsh conditions of organic oxidation reactions is of vital significance. In this paper, a novel hybrid polyoxometalate (POM) crystal, (C2H8N)6[SiW11CdO39][Ru(bpy)2(dcbpy)]·DMF·5.5H2O (RuCd–SiW), was synthesized by combining the metalloligand [Ru(bpy)2(dcbpy)] with the oxidation catalyst POM. The introduction of the metalloligand extended the light absorption range of RuCd–SiWto the visible region, while electrochemical measurements demonstrated its potential as an excellent photocatalyst. Under visible light (λ > 400 nm) irradiation with O2as the sole oxidant, RuCd–SiWshowed highly efficient photocatalytic activity for the selective oxidation of thioanisole to (methylsulfoxide)benzene with a yield of 99.5%, a turnover number of 497.5, and a turnover frequency of 103 h–1. Particularly, the yield of (methylsulfoxide)benzene was still higher than 99% after five rounds of recycling, demonstrating its high stability and recyclability.

The spatial scale mismatch between satellite and in situ-based measurements can be reduced by deploying multiple in situ sites within the coarse pixel. However, upscaling in situ measurements from the ground-support scale to the coarse pixel scale is still necessary due to their “point” measurement characteristics. The previous upscaling methods were generally developed merely for the in situ measurements. Nevertheless, the uncertainty of in situ measurements, such as measurement errors and spatial representativeness errors, was not dealt with. Consequently, the upscaling results inevitably suffer from errors, which will finally propagate into the pixel scale ground “truth.” For the first time, this study presents an improved upscaling method with the consideration of the uncertainty of in situ measurements based on the error theory and measurement adjustment theory. The effectiveness of the corrected upscaling coefficients was evaluated by comparing the accuracy of the corrected upscaling results with those based on the upscaling coefficients without considering the uncertainty of in situ measurements. The results indicate that the accuracy of the upscaling results can be enhanced by 11.06% in the condition in which in situ measurements suffer from large uncertainty. However, if the uncertainty of in situ measurements is negligible, the corrected upscaling model is not necessary because it does not bring many benefits. Although the effectiveness of this method was only tested on a limited study area, it makes an important first step toward a higher precision pixel-scale ground “truth,” especially when the uncertainty of in situ measurements is nonnegligible.

In this communication, an ultrawideband millimeter-wave (mm-Wave) bidirectional circularly polarized (CP) monopole antenna array with sequential rotation feeding (SRF) technique is proposed. First, a broadband CP monopole antenna element is realized by utilizing the asymmetric ground plane, C-shaped ring, and rectangular stub structure. A microstrip to coplanar waveguide (CPW) transition structure is designed to feed the antenna element. Then, the SRF technique is adopted to further improve the axial ratio (AR) bandwidth of the 2 $\times2$ CP subarray. Finally, a $4\times4$ CP array is designed to further enhance the gain for mm-Wave applications. Measured results show that the proposed $4\times4$ CP array exhibits the −10 dB impedance bandwidth of 102.7%, 3 dB AR bandwidths of 100.7%/101.3% in the $+\textit {z}/-\textit {z}$ -direction, and the peak gain of 15.6 dBic.

A dl-alanine covalently bonded giant arsenotungstate, namely, Na3Ba11H16[(AsW9O33)6{W2O5(H2O)(dl-Ala)}2{W3O6(H2O)(dl-Ala)}2{W2O5(dl-Ala)}] (1; dl-Ala = dl-alanine), has been synthesized and is composed of six [AsW9O33]9–fragments fused together via two [W2O5(H2O)(dl-Ala)]+segments, two [W3O6(H2O)(dl-Ala)]5+segments, and a [W2O5(dl-Ala)]+segment. This complex represents the first carboxylate-based hybrid polyoxotungstate without the introduction of lanthanide ions. Besides, compound 1demonstrates not only fast photochromic properties but also interesting proton conductivity properties, with an achieved conductivity of 2.830 × 10–4S·cm–1(65 °C, 75% relative humidity).

