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Andrea Koschinsky, Luise Heinrich, Klaus Boehnke, J Christopher Cohrs, Till Markus, Maor Shani, Pradeep Singh, Karen Smith Stegen, Welf Werner
Deep-sea mining refers to the retrieval of marine mineral resources such as manganese nodules, ferromanganese crusts and seafloor massive sulfide deposits, which contain a variety of metals that serve as crucial raw materials for a range of applications, from electronic devices to renewable energy technologies to construction materials. With the intent of decreasing dependence on imports, supporting the economy and potentially even overcoming the environmental problems related to conventional terrestrial mining, a number of public and private institutions have re-discovered their interest in exploring the prospects of deep-sea mining, which had been deemed economically and technically unfeasible in the early 1980 s...
June 19, 2018: Integrated Environmental Assessment and Management
Carles Fuertes-Espinosa, Alejandra Gómez-Torres, Roser Morales-Martínez, Antonio Rodríguez-Fortea, Cristina García-Simón, Felipe Gándara, Inhar Imaz, Judith Juanhuix, Daniel Maspoch, Josep M Poblet, Luis Echegoyen, Xavi Ribas
Supramolecular nanocapsule 1·(BArF)8 is able to sequentially and selectively entrap recently discovered U2@C80 and unprecedented Sc2CU@C80, simply by soaking crystals of 1·(BArF)8 in a toluene solution of arc-produced soot. These species, selectively and stepwise absorbed by 1·(BArF)8, are easily released, obtaining highly pure fractions of U2@C80 and Sc2CU@C80 in one step. Sc2CU@C80 represents the first example of a mixed metal actinide-based endohedral metallofullerene (EMF). Remarkably, the host-guest studies revealed that 1·(BArF)8 is able to discriminate EMFs with the same carbon cage but with different encapsulated cluster and computational studies provide support for these observations...
June 19, 2018: Angewandte Chemie
Manfred Karras, Michał Dąbrowski, Radek Pohl, Jiří Rybáček, Jaroslav Vacek, Lucie Bednárová, Karol Grela, Ivo Starý, Irena G Stará, Bernd Schmidt
Helical chirality is a novel enantioselectivity inducing element in transition metal catalyzed transformations. The principle is illustrated herein for the example of asymmetric olefin metathesis. We describe the synthesis of the first helically chiral Ru-NHC alkylidene complex from an aminohelicene-derived imidazolium salt, which was ligated to the first generation Hoveyda-Grubbs catalyst. Kinetic data were aquired for benchmark test reactions and compared to an achiral catalyst. The helically chiral Ru-catalyst was evaluated in asymmetric RCM and ROM/CM reactions, which proceeded with promising levels of enantioselectivity...
June 19, 2018: Chemistry: a European Journal
Luisa Stelter, Thomas Teusch, Jens Bielefeld, Sven Doye, Thorsten Klüner
The alpha-alkylation of amines with alkenes catalyzed by early transition metal complexes represents an efficient and atom economic method for the synthesis of functionalized amines from simple and easily available starting materials. While the successful use of secondary amines, such as dimethylamine, strongly underlines the enormous industrial potential of this reaction, the analogous intermolecular alpha-alkylation of primary amines, especially methylamine, remains an unsolved synthetic task to this day...
June 19, 2018: Chemistry: a European Journal
Nabeel Azeem, Stephanie M Skaudis, Stuart K Amateau
No abstract text is available yet for this article.
May 2018: VideoGIE: an official video journal of the American Society for Gastrointestinal Endoscopy
Jérôme Cuny, Nathalie Tarrat, Fernand Spiegelman, Arthur Huguenot, Mathias Rapacioli
Density-functional based tight-binding (DFTB) is an efficient quantum mechanical method that can describe a variety of systems, going from organic and inorganic compounds to metallic and hybrid materials. The present topical review addresses the ability and performance of DFTB to investigate energetic, structural, spectroscopic and dynamical properties of gold and silver materials. After a brief overview of the theoretical basis of DFTB, its parametrization and its transferability, we report its past and recent applications to gold and silver systems, including small clusters, nanoparticles, bulks and surfaces, bare and interacting with various organic and inorganic compounds...
June 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jian Yuan, Yanyu Liu, Ping Wu, Wei Zhou
The effects of hole doping and strain on the electronic and magnetic properties of single layered TiO2 nanosheet were investigated here. It is found that the spontaneous magnetism can be introduced in all systems doped with low valence metal, indicating hole is the key fact to trigger local magnetic moments. Especially, a half-metal magnetism takes place when Li substitutes a Ti atom. As for the stability of dopants, Al doping case shows lower formation energy than those of Li and Mg doping under O-rich conditions...
June 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Danbi Lee, Gibaek Lee, Yongsug Tak
Aluminum-ion batteries are considered to be a promising post lithium-ion battery system in energy storage devices because aluminum is earth-abundant, has a high theoretical capacity, and is of low cost. We report on the chemical activities and stabilities of chloroaluminate anions [Al<sub>n</sub>Cl<sub>n+1</sub>]<sup>‒</sup> with aluminum metal using a different mole ratio of AlCl<sub>3</sub> and 1-ethyl-3-methylimidazolium chloride...
