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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.
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The synthesis of highly efficient visible-light-responsive photocatalysts is fundamental to solving the problems of low efficiency and poor selectivity in photocatalytic organic synthesis reactions. We synthesized a crystalline polyoxometalate @metal-organic framework material {Zn4 (H2 O)8 [Ir(ppy)2 (dcbpy)]4 [SiW12 O40 ]} â 4H2 O (Ir-SiW) by self-assembly of Ir metalloligands with POMs. The introduction of Ir metalloligands extends the light absorbing range to visible light, improving the efficient utilization of solar energy. The transfer of photogenerated electrons from Ir metalloligands to SiW12 was observed under visible light irradiation, which boosted the carrier separation efficiency. The synergistic effect of the two components increased the photocatalytic thioether oxidation activity, and the product methyl phenyl sulfoxide for 2.5â h under visible light irradiation (λ >400â nm) reached 99.5 %, which was higher than those of other POM-based photocatalysts. Meanwhile, the yield of methyl phenyl sulfoxide was still higher than 97 % after three cycles, demonstrating the high stability and reusability of Ir-SiW.
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An unclassical structure of {Ru(C6 H6 )}-based polyoxometalate, Cs6 H4 [Te2 Mo12 O46 {Ru(C6 H6 )}] â 16.5H2 O (1), has been successfully constructed from {Te2 Mo12 O46 }-type heteropolymolybdate and {Ru(C6 H6 )} group, which structure type was discovered for the first time. Compound 1 not only possesses strong light-harvesting ability, but also exhibits high carrier separation efficiency and lower charge transfer resistance. Under visible light irradiation, compound 1 displayed excellent catalytic activity and circularity in the conversion of benzyl alcohol to benzaldehyde (yield=94 %; turnover number=500; turnover frequency=20.8â h-1 ). Finally, the electron paramagnetic resonance measurement and energy level matching analysis provide theoretical basis for the derivation of the reaction mechanism.
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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 1 contains 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, 1 exhibits 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 O2 as an oxidant.
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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 2 up to 2.48 × 10-2 S·cm-1 under 85 °C and 95% relative humidity. Moreover, compounds 1 and 3 exhibited fast reversible photochromic properties with allochroic half-life periods t1/2 of 1.046 and 0.544 min, respectively.
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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 D3 symmetry, has been successfully designed and synthesized by the assembly of simple materials with a one-pot hydrothermal method under acidic conditions. Also, compound 1 is 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 1 is 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 1 exhibits high proton conductivity with a conductivity value (σ) of 3.07 × 10-2 S cm-1 at 75 °C and 80% relative humidity (RH). The activation energy of compound 1 evaluated by the Arrhenius plots is 0.22 eV, which indicates that the Grotthuss mechanism is dominant during the process of proton transfer.
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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-NiMo and Ru-CoMo by 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-NiMo can 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-NiMo exhibited excellent structural stability and recyclability, producing a 90.8% yield after five cycles of recycling.
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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 1 inherited the strong absorption of [Ru(C6H6)Cl2]2 in the visible region and {TeW9O33} in the UV region, providing a good basis for photocatalysis. As expected, compound 1 showed 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 1 was 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.
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A 6-Ti-substituted polyoxometalate, (NH4)5Cs7Na3H2[Cs@(Ti2GeMo10O39)3]·34H2O (1), was synthesized by reacting (NH4)6Mo7O24·4H2O, GeO2, and TiOSO4 through the conventional aqueous method. Polyanion 1a is 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, 1 enables the conversion of methyl phenyl sulfide within 20 min, yielding 96.4% of the corresponding sulfoxide with good recyclability.
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Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a severe disease that affects the yield and quality of wheat. Popularization of resistant cultivars in production is the preferred strategy to control this disease. In the present study, the Chinese wheat breeding line Jimai 809 showed excellent agronomic performance and high resistance to powdery mildew at the whole growth stage. To dissect the genetic basis for this resistance, Jimai 809 was crossed with the susceptible wheat cultivar Junda 159 to produce segregation populations. Genetic analysis showed that a single dominant gene, temporarily designated PmJM809, conferred the resistance to different Bgt isolates. PmJM809 was then mapped on the chromosome arm 2BL and flanked by the markers CISSR02g-1 and CIT02g-13 with genetic distances 0.4 and 0.8 cM, respectively, corresponding to a physical interval of 704.12-708.24 Mb. PmJM809 differed from the reported Pm genes on chromosome arm 2BL in origin, resistance spectrum, physical position and/or genetic diversity of the mapping interval, also suggesting PmJM809 was located on a complex interval with multiple resistance genes. To analyze and screen the candidate gene(s) of PmJM809, six genes related to disease resistance in the candidate interval were evaluated their expression patterns using an additional set of wheat samples and time-course analysis post-inoculation of the Bgt isolate E09. As a result, four genes were speculated as the key candidate or regulatory genes. Considering its comprehensive agronomic traits and resistance findings, PmJM809 was expected to be a valuable gene resource in wheat disease resistance breeding. To efficiently transfer PmJM809 into different genetic backgrounds, 13 of 19 closely linked markers were confirmed to be suitable for marker-assisted selection. Using these markers, a series of wheat breeding lines with harmonious disease resistance and agronomic performance were selected from the crosses of Jimai 809 and several susceptible cultivars. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-024-01467-8.