A novel telluroniobate, K8Na6H7{[Co(en)2(SO3)][Te4Nb24O79]}·42H2O (en = ethylenediamine), has been synthesized through a diffusion strategy. It consists of a heteropolyoxoniobate [B-β-TeNb9O33]17–cluster and isopolyoxoniobate {Nb7O22} building blocks. In addition, its structure was fully characterized by a series of spectroscopic methods. Furthermore, it exhibits an efficient catalytic performance in the transesterification of ethylene carbonate and methanol to prepare dimethyl carbonate with good catalytic reusability. Also, it demonstrates interesting proton conduction properties, with conductivity achieved at 3.05 × 10–4S cm–1(60 °C, 75% relative humidity).

Three isostructural dl-serine covalently functionalized and multinuclear lanthanide (Ln3+)-embedded arsenotungstates, K2[{As4W44O137(OH)18(H2O)2(dl-Ser)2}{Ln2(H2O)4(dl-Ser)}2{Ln(H2O)7}2]·70H2O (Ln = Sm (1), Eu (2), and Gd (3); dl-Ser = C3H7NO3), were prepared, where the centrosymmetric [{As4W44O137(OH)18(H2O)2(dl-Ser)2}{Ln2(H2O)4(dl-Ser)}2]8–polyanion consists of two {As2W19O59(OH)8(H2O)}6–fragments, integrated with a two-dl-serine-ornamented [W6O23(OH)2(dl-Ser)2{Ln2(H2O)4}2]8–segment. In addition, the photochromic transformation of solid-state compounds 1–3was observed from colorless to blue after a UV illumination of 4 min, and the decay process lasted as long as ∼20 h in the dark. The coloration kinetic half-life (t1/2) values of compounds 1, 2, and 3were calculated to be 0.597, 0.920, and 0.723 min, respectively. Furthermore, the luminescent properties and energy migration from arsenotungstates and organic chromophores to Sm3+and Eu3+ions in 1and 2have been intensively investigated. Further analysis manifests that 1possesses an effective luminescent switchable behavior, triggered by its fast-responsive photochromism effect.

Two multi-Rh-incorporated polyoxometalates [NH2(CH3)2]10[Na4(H2O)8]H3[As4W42O142(OH)4(CH3COO)2Rh3(H2O)4]·13H2O·4[NH(CH3)2] (1) and [K4Na(H2O)6]KH10[As4W40O140Rh4(H2O)4]·34H2O (2) have been synthesized in acetate buffer solution. Polyanion 1ais built up atop of an acetate-modified rectangular framework [As4W42O142(OH)4(CH3COO)2]26–, while polyanion 2acontains a pure inorganic cryptand [As4W40O140]28–. All Rh atoms of these two compounds share the same hexa-coordinate distorted-octahedral geometry and are embedded into their cavities through As–Rh bonding with a bond length around 2.304(4)–2.436(5) Å. Besides, they not only represent structural novelty but also demonstrate controllable proton conduction properties. Catalysts 1and 2can catalyze cycloaddition of epoxides with CO2in a solvent-free system in conjunction with 1-ethyl-1-methylpyrrolidinium bromide.

Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni2(H2O)10{P4Ta6(O2)6O24}]6–(1a), [Zn(H2O)4{P4Ta6(O2)6O24}]8–(2a) and [Cd(H2O)4{P4Ta6(O2)6O24}]8–(3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 10–3S/cm (85 °C, 90%RH).

By integration of {Ln(H2O)6}3+into organophosphonate-based polyoxometalates, three Ln-containing organophosphonate-functionalized polyoxomolybdates Na1.5H1.5[{Ln(H2O)6}2{(Mo3O8)(O3PC(C3H6NH3)OPO3)}4]·(CH3CO2)·43H2O (Ln = Eu (1), Tb (2), and Dy (3)) are successfully prepared and systematically characterized. The X-ray crystallography analyses display complexes 1–3crystallize in the C2/cspace group of the monoclinic system and compose several distinctive tetramer windmill-like compounds that further assemble into two-dimensional (2D) frameworks associated with the {Ln(H2O)6}3+core. The fluorescence spectra of 1–3show red, green, and chartreuse emissions, respectively, originating in the typical f–f transitions of Ln3+ions. More interestingly, complex 3shows the field-induced single-molecule magnet (SMM) properties, resulting from the fact that [(Mo3O8)4{O3PC(C3H6NH3)OPO3}4]8–offers excellent magnetic isolation for Dy3+ions by the nearest Dy1···Dy2 distance of 11.207 Å. The study demonstrates that the incorporation of {Ln(H2O)6}3+into organophosphonate-based polyoxomolybdates is an effective synthetic strategy in implementing late-model opto-magnetic materials.

