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Huarui Wu, Lengwan Li, Masaki Tsuboi, Yongqiang Cheng, Weiyu Wang, Eugene Mamontov, Sayaka Uchida, Zhe Wang, Panchao Yin
Highly efficient proton conductors, polyoxometalate-poly(ethylene glycol) (POM-PEG) hybrid nanocomposites, have been synthesized by encapsulating single PEG chain inside the 1D nano-channel defined by the frameworks of POMs. By employing two types of neutron scattering techniques complemented by thermal analysis, we prove that in a nano-channel a single PEG chain stays as a distorted helix. More importantly, we reveal that the PEG segments perform a localized longitudinal random walk, and quantitatively show the strong correlation between the local motion of PEG and the macroscopic proton conduction of the material...
August 14, 2018: Journal of Physical Chemistry Letters
Lee Cronin, Masaaki Ohba, Keita Nakanishi, Geoffrey Cooper, Laurie Points, Leanne Bloor
Inorganic chemical cells (iCHELLs) are compartment structures consisting of polyoxometalates (POMs) and cations, offering structured and confined reaction spaces bounded by membranes. We have constructed a system capable of efficient anisotropic and hierarchical photo-induced electron transfer across the iCHELL membrane. Mimicking photosynthesis, our system uses proton gradients between the compartment and the bulk to drive efficient conversion of light into chemical energy, producing hydrogen upon irradiation...
August 13, 2018: Angewandte Chemie
Ya-Qian Lan, Xue-Li Zhai, Jiang Liu, Ling-Yun Hu, Jian-Chun Bao
Photocatalytic hydrogen evolution technology is recognized as a promising approach to relieve the growing energy crisis. Consequently, the development of stable photocatalyst with high-performance has always been the focus of research. In this work, quaternary composites involved in snowflake-like CdS nanocrystal wrapped with different amounts of polyoxometalate-decorated g-C3N4 and polypyrrole (GPP@CdS), were synthesized for hydrogen production under visible-light irradiation. It was revealed that the acquired best composite (40% GPP@CdS composite) exhibits hydrogen production activity of 1321 μmol and at least seven cycles with negligible activity loss, which exceeds that of the CdS more than 2 times...
August 10, 2018: Chemistry: a European Journal
Xin-Xiong Li, Lin-Jie Zhang, Cai-Yan Cui, Rui-Hu Wang, Guo-Yu Yang
Two unprecedented examples of cluster organic frameworks (TBA)3 Cu[V6 O13 (L)2 ]2 ·4DEF (2) (TBA)Ag[V6 O13 (L)2 ] solvent (3) (TBA = tetrabutylammonium, H3 L = tris(hydroxymethyl)-4-picoline, DEF = N, N'-diethylformamide) based on Lindqvist-type polyoxometalate (POM) secondary building units (SBUs) have been constructed successfully. Compounds 2 and 3 are the second cases of cluster organic frameworks based on Lindqvist-type POM cluster SBUs. Furthermore, the cluster organic framework of 2 exhibits efficient electrocatalytic activity and strong durability in oxygen reduction reaction...
August 10, 2018: Inorganic Chemistry
Tom Homewood, James T Frith, J Padmanabhan Vivek, Nieves Casañ-Pastor, Dino Tonti, John R Owen, Nuria Garcia-Araez
The Keggin-type polyoxometalate α-SiW12O404- increases the discharge capacity and potential of lithium-oxygen batteries, by facilitating the reduction of O2 to Li2O2, as confirmed by in situ electrochemical pressure measurements and XRD. Compared to organic redox mediators, polyoxometalates have higher chemical and structural stability, which could lead to longer cycling lithium-oxygen batteries.