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Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a serious threat to wheat (Triticum aestivum L.) production. Narrow genetic basis of common wheat boosted the demand for diversified donors against powdery mildew. Aegilops tauschii Coss (2n = 2x = DD) and emmer wheat (2n = 4x = AABB), as the ancestor species of common wheat, are important gene donors for genetic improvement of common wheat. In this study, a total of 71 Ae. tauschii and 161 emmer wheat accessions were first evaluated for their powdery mildew resistance using the Bgt isolate E09. Thirty-three Ae. tauschii (46.5%) and 108 emmer wheat accessions (67.1%) were resistant. Then, all these accessions were tested by the diagnostic markers for 21 known Pm genes. The results showed that Pm2 alleles were detected in all the 71 Ae. tauschii and only Pm4 alleles were detected in 20 of 161 emmer wheat accessions. After haplotype analysis, we identified four Pm4 alleles (Pm4a, Pm4b, Pm4d, and Pm4f) in the emmer wheat accessions and three Pm2 alleles (Pm2d, Pm2e, and Pm2g) in the Ae. tauschii. Further resistance spectrum analysis indicated that these resistance accessions displayed different resistance reactions to different Bgt isolates, implying they may have other Pm genes apart from Pm2 and/or Pm4 alleles. Notably, a new Pm2 allele, Pm2S, was identified in Ae. tauschii, which contained a 64-bp deletion in the first exon and formed a new termination site at the 513th triplet of the shifted reading frame compared with reported Pm2 alleles. The phylogenetic tree of Pm2S showed that the kinship of Pm2S was close to Pm2h. To efficiently and accurately detect Pm2S and distinguish with other Pm2 alleles in Ae. tauschii background, a diagnostic marker, YTU-QS-3, was developed, and its effectiveness was verified. This study provided valuable Pm alleles and enriched the genetic diversity of the powdery mildew resistance in wheat improvement.
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Aegilops , Ascomicetos , Resistência à Doença , Doenças das Plantas , Triticum , Triticum/genética , Triticum/microbiologia , Triticum/imunologia , Ascomicetos/fisiologia , Ascomicetos/genética , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/genética , Resistência à Doença/genética , Aegilops/genética , Aegilops/microbiologia , Genes de Plantas/genética , Alelos , HaplótiposRESUMO
Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a serious fungal disease that critically threatens the yield and quality of wheat. Utilization of host resistance is the most effective and economical method to control this disease. In our study, a wheat breeding line ShiCG15-009, released from Hebei Province, was highly resistant to powdery mildew at all stages. To dissect its genetic basis, ShiCG15-009 was crossed with the susceptible cultivar Yannong 21 to produce F1, F2 and F2:3 progenies. After genetic analysis, a single dominant gene, tentatively designated PmCG15-009, was proved to confer resistance to Bgt isolate E09. Further molecular markers analysis showed that PmCG15-009 was located on chromosome 2BL and flanked by markers XCINAU130 and XCINAU143 with the genetic distances 0.2 and 0.4 cM, respectively, corresponding to a physic interval of 705.14-723.48 Mb referred to the Chinese Spring reference genome sequence v2.1. PmCG15-009 was most likely a new gene differed from the documented Pm genes on chromosome 2BL since its different origin, genetic diversity, and physical position. To analyze and identify the candidate genes, six genes associated with disease resistance in the candidate interval were confirmed to be associated with PmCG15-009 via qRT-PCR analysis using the parents ShiCG15-009 and Yannong 21 and time-course analysis post-inoculation with Bgt isolate E09. To accelerate the transfer of PmCG15-009 using marker-assisted selection (MAS), 18 closely or co-segregated markers were evaluated and confirmed to be suitable for tracing PmCG15-009, when it was transferred into different wheat cultivars.