Fourteen lanthanide (Ln)-containing hetero selenato-phosphato-peroxopolyoxoniobates in three series: (1) Cs2{[Ln(H2O)4][H4P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Ce (I-Ce), Pr (I-Pr), Sm (I-Sm), Eu (I-Eu), Gd (I-Gd); I-Ce, I-Pr, I-Eu, I-Gdn= 12; I-Smn= 16]; (2) Cs2K3{[Ln(H2O)6][H2.5P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Dy (II-Dy), Tm (II-Tm), Yb (II-Yb), Lu (II-Lu); II-Dyn= 14; II-Tmn= 24; II-Yb, II-Lun= 13]; (3) Cs5K2Hm{[Ln(H2O)6][P2Se2Nb6(O2)6O22]}2{[Lnx(H2O)y]2[P2Se2Nb6(O2)6O22]}·nH2O [Ln = Ho (III-Ho), Er (III-Er), Tm (III-Tm), Yb (III-Yb), Lu (III-Lu), III-Ho-III-Ybm= 5, x= 1; y= 5; III-Lum= 6.5; x= 0.75; y= 4; III-Ho–III-Tmn= 19, III-Ybn= 34; III-Lun= 31], have been isolated by a one-pot reaction and structurally characterized by various physical and chemical analyses. These compounds represent the first group of Ln-functionalized polyoxoniobates with mixed heteroatoms. In addition, the photoluminescence properties of compounds I-Sm, I-Eu, and II-Dywere measured, and the time-resolved emission spectra showed that the {P2Se2Nb6} segment contributed to the energy transfer from the polyoxoniobate units to the Ln3+center, which effectively promoted the emission of the Ln3+center.

Two structurally intriguing Ru-containing isopolyoxometalates [(Ru(OH))2O(W5O18)2]8–(1) and [(W5O18)(Ru2W8O31)]12–(2) were constructed from subtly different conditions. Single-crystal X-ray diffraction indicated that the precise pH modification has allowed us to trap a diruthenium-oxo core within different isopolyoxotungstate species. Compound 1is the first sandwich-type ruthenium isopolyoxotungstate consisting of a linear {(HO)Ru–O–Ru(OH)} unit and two Lindqvist-type {W5} building blocks, while a ligand replacement of {W5} with an unusual {W8} ring in the case of compound 1produced a unique embedded-type compound 2with a quasi-linear {Ru–O–Ru} core. In addition to being determined in the solid state, crystal structures of 1and 2were also confirmed by 183W nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization–mass spectrometry (ESI–MS) in solution. 183W NMR spectrum demonstrated that the two-line pattern of 1(with approximately 4:1 relative intensities) is consistent with the pseudo-D2hsymmetry observed in the solid state. However, two other lines were observed in 2according to the C2vsymmetry but not in accord with the expected 4/4/4/1 ratio in the crystalline state, which indicated that the structure of 2could not be maintained completely in aqueous solution. After recrystallizing the solid sample of 2in water, the crystal structure of 2partly converted to the structure of 1, and the transformation was determined by the combined results of 183W NMR, ESI–MS and single-crystal X-ray diffraction measurements. Catalytic investigations showed that their sodium salts presented excellent photocatalytic activities toward the benzylamine oxidation reaction induced by visible light (λ > 400 nm). The structures of the two compounds can still be maintained without a significant yield decrease after five continuous reaction cycles. Furthermore, both catalysts 1and 2could proceed with the oxidative coupling reaction smoothly for most of the primary benzylamine derivatives bearing various functional groups (H, F, Cl, Br, and Me) in good to excellent yields.