August 10, 2018: Chemical Communications: Chem Comm
Chisato Kato, Ryo Machida, Rio Maruyama, Ryo Tsunashima, Xiao-Ming Ren, Mohamedally Kurmoo, Katsuya Inoue, Sadafumi Nishihara
Continual progress has been achieved in information technology through unrelenting miniaturisation of the single memory bit in integrated ferromagnetic, ferroelectric, optical, and related circuits. However, as miniaturisation is approaching its theoretical limit, new memory materials are being sought as replacements. Here, we report a unique material exhibiting single-molecule electric polarisation switching that can operate above room temperature. The phenomenon occurs in a Preyssler-type polyoxometalate (POM) cluster we call a single-molecule electret (SME), which exhibits all the characteristics of ferroelectricity but without long-range dipole ordering...
August 7, 2018: Angewandte Chemie
Wolfgang Bensch, Ulrike Warzok, Lisa Mahnke
Polyoxometalates (POMs) are an intriguing class of compounds due to their tremendous structural variety and the wide spectrum of resulting properties, which make them interesting for applications in fields such as catalysis, material science or nanotechnology. Their ability to form large supramolecular architectures by self-assembly offers an entry to complex, functional systems. After an introduction into the structure and synthesis of POMs of the early transition metals, we focus on recently discovered water soluble antimonato polyoxovanadates (Sb-POVs) and the investigation of their chemical reactivity...
August 6, 2018: Chemistry: a European Journal
Mercè Martin-Sabi, Joaquín Soriano-López, Ross S Winter, Jia-Jia Chen, Laia Vilà-Nadal, De-Liang Long, José Ramón Galán-Mascarós, Leroy Cronin
Water oxidation is a key reaction for the conversion of solar energy into chemical fuels, but effective water-oxidation catalysts are often based on rare and costly precious metals such as Pt, Ir or Ru. Developing strategies based on earth-abundant metals is important to explore critical aspects of this reaction, and to see whether different and more efficient applications are possible for energy systems. Herein, we present an approach to tuning a redox-active electrocatalyst based on the doping of molybdenum into the tungsten framework of [Co4 (H2 O)2 (PW9 O34 )2 ]10- , known as the Weakley sandwich...
March 8, 2018: Nature Catalysis
Chun-Guang Liu, Yun-Jie Chu
In the present paper, the reaction mechanism corresponding to activation of hydrogen peroxide (H2 O2 ) by a divanadium-substituted polyoxometalate (POM) [γ-PV2 W10 O38 (μ-OH)2 ]3- (I) to form catalytic active species, peroxo complex [γ-PV2 W10 O38 (μ-η2 ,η2 -O2 )]3- (III), was studied by using the density functional theory (DFT) calculations method with B3LYP functional. The results indicate that coordination of H2 O2 to I proceeds via a vanadium-center-assisted proton transfer pathway to remove the first water molecule and form a hydroperoxy intermediate [γ-PV2 W10 O38 (μ-OH) (μ-OOH)]3- (II)...
July 23, 2018: Journal of Molecular Graphics & Modelling
Yan Leng, Chenjun Zhang, Bing Liu, Miaomiao Liu, Pingping Jiang, Sheng Dai
Palladium nanoparticles (Pd NPs) anchored on a phosphotungstic acid-attached melem porous hybrid (PW/melem) are prepared by hybridization of phosphotungstic acid palladium salt and melem, followed by chemical reduction. PW/melem is demonstrated to be an outstanding support that can stabilize and disperse small Pd NPs (2 nm), and significantly boost their efficiency for H2 generation from dehydrogenation of formic acid (FA). Experimental results and mechanistic investigations indicate that a strong electron interaction exists between Pd NPs and the PW anions; the PW anions accept electrons from Pd first and, during FA dehydrogenation, the reduced blue PW donates electrons to Pd...
August 3, 2018: ChemSusChem
Haralampos N Miras, Laia Vilà-Nadal, Leroy Cronin
Correction for 'Polyoxometalate based open-frameworks (POM-OFs)' by Haralampos N. Miras et al., Chem. Soc. Rev., 2014, 43, 5679-5699.
