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Hiroyuki Hayashi, Shota Katayama, Takahiro Komura, Yoyo Hinuma, Tomoyasu Yokoyama, Ko Mibu, Fumiyasu Oba, Isao Tanaka
Daylight-driven photocatalysts have attracted much attention in the context of "green" technology. Although various active materials have been reported and their applications are rapidly increasing, many are discovered after enormous experimental efforts. Herein the discovery of a novel oxide photocatalyst, β-SnMoO4, is demonstrated via a rational search of 3483 known and hypothetical compounds with various compositions and structures over the whole range of SnO-MO q/2 (M: Ti, Zr, and Hf (q = 4); V, Nb, and Ta (q = 5); Cr, Mo, and W (q = 6)) pseudobinary systems...
January 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Javier Fernández Sanjulián, Madhu Chennabasappa, Susana García-Martín, Gwilherm Nénert, Alain Wattiaux, Etienne Gaudin, Olivier Toulemonde
SrFe0.25Co0.75O2.63 was synthesized by a solid-state reaction. Its structural study at room temperature using conventional X-ray as well as neutron powder diffraction, electron diffraction and high-resolution transmission electron microscopy is presented. An oxygen-vacancy ordering related to the "314" model known for the Sr3Y1Co4O10.5 oxide is proposed despite neither an A-site ordering nor an A-site mismatch. By means of Mössbauer spectroscopy, Mohr salt titration and the difference in the neutron cross sections of Fe and Co, a cation distribution within the crystallographic sites as the following Sr4(Fe0...
January 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Spencer C Peck, Chen Wang, Laura M K Dassama, Bo Zhang, Yisong Guo, Lauren J Rajakovich, J Martin Bollinger, Carsten Krebs, Wilfred A van der Donk
Activation of O-H bonds by inorganic metal-oxo complexes has been documented, but no cognate enzymatic process is known. Our mechanistic analysis of 2-hydroxyethylphosphonate dioxygenase (HEPD), which cleaves the C1-C2 bond of its substrate to afford hydroxymethylphosphonate on the biosynthetic pathway to the commercial herbicide phosphinothricin, uncovered an example of such an O-H-bond-cleavage event. Stopped-flow UV-visible absorption and freeze-quench Mössbauer experiments identified a transient iron(IV)-oxo (ferryl) complex...
January 16, 2017: Journal of the American Chemical Society
Madhumita Dalal, Ayan Mallick, Jean-Marc Greneche, Dipankar Das, Pabitra K Chakrabarti
Nanocrystalline samples of Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 (NZCCF) are prepared by a simple co-precipitation method. To obtain nanoparticles of different sizes, the as prepared sample is annealed at 400, 600, 800 and 1000 °C. Nanoparticles of the sample annealed at 600 °C are encapsulated in multi-walled carbon nanotubes (MWCNT). To confirm the crystallographic phase, x-ray diffraction (XRD) patterns are analyzed by the Rietveld method and cation distribution in A- and B-sites is estimated from the analysis. Occupancy of Zn(2+) ions in A-site and that of Fe(3+) ions in B-site increase with the increase of annealing temperature (T A) and lattice parameters lie within 8...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Xiao Ma, Chen-Sheng Lin, Xiao-Quan Zhu, Sheng-Min Hu, Tian-Lu Sheng, Xin-Tao Wu
The heterometallic complexes trans-[Cp(dppe)FeNCRu(o-bpy)CNFe(dppe)Cp][PF6 ]n (1[PF6 ]n , n=2, 3, 4; o-bpy=1,2-bis(2,2'-bipyridyl-6-yl)ethane, dppe=1,2-bis(diphenylphosphino)ethane, Cp=1,3-cyclopentadiene) in three distinct states have been synthesized and fully characterized. 1(3+) [PF6 ]3 and 1(4+) [PF6 ]4 are the one- and two-electron oxidation products of 1(2+) [PF6 ]2 , respectively. The investigated results suggest that 1[PF6 ]3 is a Class II mixed valence compound. 1[PF6 ]4 after a thermal treatment at 400 K shows an unusually delocalized mixed valence state of [Fe(III) -NC-Ru(III) -CN-Fe(II) ], which is induced by electron transfer from the central Ru(II) to the terminal Fe(III) in 1[PF6 ]4 , which was confirmed by IR spectroscopy, magnetic data, and EPR and Mössbauer spectroscopy...
January 12, 2017: Angewandte Chemie
Yi-Fei Deng, Tian Han, Wei Xue, Naoaki Hayashi, Hiroshi Kageyama, Yan-Zhen Zheng
One-dimensional spin chains featuring strong axial anisotropic magnetism are promising candidates for isolatable and miniatured information storage materials, the so-called single-chain magnets (SCMs). Here we show a mixed azido/carboxylato bridged metamagnetic iron(ii) chain [Fe(N3)2(4-mpc)]n (4-mpc = N-methylpyridinium-4-carboxylate) with a large energy barrier of 150 K, a large remnant magnetization (1.55Nβ) and coercivity (1.7 T at 2 K) for homo-spin SCMs. Heat capacity and Mössbauer spectroscopy studies corroborate the intrinsic nature of SCM behavior regardless of weak interchain magnetic interactions, which lead to the coexistence of metamagnetism but not long-range magnetic ordering...