Two isostructural valence tautomeric (VT) complexes with different critical temperatures were prepared and fully investigated through a series of magnetic, structural, spectral, and differential scanning calorimetry evidence. The kinetic effect in the VT complex was observed for the first time through scan-rate-dependent studies and further validated by annealing tests.

Two cases of lanthanide (Ln)-implanted arsenotungstates, K17Na2H5[{(As2W19O67(H2O))Ln(H2O)2}2(C2O4)]·87H2O (Ln = Eu (1), Ln = Tb (2)) and their codoped derivatives EuxTb1–x-POM (x= 0.01 (3), x= 0.04 (4), x= 0.1 (5), x= 0.2 (6)) were prepared and further characterized by powder X-ray diffraction, infrared spectra, and thermogravimetric analyses. An X-ray structural analysis of 1and 2indicates that they both present a dimeric oxalate-bridged Ln3+-implanted lanthanide arsenotungstate polyanion structure. Under the O → W LMCT excitation at 265 nm of arsenotungstate polyanions, the emissions of Ln3+ions in 1and 2are sensitized and the lifetimes are prolonged. Codoped compounds 3–6demonstrate a color-tunable emission from green to red by adjusting the Eu3+/Tb3+ratio. Emission spectra and time-resolved emission spectroscopic studies were performed for 3to further authenticate the energy transfer processes from excited arsenotungstates to the Eu3+and Tb3+metal ions and also between the Eu3+and Tb3+centers. More interestingly, 1is an effective fluorescent probe for the recognition and detection of Ba2+ions in aqueous solution. The optical properties of the Ln-implanted arsenotungstate compounds not only expressly reveal distinctive energy transfer processes in those compounds but also broaden the application of POM-based materials in the fluorescence sensing field.

Design and synthesis of efficient small organic molecule-based electrooxidation catalysts in replacing conventional oxygen evolution reaction (OER) catalysts has been considered as an alternative path to enable large-scale renewable energy storage. In contrast to OER, alcohol oxidation reactions can be implemented at lower applied potentials along with generating higher value-added byproducts than oxygen. Here, the ultrafine Ni/WC hybrid nanoparticles (NPs) were successfully synthesized via an in situtrapping and space-confinement pyrolysis strategy. The as-synthesized Ni/WC hybrid NPs exhibit high electrooxidation performances in oxidizing methanol, ethanol, iso-propanol, ethylene glycol, and propylene glycol in alkaline solution. Particularly, for the methanol oxidation reaction, Ni/WC NPs demonstrate high reaction activity (specific activity: 325 mA cm–2at 0.6 V vs Ag/AgCl/3.5 M KCl; mass activity: 1363 mA mg–1) and excellent stability (catalytic current drops ∼6.8% after 4 h). In the first 6 h of the electrolysis process, methanol was effectively converted into formate with ca. 93.8% Faraday efficiency. Based on in situIR spectra and control catalyst experiments, tungsten carbide (WC) and nickel oxyhydroxide (NiOOH, derived from Ni) species are capable of activating different functional groups of methanol. More interestingly, their hybrid structure (Ni/WC) demonstrates improved catalytic performance in converting methanol into a formate product for the synergistic effect.

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH3)4]6H20[{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]2Cl2·98H2O [Ln = Sm (1), Eu (2), and Gd (3)] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]224–are all established by four monolacunary Dawson-type [P2W17O61]10–segments, encapsulating a Ln3+ion with two benzoates coordinating to the Ln3+ions. 1–3exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of 1and 2display characteristic emissions of Ln components based on 4f–4f transitions. Time-resolved emission spectra of 1and 2were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu3+. In particular, 1shows an effectively switchable luminescence behavior induced by its fast photochromism.

Developing new catalysts for highly efficient and selective oxidation of saturated C–H bonds is significant due to their thermodynamic strength. Via incorporation of PW12O403–, pyridine-2,5-dicarboxylic acids (pydc), and Fe(III) ions into one framework, a new polyoxometalate-based metal–organic framework, [HFe4O2(H2O)4(pydc)3PW12O40]·10.5H2O (FeW–PYDC), was successfully prepared by a hydrothermal method. Interestingly, FeW–PYDCfeatures a three-dimensional porous structure with {Fe4O2} interconnecting with PW12O403–units. FeW–PYDCdisplayed excellent performance in the selective oxidation of C–H bonds of alkylbenzenes with high conversion (95.7%) and selectivity (96.6%). As an effective heterogeneous catalyst, FeW–PYDCdemonstrates good reusability and structural stability.