August 1, 2018: Chemical Society Reviews
Fiona A Black, Aurélie Jacquart, Georgios Toupalas, Sandra Alves, Anna Proust, Ian P Clark, Elizabeth A Gibson, Guillaume Izzet
Controlled design of photoactive hybrids would provide highly active materials for solar energy conversion and photo(electro) catalysis. We describe the kinetics of photoinduced electron transfer in a series of photoactive hybrids based on Keggin-type polyoxometalates (POMs) covalently grafted to bodipy photosensitizers. We show how the electronic properties and corresponding dynamics of these hybrids can be readily tuned by varying the POM metal ion, the anchoring functionalization and the spacer length. Ultrafast visible and IR transient absorption spectroscopy, supported by spectroelectrochemical measurements, reveals that photoinduced electron transfer from the bodipy chromophore to the organosilyl POM derivative occurs as rapidly as τ = 54 ps to generate a long-lived ( τ = 4...
July 7, 2018: Chemical Science
Marisabel Mecca, Luigi Todaro, Maurizio D'Auria
The treatment of wood wastes of Castanea sativa L., Quercus frainetto , Larix decidua , and Paulownia tomentosa S. in autoclave in the presence of micrometric crystals of H₃PMo12 O40 showed an impressive increase of the amount of extractives. The extractives were mainly constituted of insoluble compounds that were analyzed by using gas chromatography-mass spectrometry (GC-MS) after acetylation. The GC-MS analysis of the chloroform soluble fraction of the extractives obtained from sativa showed the presence of methyl hexadecanoate and octadecanoic acid, that of the extractives of frainetto showed the presence of octadecanal and some long chain hydrocarbons...
July 28, 2018: Biomolecules
Valeria A Zamolo, Gloria Modugno, Elisa Lubian, Alessandro Cazzolaro, Fabrizio Mancin, Livia Giotta, Disma Mastrogiacomo, Ludovico Valli, Alessandra Saccani, Silke Krol, Marcella Bonchio, Mauro Carraro
The Keggin-type polyoxometalate [γ-SiW10 O36 ]8- was covalently modified to obtain a bis-biotinylated conjugate able to bind avidin. Spectroscopic studies such as UV-vis, fluorimetry, circular dichroism, coupled to surface plasmon resonance technique were used to highlight the unique interplay of supramolecular interactions between the homotetrameric protein and the bis-functionalized polyanion. In particular, the dual recognition mechanism of the avidin encompasses (i) a complementary electrostatic association between the anionic surface of the polyoxotungstate and each positively charged avidin subunit and (ii) specific host-guest interactions between each biotinylated arm and a corresponding pocket on the tetramer subunits...
2018: Frontiers in Chemistry
Yan Gao, Ziyan Lv, Ruimin Gao, Gai Zhang, Ying Zheng, Jianshe Zhao
Fuel desulfurization as a crucial subject has aroused people's attention with the environmental problems becoming more and more important. Oxidative desulfurization (ODS) is one of the most promising methods due to its high efficiency, low cost, easy operation and mild reaction condition. With the loading of polyoxometalate (POM), a hybrid material (CNTs@MOF-199) supported catalysts (CNTs@MOF-199-POM) are designed and prepared using one-pot procedure. The novel catalysts are investigated by FT-IR, XRD, XPS, SEM and BET...
July 6, 2018: Journal of Hazardous Materials
Rui Tian, Boyu Zhang, Mingming Zhao, Qiang Ma, Yanfei Qi
Polyoxometalates (POMs) have been proven to possess intrinsic peroxidase-like activity. However, by far, most of POMs with intrinsic peroxidase-like activity are stable at acid aqueous. Herein, we firstly utilized Na10 [α-SiW9 O34 ] with the peroxidase-like property in basic pH condition to build a CdTe quantum dots (QDs)-based fluorometric method for detection of hydrogen peroxide. In the CdTe QDs stable pH value, Na10 [α-SiW9 O34 ] can catalyze the decomposition of H2 O2 into·OH radicals that could efficiently quench the fluorescence of CdTe QDs...