January 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Ragnar Bjornsson, Frank Neese, Serena DeBeer
Despite decades of research, the structure-activity relationship of nitrogenase is still not understood. Only recently was the full molecular structure of the FeMo cofactor (FeMoco) revealed, but the charge and metal oxidation states of FeMoco have been controversial. With the recent identification of the interstitial atom as a carbide and the more recent revised oxidation-state assignment of the molybdenum atom as Mo(III), here we revisit the Mössbauer properties of FeMoco. By a detailed error analysis of density functional theory-computed isomer shifts and computing isomer shifts relative to the P-cluster, we find that only the charge of [MoFe7S9C](1-) fits the experimental data...
January 10, 2017: Inorganic Chemistry
Susana García-Martín, Keisuke Manabe, Esteban Urones-Garrote, David Ávila-Brande, Noriya Ichikawa, Yuichi Shimakawa
Perovskite-related GdBaMnFeO5 and the corresponding oxidized phase GdBaMnFeO6, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO5 increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+. Determination of the crystal structure of both GdBaMnFeO5 and GdBaMnFeO6 is carried out at atomic resolution by means of a combination of advanced transmission electron microscopy techniques...
January 9, 2017: Inorganic Chemistry
Yuriy V Zatsikha, Cole D Holstrom, Kullapa Chanawanno, Allen J Osinski, Christopher J Ziegler, Victor N Nemykin
The 1,3,7,9-tetraferrocenylazadipyrromethene (3) and the corresponding 1,3,5,7-tetraferrocene aza-BODIPY (4) were prepared via three and four synthetic steps, respectively, starting from ferrocenecarbaldehyde using the chalcone-type synthetic methodology. The novel tetra-iron compounds have ferrocene groups directly attached to both the α- and the β-pyrrolic positions, and the shortest Fe-Fe distance determined by X-ray crystallography for 3 was found to be ∼6.98 Å. These new compounds were characterized by UV-vis, nuclear magnetic resonance, and high-resolution electrospray ionization mass spectrometry methods, while metal-metal couplings in these systems were probed by electro- and spectroelectrochemistry, chemical oxidations, and Mössbauer spectroscopy...
January 5, 2017: Inorganic Chemistry
Dmitry Batuk, Maria Batuk, Dmitry S Filimonov, Konstantin V Zakharov, Olga S Volkova, Alexander N Vasiliev, Oleg A Tyablikov, Joke Hadermann, Artem M Abakumov
The Bi3n+1Ti7Fe3n-3O9n+11 materials are built of (001)p plane-parallel perovskite blocks with a thickness of n (Ti,Fe)O6 octahedra, separated by periodic translational interfaces. The interfaces are based on anatase-like chains of edge-sharing (Ti,Fe)O6 octahedra. Together with the octahedra of the perovskite blocks, they create S-shaped tunnels stabilized by lone pair Bi(3+) cations. In this work, the structure of the n = 4-6 Bi3n+1Ti7Fe3n-3O9n+11 homologues is analyzed in detail using advanced transmission electron microscopy, powder X-ray diffraction, and Mössbauer spectroscopy...
December 23, 2016: Inorganic Chemistry
Ang Zhou, Jai Prakash, Gregory T Rohde, Johannes E M N Klein, Scott T Kleespies, Apparao Draksharapu, Ruixi Fan, Yisong Guo, Christopher J Cramer, Lawrence Que
Tetramethylcyclam (TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) exhibits two faces in supporting an oxoiron(IV) moiety, as exemplified by the prototypical [(TMC)Fe(IV)(Oanti)(NCCH3)](OTf)2, where anti indicates that the O atom is located on the face opposite all four methyl groups, and the recently reported syn isomer [(TMC)Fe(IV)(Osyn)(OTf)](OTf). The ability to access two isomers of [(TMC)Fe(IV)(Oanti/syn)] raises the fundamental question of how ligand topology can affect the properties of the metal center...
January 3, 2017: Inorganic Chemistry
Florian Strauss, Gwenaëlle Rousse, Moulay Tahar Sougrati, Daniel Alves Dalla Corte, Matthieu Courty, Robert Dominko, Jean-Marie Tarascon
In the search for new cathode materials for sodium ion batteries, the exploration of polyanionic compounds has led to attractive candidates in terms of high redox potential and cycling stability. Herein we report the synthesis of the two new sodium transition-metal pentaborates Na3MB5O10 (M = Fe, Co), where Na3FeB5O10 represents the first sodium iron borate reported at present. By means of synchrotron X-ray diffraction, we reveal a layered structure consisting of pentaborate B5O10 groups connected through M(2+) in tetrahedral coordination, providing possible three-dimensional Na-ion migration pathways...