A copper-containing polyoxometalate-based metal–organic framework (POMOF), CuI12Cl2(trz)8[HPW12O40] (HENU-7, HENU = Henan University; trz = 1,2,4-triazole), has been successfully synthesized and well-characterized. In addition, the excellent catalytic ability of HENU-7has been proved by the selective oxidation of diphenylmethane. Under the optimal conditions, the diphenylmethane conversion obtained over HENU-7is 96%, while the selectivity to benzophenone is 99%, which outperforms most noble-metal-free POM-based catalysts. Moreover, HENU-7is stable to reuse for five runs without an obvious loss in activity and also can catalyze the oxidation of different benzylic C–H with satisfactory conversions and selectivities, which implied the significant catalytic activity and recyclability.

The production, processing, transportation, and consumption of fresh food have a significant impact on the sustainable development of the whole fresh food supply chain. There are relatively few methods and techniques to qualitatively analyze the dynamic driving factors of fresh food sustainable supply-chain management (SSCM). To solve this problem, this paper first sorts out the drivers dimensions and specific impact indicators of fresh food SSCM through the literature. Then, the integration of rough set theory and decision laboratory analysis reveals the internal strength, external connection, and comprehensive influence degree, while the prominence and relation of the driving factors are tested which reflects their priority. The results show that the competitiveness of the supply chain, food security, and strategic are the main driving factors of SSCM. Attention should be paid to green technology, product design, and green logistics. The creation and distribution of added value, as well as food security management, should be improved.

Research on the facet-dependent anisotropic proton conduction of single crystals is advantageous to visualize the molecular level mechanism of polyoxometalate (POM)-based crystalline proton-conducting materials. Herein, we constructed a novel ring-shaped trimeric isopolytungstate {(RuW11O37)O}318–(1a) with an inner hydrophobic space and an outer hydrophilic surface. After assembly through the hydrated cation linkers, polyanion 1arings formed the single-crystal Rb11Na6H·1a·36H2O (1) with (01̅0), (101), and (1̅11) faces, which have different sizes and types (hydrophilic-Grotthuss-type and/or hydrophobic-Vehicle-type) of proton transport channels. Accordingly, proton conductivity (σ) of single-crystal 1can reach 3.84 × 10–2S cm–1along the direction perpendicular to the (01̅0) face at 358 K under 85% relative humidity (RH), which is equivalent to that of crystal pellet (2.09 × 10–2S cm–1) and accompanied by the ratio of σ(01̅0):σ(101):σ(1̅11)= 121:5:1. It reveals a visible (01̅0) facet-dependent proton-conducting pathway in the large-sized hydrophilic pore channels through a water-induced hydrogen bond network under the Grotthuss hopping mechanism.

The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal. Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method. The monomer, K11Li[P2W12(TaO2)6O56]·19H2O (1), is composed of {P2W12} and 6 {Ta(O2)} building blocks, similar to [P2W12(NbO2)6O56]12−. Monomer 1polymerized to form two cis-transdimers, K13Li6H-cis-[P2W12Ta4(TaO2)2O59]2·61H2O (2) and KNa3Li4H12-trans-[P2W12Ta4(TaO2)2O59]2·37H2O (3). Compounds 1–3can serve as a structural motif to manufacture additional fascinating molecular clusters, promoting the advancement of POM chemistry. In contrast to [P2W12(NbO2)6O56]12−, compound 1exhibits exceptional stability, evidenced by ESI-MS, IR, and NMR spectroscopy. In addition, 2and 3exhibit high proton conductivity and superior water adsorption properties.

A novel dysprosium(III)-containing polytungstoarsenate, [{(AsW9O33)3Dy2(H2O)4W4O9(H2O)}2(NH2(CH2PO3)2)]33–, comprising two identical subunits bridged by an organophosphonate ligand shows single-molecule-magnet (SMM) behavior. Magnetic studies reveal that this complex exhibits a butterfly-shaped hysteresis loop up to 8 K, and a thermally activated energy barrier of 101(5) K reached a breakthrough among all polyoxometalate-supported SMMs.