October 1, 2018: Talanta
Adrica Kyndiah, Abduleziz Ablat, Seymour Guyot-Reeb, Thorsten Schultz, Fengshuo Zu, Norbert Koch, Patrick Amsalem, Stefano Chiodini, Tugbahan Yilmaz Alic, Yasemin Topal, Mahmut Kus, Lionel Hirsch, Sophie Fasquel, Mamatimin Abbas
Multiple functionality of tungsten polyoxometalate (POM) has been achieved applying it as interfacial layer for solution processed high performance In2 O3 thin film transistors, which results in overall improvement of device performance. This approach not only reduces off-current of the device by more than two orders of magnitude, but also leads to a threshold voltage reduction, as well as significantly enhances the mobility through facilitated charge injection from the electrode to the active layer. Such a mechanism has been elucidated through morphological and spectroscopic studies...
July 19, 2018: Scientific Reports
Neha Thakur, Subhasis Das Adhikary, Mukesh Kumar, Daisy Mehta, Anil K Padhan, Debaprasad Mandal, Tharamani C Nagaiah
A novel sandwich polyoxometalate (POM) Na12 [WCo3 (H2 O)2 (CoW9 O34 )2 ] and poly(vinylimidazolium) cation [PVIM+ ] in combination with nitrogen-doped carbon nanotubes (NCNTs) was developed for a highly selective and ultrasensitive detection of dopamine. Conductively efficient heterogenization of Co5 POM catalyst by PVIM over NCNTs provides the synergy between PVIM-POM catalyst and NCNTs as a conductive support which enhances the electron transport at the electrode/electrolyte interface and eliminates the interference of ascorbic acid (AA) at physiological pH (7...
March 31, 2018: ACS Omega
Ali Harchani, Monika Kučeráková, Michal Dušek, Amor Haddad
We report a complex study on the crystal structures, electronic properties, reactivity and dynamics of three polyoxometalate compounds (C6NH8)4[H2P2Mo5O23]·5H2O (1), (C2H8N)5[HP2Mo5O23]·(C3H9NO2)0.5·(H2O)1.5 (2) and (C2H8N)3[PMo12O40]·(H2O)0.34 (3). These compounds were synthesized using a solution method and characterized by single-crystal X-ray diffraction. Crystallography confirmed three distinct symmetries P1[combining macron], P21/c and R3[combining macron]c for 1, 2, and 3, respectively, and unit cell constants a = 12...
July 18, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Shuxia Shang, Zhengguo Lin, Anxiang Yin, Song Yang, Yingnan Chi, Yin Wang, Jing Dong, Bing Liu, Ni Zhen, Craig L Hill, Changwen Hu
The generation of five types of Ln(III)-containing tungstotellurates(VI), dimeric (DMAH)12 Na2 [H10 (WO2 ){Ln(H2 O)5 (TeW18 O65 )}2 ]· nH2 O (abbreviated as {Ln2 Te2 W37 }; Ln = Eu, Gd, or Tb; DMAH = dimethylammonium), tetrameric (DMAH)21 Na7 [H16 {Ln(H2 O)5 (TeW18 O64 )}4 ]· nH2 O (abbreviated as {Ln4 Te4 W72 }, Ln = Eu or Gd), 2:2 dimeric (DMAH)12 [H6 {Tb(H2 O)3 (TeW17 O61 )}2 ]·25H2 O (abbreviated as {Tb2 Te2 W34 }), 1:1 monosubstituted (DMAH)7 Na2 [H2 Tb(H2 O)4 (TeW17 O61 )]·21H2 O (abbreviated as {TbTeW17 }), and three-dimensional polymer (DMAH)2 [HTb(H2 O)4 {TeW6 O24 }]·14H2 O (abbreviated as {TbTeW6 } n ), provides insight into the rich condensation chemistry of lacunary and other Dawson-type polyoxometalates...
August 6, 2018: Inorganic Chemistry
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