Polyoxometalate

About: Polyoxometalate is a research topic. Over the lifetime, 3493 publications have been published within this topic receiving 94123 citations. The topic is also known as: POM.

An ionothermal synthetic approach to porous polyoxometalate-based metal-organic frameworks.

Abstract: Porous materials with regular, bulky, accessible cages and channels have aroused great research interest owing to their potential applications in gas storage, separation, ionexchange, and heterogeneous catalysis. 2] Polyoxometalates (POMs), as a unique class of metal oxide clusters, constitute promising building units for targeting multifunctional materials because of their nanosize, adjustable compositions, abundant topologies, and their oxygen-rich surface with strong coordination abilities. 4] Despite the unparalleled success in the preparation of microporous/mesoporous compounds by covalently linking simple metal ions and organic ligands, attempts to prepare porous POM-based metal– organic frameworks have met with only limited success. Therefore, the synthesis of such frameworks is one of the most challenging issues in synthetic chemistry. Normally, porous materials are prepared by conventional solution synthesis and hydroor solvothermal synthesis. Solvents of these systems have been largely restricted to water and traditional organic solvents, such as methanol, acetonitrile, and acetone. It is undeniable that these solvents have some intrinsic disadvantages: for example, regarding synthesis, their lower boiling points have limited the use of higher temperatures out of safety concerns; furthermore, from the environmental perspective, volatile organic solvents have caused serious health and environmental problems. Therefore, it is very necessary to explore a more effective and environmentally friendly synthetic method to overcome these existing shortcomings. Ionic liquids (ILs), composed of cations and anions, have gained attention owing to their low melting points, high ionic conductivity, non-volatility, nonflammability, high polarity, low toxicity, zero vapor pressure, and relatively low viscosity. Therefore, they may be environmentally friendly alternatives to the traditional solvents. Ionothermal synthesis, with the use of an IL as solvent and structural directing agent, has already been comprehensively discussed in several detailed reviews, and has been successfully applied in the synthesis of zeolites or microporous solids. The remarkable work of Pakhomova and others have also proved the feasibility of such ionothermal methods for preparation of non-porous POM-based materials. Inspired by these recent developments, we present herein the extension of the ionothermal method to the realm of POM-based porous frameworks and demonstrate its capacity to produce such crystalline solids. To our knowledge, no reliable design of POM-based porous materials from this approach has yet been reported to date. In planning the synthesis, we chose a readily available ionic liquid, 1-ethyl-3-methylimidazolium bromide ([Emim]Br) as solvent, the weak coordinating ability of which can facilitate the self-assembly of the polyoxoanions. Meanwhile, to surmount the major obstacle in construction of POM-based solids with extra-large pores, bulky tetrabutylammonium bromide was used. On one hand, it could increase the aperture when it acts as a counterion filling in the cavity; on the other hand, subsequent ion exchange of it with smaller cations would recover the porosity effectively. Indeed, by slightly varying the experimental conditions, three porous POM-based 3D structures have been obtained based on the above design strategy: (TBA)2[Cu (BBTZ)2(xMo8O26)] (x = b for 1, x = a for 2 and 3) (TBA = tetrabutylammonium cation, BBTZ = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene). Single-crystal X-ray diffraction analysis reveals that the octamolybdate anion in 1 adopts the structural feature of the b-isomer, which consists of eight edge-shared MoO6 octahedra. Each [b-Mo8O26] 4 unit is covalently linked to two [CuBBTZ4] fragments through terminal oxo groups of octahedral Mo sites with Cu O distances of 2.302(4) and 2.302(4) . Each Cu cation adopts an octahedral geometry, defined by four N atoms from four BBTZ organic ligands (Cu1 N5 2.022(5), Cu1 N6 2.036(5)), and two O atoms from the [b-Mo8O26] 4 unit. The BBTZ ligands coordinated to the Cu center adopt a U-type configuration, and thus the CuBBTZ4 fragment has a windmill-type configuration with the four included angles between the four BBTZ ligands coordinated to the Cu centers of 908 (Supporting Information, Figure S1). The Cu centers of the windmills are extended to a 3D covalent net through the [b-Mo8O26] 4 units and the BBTZ ligands. The structure of 1 is very open, and contains three-directional channel systems. These channels intersect with each other and run along three different directions: 1.20 1.20 nm along the [100] direction, and 1.20 1.37 nm along the [011] and [0 11] directions, as shown in Figure 1a. From the topological view, the 3D architecture of 1 can be [*] Dr. H. Fu, Prof. C. Qin, Prof. Y. Lu, Dr. Z.-M. Zhang, Prof. Y.-G. Li, Prof. Z.-M. Su, Dr. W.-L. Li, Prof. E.-B. Wang Key Laboratory of Polyoxometalate Science of Ministry of Education Department of Chemistry, Northeast Normal University Changchun, Jilin 130024 (China) E-mail: qinc703@nenu.edu.cn wangeb889@nenu.edu.cn

Chiral polyoxometalate-induced enantiomerically 3D architectures: a new route for synthesis of high-dimensional chiral compounds.

Abstract: Two new enantiomerically chiral 3D architectures, l-(Zn(H2O)3)3[MnMo9O32]·4H2O and d-(Zn(H2O)3)3[MnMo9O32]·4H2O, have been produced from a new way. The compounds were composed of the discrete chiral [MnMo9O32]6- polyoxoanions linked by zinc(II) atoms to a 3D framework with a 2-fold interpenetrating net, which is the first examples of POM-based chiral 3D frameworks consisting of only inorganic components.

Design and synthesis of polyoxometalate-framework materials from cluster precursors

Abstract: Inorganic oxide materials are used in semiconductor electronics, ion exchange, catalysis, coatings, gas sensors and as separation materials. Although their synthesis is well understood, the scope for new materials is reduced because of the stability limits imposed by high-temperature processing and top-down synthetic approaches. In this Review, we describe the derivatization of polyoxometalate (POM) clusters, which enables their assembly into a range of frameworks by use of organic or inorganic linkers. Additionally, bottom-up synthetic approaches can be used to make metal oxide framework materials, and the features of the molecular POM precursors are retained in these structures. Highly robust all-inorganic frameworks can be made using metal-ion linkers, which combine molecular synthetic control without the need for organic components. The resulting frameworks have high stability, and high catalytic, photochemical and electrochemical activity. Conceptually, these inorganic oxide materials bridge the gap between zeolites and metal–organic frameworks (MOFs) and establish a new class of all-inorganic POM frameworks that can be designed using topological and reactivity principles similar to MOFs. Inorganic oxide materials are used in semiconductor electronics, ion exchange, catalysis, coatings, gas sensors and as separation materials. In this Review, we explain how polyoxometalate clusters are amenable to molecular control and can be assembled into inorganic frameworks owing to the molecular nature of their building blocks.

Sensitive and selective determination of aqueous triclosan based on gold nanoparticles on polyoxometalate/reduced graphene oxide nanohybrid

Abstract: Correction for ‘Sensitive and selective determination of aqueous triclosan based on gold nanoparticles on polyoxometalate/reduced graphene oxide nanohybrid’ by Mehmet Lutfi Yola et al., RSC Adv., 2015, 5, 65953–65962.