Used as a ventilator for assisting victims of polio, the barospirator was described by Swedish physician-scientist Torsten Thunberg in 1924. An immediate predecessor of the iron lung of Philip Drinker, the barospirator fully encased the entire body. Cyclic air-pressure changes within the chamber achieved ventilation during equilibrations of intrapulmonary and ambient pressures. Pulmonary medicine innovator Alvan Leroy Barach used a modified barospirator for lung rest as a treatment of tuberculosis in the 1940s. Adverse effects included damage to patients' tympanic membranes. Despite its limited clinical success, the barospirator was successfully used by one of Drinker's competitors, John H. Emerson, to invalidate Drinker's US patent filings.

By adopting different crystal growth methods, two novel organic–inorganic hybrids, [{Cu(phen)}6(H2O)(Te5Nb15.5Cu0.5O57)]3.5–and its dimer, have been successfully synthesized. These are fabricated by simple compound reactions and directed by the tellurite anions, which act as heteroanion templates and linkers, as well as a pendant ligand. The compounds were characterized by IR spectra, UV/vis, thermogravimetric analysis, and single crystal X-ray diffraction. Furthermore, the solution behavior was also investigated.

An organic–inorganic hybridized polyoxotungstate which contains two kinds of covalently linked tungstate clusters in its polyanion has been obtained. The three clusters are connected by glutamic acid molecules and europium atoms through Eu–O–C bonds. The cluster in the middle position is a tetramer. Two of the same clusters at two sides are dimers that are functionalized by glutamic acid molecules. The solid-state luminescence of this compound exhibited the characteristic emission of Eu3+centers with a lifetime of 232 μs.

A novel class of organophosphonate-based polyoxomolybdate derivatives, K4H5[Ln3(H2O)14{(Mo8O24)(O3PCH2COO)3}2]·23H2O (Ln = Gd (1Gd), Tb (2Tb), Dy (3Dy)), have been fully investigated by a few characterization methods such as single-crystal X-ray crystallography, XRPD, elemental analysis, TGA, and IR spectra. The magnetic properties of 1Gd, 2Tb, and 3Dywere investigated, as well as the solid-state luminescence properties of 2Tband 3Dy. The catalysis properties of 1Gd, 2Tb, and 3Dyfor thioether oxidization have been investigated using hydrogen peroxide (H2O2) as an oxidant. The catalysis study demonstrated the efficient and selective conversion of various thioethers to their corresponding sulfones in excellent yields.

A novel organic−inorganic hybrid phosphovanado-molybdate Na(H2O)6[Cu(2,2′-bipy)3]2[Cu(1,2-dap)2(H2O)]6H[Cu(1,2-dap)2{PMoVI8VIV4O40(VIVO)2Cu(1,2-dap)2}]6·2H2O (1) (1,2-dap = 1,2-diaminopropane, 2,2′-bipy = 2,2′-bipyridine) has been hydrothermally synthesized and characterized by elemental analyses, IR, TG-DTA, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRPD), and single crystal X-ray diffraction. Interestingly, 1represents the first example of cyclohexane-like ring-shaped phosphovanadomolybdate constructed from six bicapped pseudo-Keggin clusters [PMoVI8VIV4O40(VIVO)2Cu(1,2-dap)2]5−linked by six [Cu(1,2-dap)2]2+linkers. Notably, adjacent rings are connected together, forming the 3-D supramolecular structure through hydrogen bonding interactions.

In this paper, we have successfully synthesized a structurally novel heteropolytungstate via coordination of four {Ru(C6H6)} and trivacant {TeW9O33} clusters, formulated as Cs4Na2H2[Te2W20O72(H2O){(C6H6)Ru}4]·12H2O (1). Compound 1inherited the strong absorption of [Ru(C6H6)Cl2]2in the visible region and {TeW9O33} in the UV region, providing a good basis for photocatalysis. As expected, compound 1showed good photocatalytic activity in the visible-light-driven reduction of nitrobenzene using N2H4·H2O as a reductant with a yield of 99.8%, a high turnover number (TON = 330), and a high turnover frequency (TOF = 24 h–1). The cyclic experiment of nitrobenzene reduction indicated that compound 1was an effective and stable heterogeneous catalyst. Finally, the nitrobenzene reduction pathway was affirmed using condensation with azobenzene as a reaction intermediate based on control experiments.

