scispace - formally typeset
Search or ask a question
Topic

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.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the rhodium containing polyoxometalate, [(WZnRhIII2)(ZnW9O34)2]10− was prepared by reaction of rhCl3 with RhCl3.
Abstract: The rhodium containing polyoxometalate, [(WZnRhIII2)(ZnW9O34)2]10− was prepared by reaction of [(WZn3)(ZnW9O34)2]12− with RhCl3. The X-ray diffraction showed this compound to be isostructural to other compounds of this series. This was confirmed by the IR spectra. The elementary analysis and cyclic voltammetry measurements indicated that the polyoxometalate was of high purity. Epoxidation of alkenes with 30% aqueous H2O2 in 1,2-dichloroethane/water biphasic systems using [(WZnRhIII2)(ZnW9O34)2]10− as catalyst showed high overall activity as compared to other noble metal substituted polyoxometalates of this series. The reactions were highly selective to epoxidation of cyclohexene and similar to previously reported [(WZnMnII2)(ZnW9O34)2]12−, except that hydrogen peroxide yields were measurably higher in the rhodium case. The [(WZnRhIII2)(ZnW9O34)2]10− catalyst appears to be stable under turnovers conditions. Using IR spectroscopy as a probe to compare active polyoxometalates (Rh and Mn) versus an inactive one (Zn), showed that in the former case peroxo-tungstate intermediates could be identified whereas for the inactive compound no such intermediate was observed. A possible mechanism taking into account reactivity, steric constraints and IR spectra assuming structural integrity under catalytic turnover conditions was put forth.

62 citations

Journal ArticleDOI
TL;DR: In this paper, cyclic voltammetry (CV) and differential pulse voltameters (DPV) measurements of both [Cnmim]3[α-PW12O40] salts (for n=2 and 5) were performed in acetonitrile containing either tetra-n-butylammonium hexafluorophosphate, abbreviated TBAPF6, or the corresponding [C nmim]BF4 ionic liquids (ILs) as electrolytes.

62 citations

Journal ArticleDOI
TL;DR: The host-guest stabilization of the M6O192- species with M = Mo or W from aqueous solution using γ-cyclodextrin as trapping agent reveals remarkable hydrolytic stability that offers new opportunities for exploring potentialities of molybdates or tungstates in the field of biology and medicine, when combined to CDs as efficient drug carrier/delivery agents.
Abstract: Formation of one of the most representative polyoxometalate (POM) archetypes, namely the Lindqvist anion M6O192– with M = MoVI or WVI, was considered as elusive in aqueous solution. Herein, we report on the host–guest stabilization of the M6O192– species with M = Mo or W from aqueous solution using γ-cyclodextrin as trapping agent. The adduct {M6O19@γ-CD}2– reveals remarkable hydrolytic stability that offers new opportunities for exploring potentialities of molybdates or tungstates in the field of biology and medicine, when combined to CDs as efficient drug carrier/delivery agents.

62 citations

Journal ArticleDOI
TL;DR: It is found that the fourth endothermic peak is sensitive to the charges of the PMs, and the transition temperature decreases from 185, 177, to 164 degrees C with decreasing PM charges from 13, 11, to 9, respectively.
Abstract: We investigate in detail novel organic−inorganic hybrid liquid crystalline materials, the complexes of surfactant-encapsulated polyoxometalate clusters (SECs), using thermal, X-ray diffraction, and FT-IR spectroscopic analyses. The differential scanning calorimetry measurements reveal four phase transitions under heating processes. We employ FT-IR spectroscopy to understand these phase behaviors. On the basis of vibration spectral assignments, the evidence suggests that the first two phase transitions are associated with the increase of gauche conformers and the disruption of alkyl chains packing in the heating run; the third phase transition is due to the full conformational disorder of alkyl chains covered on the polyoxometalates (PMs); no significant C−H stretching or wagging vibrations are observed with the fourth transition. We find that the fourth endothermic peak is sensitive to the charges of the PMs, and the transition temperature decreases from 185, 177, to 164 °C with decreasing PM charges from...

62 citations

Journal ArticleDOI
TL;DR: In this article, the authors showed that the Krebs-type Fe polyoxotungstates can also catalyze the cyclohexane oxygenation with high turnover frequencies, and they showed that these Krebs types can also promote the oxidative cleavage of 3,5-ditert-butylcatechol with molecular oxygen.
Abstract: Transition metal substituted polyoxometalates (TMS-POM) provide a redox-active metal center, (Fe, Ru, Mn or else), with a totally inorganic ligand system, featuring rigid polydentate binding sites, high electron-acceptor character, extreme robustness and interesting structural and coordination properties, in some cases, mimicking the coordination geometry of natural oxygenase enzymes. Their synthesis and reactivity can be promoted by microwave (MW) induced dielectric heating. In particular, MW irradiation induces a very efficient and selective hydrothermal synthesis of the diamagnetic, air-stable [Ru II (DMSO)PW 11 O 39 ] 5− . Its catalytic activity has been screened with shunt oxidants like NaIO 4 and KHSO 5 and PyCl 2 NO. Under dioxygen and MW irradiation, [Ru II (DMSO)PW 11 O 39 ] 5− catalyzes the oxidation of DMSO to DMSO 2 in water. Fe III -POMs with nuclearities 1–4, namely [α-Fe(H 2 O)SiW 11 O 39 ] 5− (FeSiW 11 ), [γ-Fe 2 (H 2 O) 2 SiW 10 O 38 ] 6− (Fe 2 SiW 10 ) , [α-Fe 3 (H 2 O) 3 SiW 9 O 37 ] 7− (Fe 3 SiW 9 ) and [β-Fe 4 (H 2 O) 10 (XW 9 O 33 ) 2 ] n− (Fe 4 X 2 W 18 , X = Se IV , Te IV ; As III , Sb III ; n = 4, 6) were also found to catalyze the MW assisted cyclohexane oxygenation with high turnover frequencies. Preliminary results indicate that the Krebs-type Fe polyoxotungstates can also promote the oxidative cleavage of 3,5-ditert-butylcatechol with molecular oxygen.

62 citations


Network Information
Related Topics (5)
Catalysis
400.9K papers, 8.7M citations
91% related
Alkyl
223.5K papers, 2M citations
87% related
Photocatalysis
67K papers, 2.1M citations
87% related
Crystal structure
100.9K papers, 1.5M citations
87% related
Cyclic voltammetry
55.9K papers, 1.4M citations
87% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023246
2022566
2021213
2020218
2019187
2018216