December 19, 2016: Inorganic Chemistry
Soshi Iimura, Yudai Tomota, Satoru Matsuishi, Ryo Masuda, Makoto Seto, Haruhiro Hiraka, Kazutaka Ikeda, Toshiya Otomo, Hideo Hosono
The positively charged cage framework of the natural mineral mayenite, which enables various species with negative charge to be stabilized, is one of the key structures to provide the new functionalities exploited in applications. Here we report the structural and magnetic properties of recently found eltyubyuite, Ca12Fe10Si4O32Cl6, which is the first compound bearing a transition metal oxide as a main constituent in the mayenite-type structure. From neutron powder diffraction measurements at T = 20 K and the low temperature Mössbauer measurement, we determined the magnetic structure of eltyubyuite to be a ferrimagnet with oppositely aligned magnetic moments of +3...
January 3, 2017: Inorganic Chemistry
David W Mulder, Yisong Guo, Michael W Ratzloff, Paul W King
Hydrogenases couple electrochemical potential to the reversible chemical transformation of H2 and protons, yet the reaction mechanism and composition of intermediates are not fully understood. In this Communication we describe the biophysical properties of a hydride-bound state (Hhyd) of the [FeFe]-hydrogenase from Chlamydomonas reinhardtii. The catalytic H-cluster of [FeFe]-hydrogenase consists of a [4Fe-4S] subcluster ([4Fe-4S]H) linked by a cysteine thiol to an azadithiolate-bridged 2Fe subcluster ([2Fe]H) with CO and CN(-) ligands...
December 21, 2016: Journal of the American Chemical Society
Sandrine Gomes, Amandeep Kaur, Jean-Marc Grenèche, Jean-Marie Nedelec, Guillaume Renaudin
: Biphasic calcium phosphates (BCPs) are bioceramics composed of hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and beta-Tricalcium Phosphate (β-TCP, Ca3(PO4)2). Because their chemical and mineral composition closely resembles that of the mineral component of bone, they are potentially interesting candidates for bone repair surgery, and doping can advantageously be used to improve their biological behavior. However, it is important to describe the doping mechanism of BCP thoroughly in order to be able to master its synthesis and then to fully appraise the benefit of the doping process...
December 10, 2016: Acta Biomaterialia
Timothy H Yosca, Matthew C Langston, Courtney M Krest, Elizabeth L Onderko, Tyler L Grove, Jovan Livada, Michael T Green
We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential...
December 14, 2016: Journal of the American Chemical Society
Evgen V Govor, Karrar Al-Ameed, Indranil Chakraborty, Carla S Coste, Olena Govor, Yiannis Sanakis, John E McGrady, Raphael G Raptis
One-electron reduction of a pyrazolate-bridged triangular Fe3 (μ3 -O) core induces a cascade wherein all three metal centers switch from high-spin Fe(3+) to low-spin Fe(2.66+) . This hypothesis is supported by spectroscopic data ((1) H-NMR, UV-vis-NIR, infra-red, (57) Fe-Mössbauer, EPR), X-ray crystallographic characterization of the cluster in both oxidation states and also density functional theory. The reduction induces substantial contraction in all bond lengths around the metal centers, along with diagnostic shifts in the spectroscopic parameters...
January 9, 2017: Angewandte Chemie
Weizhao Yin, Lizhi Huang, Emil Bjerglund Pedersen, Cathrine Frandsen, Hans Christian B Hansen
Layered Fe(II)-Fe(III) hydroxides (green rusts, GRs) are efficient reducing agents against oxidizing contaminants such as chromate, nitrate, selenite, and nitroaromatic compounds and chlorinated solvents. In this study, we adopted a buffered precipitation approach where glycine (GLY) was used in the synthesis of sulfate-interlayered GR (GRSO4) by aerial oxidation of Fe(II) or co-precipitation by adding Fe(III) salt to an aqueous solution of Fe(II) at constant pH. In both the oxidation and the co-precipitation methods pure crystalline GRSO4 was precipitated in the presence of 70mM GLY (pH 8...
November 22, 2016: Journal of Colloid and Interface Science
Guoyin Shen, Ho Kwang Mao
Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields...
January 2017: Reports on Progress in Physics
Magdalena Kaczmarska, Dominika Żydek, Justyna Wilkłacz-Potoczny, Maria Fornal, Tomasz Grodzicki, Elżbieta Kochowska, Krzysztof Kozak, Łukasz Gocal, Władysław Pohorecki, Krzysztof Matlak, Józef Korecki, Květoslava Burda
Our aim was to study the influence of low doses (0.2-4 μGy) of α radiation on the stability of human erythrocytes isolated from healthy and diabetic erythrocytes. Absorption spectroscopy was used to measure the level of red blood cell (RBC) hemolysis, along with Mössbauer spectroscopy, which is a highly specific method suited to monitoring various hemoglobin forms. States of hemoglobin are sensitive to a homeostatic imbalance in red blood cells. Changes in the membrane skeleton organization of irradiated erythrocytes isolated from healthy donors were studied using atomic force microscopy (AFM)...
January 2017: Microscopy Research and Technique
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