A 6-Ti-substituted polyoxometalate, (NH4)5Cs7Na3H2[Cs@(Ti2GeMo10O39)3]·34H2O (1), was synthesized by reacting (NH4)6Mo7O24·4H2O, GeO2, and TiOSO4through the conventional aqueous method. Polyanion 1ais composed of three {Ti2GeMo10} segments linked by Ti–O–Ti linkages and shows a trefoil-shaped structure. Furthermore, one Cs+cation is encapsulated in the cavity of 1a. Notably, it possesses the highest number of Ti centers among the reported polyoxomolybdates. In addition, serving as a high-efficiency heterogeneous catalyst, 1enables the conversion of methyl phenyl sulfide within 20 min, yielding 96.4% of the corresponding sulfoxide with good recyclability.

Polyoxometalates (POMs), emerging as a new class of porous molecular materials, play a promising role in homo- and heterogeneous catalysis. Among them, noble-metal-decorated POMs have a profound impact as catalytic materials. Thus, it is imperative to design and structurally explore new catalysts including noble metals. Herein, two new clusters, H3[(Cp*Rh)4PMo8O32]·14H2O (1) and H5[Na2(Cp*Ir)4PMo8O34]·13H2O (2) (Cp* = pentamethylcyclopentadienyl), based on a heterooctamolybdate anionic core were successfully obtained via a one-pot reaction using [Cp*MCl2]2[M = Rh (1) and Ir (2)] and Na2MoO4in acidic conditions. Compounds 1and 2were well characterized in the solid state by single-crystal X-ray diffraction, IR, and thermogravimetric analysis and in solution by UV–vis, electrospray ionization mass spectrometry, and electrochemistry. Compounds 1and 2represent an important class of structurally isolated organometallic POM-based clusters that were successfully nanostructured onto Ni foam and electrochemically reduced after 48 h of electrolysis to M/MoO2, where M = Rh (3) and Ir (4), nanocomposite hybrid materials on a Ni foam surface in a 0.1 M KOH solution. The modified electrocatalysts (3and 4) show efficient hydrogen evolution reaction activities almost comparable to those of high-grade Pt/C at 0.1 M KOH. The nanostructured POMs [1- and 2@NF (Ni foam)] and their corresponding reduced products (3and 4) were observed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy and further proven by transmission electron microscopy (TEM) and high-resolution TEM.

The vinylene-linked covalent organic frameworks (viCOFs) have been generally synthesized in the presence of homogeneous catalysts such as KOH or trifluoroacetic acid. However, highly ordered viCOFs cannot always be obtained due to the uncommitted growth of viCOF layers in the homogeneous system with ubiquitous catalysts. Here, we propose a scalable protocol to restrict the growth of viCOFs along the two-dimensional (2D) plane by introducing a heterogeneous catalyst, polyoxometalates (POMs). With the unique Brønsted alkalinity and catalytic surface, POMs induce the growth of 2D viCOF layers along the surface of the catalytic substrate and restrain the generation of out-of-plane branches. Based on this protocol, six typical 2D viCOFs with high crystallinity and porosity were synthesized within a shorter reaction time as compared with the reported works using the common homogeneous catalysts for viCOF synthesis. On the basis of the density functional theory calculations and experimental results, a bottom intercalation growth pattern of viCOFs was revealed during the heterogeneous reaction. The unique growth pattern greatly promotes the orderly assembly of monomers, thus shortening the reaction time and improving the crystallinity of viCOFs. Furthermore, this heterogeneous catalysis strategy is suitable for the gram-scale preparation of 2D viCOFs. These results provide a novel avenue for the synthesis of high-quality viCOFs and may bring new insights into the synthetic methodology of COFs.