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Special Issue "New Functional Polyoxometalates: from Fundamental Aspects to Application"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 30 October 2018

Special Issue Editor

Guest Editor
Professor Tadaharu UEDA

Department of Marine Resource Science, Faculty of Agriculture and Marine Science, Kochi University, 200 Monobe-otsu, Nankoku 783-8502 Japan
E-Mail
Interests: synthesis and characterization of novel polyoxometalates; electrochemistry and analytical application of polyoxometalates; analysis for the formation mechanism of polyoxometalates

Special Issue Information

Dear Colleagues,

A huge number of polyoxometalates (POMs) have been prepared and characterized for ca. 200 years. POMs exhibit fascinating chemical properties and many of POMs have complicated structure to form beautiful molecule architecture. Therefore, POMs have been applied to versatile fields, such as catalysts, analytical chemistry and biochemistry and material chemistry. Although POMs are one family of inorganic clusters, organic molecule moiety attached POMs, ionic liquid-type POMs and other types inorganic-organic hybrid POMs have been prepared to exhibit unique chemical properties recently. The POMs chemistry is still promising research area and keeps spreading to wide range of scientific disciplines. This Special Issue focuses on the most recent advances in polyoxometalate-based material chemistry covering synthetic methods and application (perspectives) in catalysis, battery, fuel cell, magnetism, bio-medicine, sensor and other interesting areas. In addition, the detailed mechanistic and theoretical studies for chemical properties of POMs are included in this Special Issue.

Prof. Dr. Tadaharu UEDA
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Polyoxometalates
  • synthesis
  • characterization
  • hybrid material
  • catalysis
  • magnetism
  • electrochemistry

Published Papers (2 papers)

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Research

Open AccessArticle Keggin-Type Heteropoly Salts as Bifunctional Catalysts in Aerobic Baeyer-Villiger Oxidation
Materials 2018, 11(7), 1208; https://doi.org/10.3390/ma11071208
Received: 31 May 2018 / Revised: 2 July 2018 / Accepted: 9 July 2018 / Published: 13 July 2018
PDF Full-text (1102 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The cobalt, manganese, and iron salts of tungstophosphoric or molybdophosphoric acid with growing content of metals were applied for the first time as catalysts in the Baeyer-Villiger (BV) oxidation of cyclohexanone to ε-caprolactone with molecular oxygen. The catalysts were characterized with Fourier transform
[...] Read more.
The cobalt, manganese, and iron salts of tungstophosphoric or molybdophosphoric acid with growing content of metals were applied for the first time as catalysts in the Baeyer-Villiger (BV) oxidation of cyclohexanone to ε-caprolactone with molecular oxygen. The catalysts were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and ethanol decomposition reaction. Introduction of transition metals into the heteropoly structure increases the activity of resulting heteropoly salts in comparison with parent heteropolyacids. It was shown that the most active catalysts are salts of the heteropoly salts with one metal atom introduced and one proton left (HMPX) type, (where M = Co, Fe, Mn, and X = W, Mo) with the metal to proton ratio equal one. Among all of the studied catalysts, the highest catalytic activity was observed for HCoPW. The effect indicates that both the acidic and redox properties are required to achieve the best performance. The Baeyer-Villiger (BV) oxidation mechanism proposed identifies the participation of heteropoly compounds in three steps of the investigated reaction: oxidation of aldehyde to peracid (redox function), activation of carbonyl group (Lewis acidity), and decomposition of the Criegee adduct to ε-caprolactone (Brønsted acidity). Full article
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Open AccessArticle Proton-Enhanced Dielectric Properties of Polyoxometalates in Water under Radio-Frequency Electromagnetic Waves
Materials 2018, 11(7), 1202; https://doi.org/10.3390/ma11071202
Received: 4 June 2018 / Revised: 5 July 2018 / Accepted: 11 July 2018 / Published: 13 July 2018
PDF Full-text (4263 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Electromagnetic waves, such as microwaves, have been used to enhance various chemical reactions over polyoxometalates. The dielectric properties of catalysts are among the relevant parameters facilitating catalytic reactions under electromagnetic radiation. This study describes the dielectric properties of polyoxometalate catalysts in aqueous and
[...] Read more.
Electromagnetic waves, such as microwaves, have been used to enhance various chemical reactions over polyoxometalates. The dielectric properties of catalysts are among the relevant parameters facilitating catalytic reactions under electromagnetic radiation. This study describes the dielectric properties of polyoxometalate catalysts in aqueous and organic solutions to understand the mechanism of interactions between polyoxometalates and electromagnetic waves. Specific loss factors of polyoxometalates were observed at lower frequencies (<1 GHz) by the ionic conduction of the polyoxometalate solution. The evolution of ionic conduction depended strongly on cations rather than anions. Proton-type polyoxometalates exhibited significantly higher loss factors than other cations did. The activation energy for ionic conduction in protonated silicotungstic acid (H4SiW12O40) was significantly low in water (7.6–14.1 kJ/mol); therefore, the high loss factor of protonated polyoxometalates in water was attributed to the proton relay mechanism (i.e., Grotthuss mechanism). The results suggested that the proton relay mechanism at the radio-frequency band is critical for generating selective interactions of polyoxometalates with applied electromagnetic fields. Full article
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