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Melhoramento Vegetal , Triticum , Triticum/genética , Triticum/microbiologia , Mapeamento Cromossômico/métodos , Marcadores Genéticos , Genes de Plantas/genética , Resistência à Doença/genética , Erysiphe , Doenças das Plantas/genética , Doenças das Plantas/microbiologiaRESUMO
KEY MESSAGE: Host resistance conferred by Pm genes provides an effective strategy to control powdery mildew. The study of Pm genes helps modern breeding develop toward more intelligent and customized. Powdery mildew of wheat is one of the most destructive diseases seriously threatening the crop yield and quality worldwide. The genetic research on powdery mildew (Pm) resistance has entered a new era. Many Pm genes from wheat and its wild and domesticated relatives have been mined and cloned. Meanwhile, modern breeding strategies based on high-throughput sequencing and genome editing are emerging and developing toward more intelligent and customized. This review highlights mining and cloning of Pm genes, molecular mechanism studies on the resistance and avirulence genes, and prospects for genomic-assisted breeding for powdery mildew resistance in wheat.
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Melhoramento Vegetal , Triticum , Triticum/genética , Edição de Genes , Genômica , Sequenciamento de Nucleotídeos em Larga EscalaRESUMO
A novel Ru(III)-containing tungstoantimonate Na16H22[(B-ß-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-ß-SbW9O33]9- units interconnected by six {WO6} and six Ru/W disorder octahedra, resulting in an intriguing cyclohexane boat-like conformation. Compound 1 exhibits favorable proton conductivity, with a measured conductivity (σ) of 5.41 × 10-3 S cm-1 at 333 K and 55% relative humidity (RH). The activation energy (Ea) of compound 1 was determined to be 0.40 eV, providing evidence that its proton conductivity conforms to the Grotthus mechanism.
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Two novel arsenotungstate species, [As4W48O168]36- (1a) and [As2W21O77(H2O)3]22- (2a), have been successfully isolated under a one-pot synthetic method. 1a is the second largest arsenotungstate cluster and is constructed from four {AsW12} clusters combined together. 2a can be described as lacunary sites of {As2W19} filled by {W2O8} units. Compounds 1 and 2 exhibit proton conductivity properties, and the conductivity value of 1 is 5.0 × 10-3 S cm-1 at 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.
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A high-nuclearity carboxylic-modified heteropolyoxovanadate, Na2K10H15[P8VIV24(tart)15(H2O)15(OH)O51]·58H2O [1, tart = C4H2O6], has been successfully synthesized by a conventional aqueous method under mild conditions. The crystallographic study reveals that compound 1 crystallizes in the tetragonal I41/a space group and is composed by a trilayer saddle-like polyoxoanion {P8V24}. Two {V3(tart)(H2O)O11} as linking units bridge the top {P4VIV9(tart)7(H2O)4(OH)O23} and the bottom {P4VIV9(tart)6(H2O)9O22} layers via tartrate ligands and {PO4} tetrahedra, resulting in a 24-nuclearity POV skeleton structure. More interestingly, compound 1 serves as a heterogeneous catalyst for the selective oxidation of diphenylmethanes with 96.2% conversion and 93.6% selectivity under the optimized conditions.
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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-ß-AsW9O33)4]·93H2O (1) and Na2H19[AsRuIII2W11O20(OH)2(H2O)6(RuIIICl3)(B-ß-AsW9O33)6]·90H2O (2), were successfully self-assembled. The H2 evolution rates of 1 and 2 under optimal conditions were 3578.75 and 3027.69 µmol h-1 g-1 with TONs of 255 and 205, respectively. The stability of 1 was demonstrated by a series of characterizations. Besides, a possible photocatalytic mechanism was proposed.
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Two 48-nuclei silver nanocages with similar structures and compositions were synthesized by using Keggin-type polyoxometalates (POMs) BW12 and SiW11Ni as 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.
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Two two-dimensional Ln-substituted prazine dicarboxylic acid-functionalized selenotungstates Na3H9[(H2N(CH3)2]2{(Se4W27O100)[Ln4(H2O)8(Hpzdc)2(pzdc)]}·26H2O [Ln = Nd (1) and Ce (2)]; H2pzdc = 2,3-pyrazine dicarboxylic acid) have been synthesized by one-pot self-assembly strategy, in which the basic polyanion [Se4W27O100]22-was composed of two [SeW8O31]10- fragments, a [SeW9O33]8- segment and an intriguing {SeO} group, simultaneously tetra-nuclear Ln3+ ions with H2pzdc pendants were embedded. Compounds 1 and 2 showed excellent catalytic oxidation of thioether properties within a short time (20 min) with high 100% conversion and 98.9% selectivity. In addition, the pioneering Ln-substituted selenotungstates were used as catalysts to degrade sulfur mustard simulant 2-chloroethyl ethyl sulfide at room temperature with 99% conversion and 100% selectivity. The chemical kinetic experiment studies revealed that the catalytic reaction was in compliance with the first-order reaction, and the kinetic half-life (t1/2) values were 3.814 and 3.849 min, respectively.
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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)4 and 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)4 as linkers. As expected, the activities of the four POMOFs for the photocatalytic oxidative coupling of benzylamine were better than that of Rh2(OAc)4 or 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-SiW12 as 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)4 and POMs.