June 19, 2018: Nanotechnology
Deborah Queiroz Freitas, Rocharles Cavalcante Fontenele, Eduarda Helena Leandro Nascimento, Taruska Ventorini Vasconcelos, Marcel Noujeim
AIM: To evaluate the influence of kilovoltage (kVp) and metal artefact reduction tool (MAR) on the magnitude of cone beam computed tomography (CBCT) artifacts. METHODS: A titanium and zirconia implants were inserted alternately in a posterior region of a mandible. CBCT exams were acquired with ProMax 3D (Planmeca Oy, Helsinki, Finland) and Picasso Trio machines (Vatech, Hwaseong, South Korea) using 70 kVp, 80 kVp and 90 kVp with and without MAR activation. The other exposure factors remained fixed at 5mA, FOV 80 × 50 mm and voxel 0...
June 19, 2018: Dento Maxillo Facial Radiology
Hui Xu, Pingping Song, Jin Wang, Yukou Du
Well-defined noble metal nanomaterials are attractive as catalysts for various applications due to abundant surface active sites. However, the shape-controlled synthesis of high-performance Pt-based nanocatalysts remains a forbidden challenge. We herein demonstrate a versatile approach for realizing the systemically controlled syntheses of bimetallic Pt-Cu nanocrystals from concave nanocubes (CNCs), to excavated nanocubes (ENCs), to tripods (TRPs) via simply switching the amount of glycine (reducing agent)...
June 19, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Alexander N Koronatov, Nikolai V Rostovskii, Alexander F Khlebnikov, Mikhail Sergeevich Novikov
High yield synthesis of 1,2-dihydropyrimidines by Rh(II)-catalyzed reaction of diazocarbonyl compounds with 1,4-di- and 1,4,5-trisubstituted pyrazoles is reported. This reaction represents the first example of a carbenoid insertion into an N-N bond and provides a novel approach to 4-unsubstituted 1,2-dihydropyrimidines with a broad range of functional group tolerance. According to DFT calculations the pyrazole ring expansion proceeds via the sequential formation of the metal-bound pyrazolium ylide, metal-free pyrazolium ylide and 1,5-diazahexatriene followed by 1,6-cyclization...
June 19, 2018: Journal of Organic Chemistry
Arjan Geersing, Nathalie Ségaud, Monique G P van der Wijst, Marianne G Rots, Gerard Roelfes
Metal coordination complexes can display interesting biological activity, as illustrated by the bleomycins (BLMs), a family of natural antibiotics that when coordinated to a redox-active metal ion, show antitumor activity. Yet, which metal ion is required for the activity in cells is still subject to debate. In this study, we described how different metal ions affect the intracellular behavior and activity of the synthetic BLM-mimic N, N-bis(2-pyridylmethyl)- N-bis(2-pyridyl)methylamine (N4Py). Our study shows that a mixture of iron(II), copper(II), and zinc(II) complexes can be generated when N4Py is added to cell cultures but that the metal ion can also be exchanged by other metal ions present in cells...
June 19, 2018: Inorganic Chemistry
Guanhui Zhao, Yaoguang Wang, Xiaojian Li, Xue Dong, Huan Wang, Bin Du, Wei Cao, Qin Wei
This work describes a sandwich-type electrochemiluminescence (ECL) strategy for insulin detection by using Ru(bpy)32+ as luminophore which was encapsulated in UiO-67 metal-organic framework (UiO-67/Ru(bpy)32+). Since UiO-67 possesses the characteristics of large specific surface area and porosity, more Ru(bpy)32+ could be loaded onto its surface and holes, thus greatly improving the electrochemiluminescence efficiency. Furthermore, the ECL resonance energy transfer (ECL-RET) could occur between UiO-67/Ru(bpy)32+ (ECL donor) and Au@SiO2 nanoparticles (ECL acceptor), resulting in conspicuously decreased of ECL response...
June 19, 2018: ACS Applied Materials & Interfaces
Xiaomei Wang, Guoxun Ji, Cen Shi, Juan Diwu, Lanhua Chen, Daxiang Gui, Jianmei Wan, Mark A Silver, Jianqiang Wang, Shuao Wang
Deferiprone (3-hydroxy-1,2-dimethyl-4(1H)-pyridone, DFP), which is a drug clinically used for removing heavy metals in vivo, was explored for its removal efficiency towards uranium. The reaction of uranyl nitrate hexahydrate with DFP at room temperature yielded the compound [(UO2)(H2O)(C7NO2H8)2]·4H2O (1), which crystallizes from a mixed solution of methanol and water (pH = 7.0). X-ray diffraction shows that the stable complexation of uranyl occurs from the coordination of two bidentate DFP ligands perpendicular to the O[double bond, length as m-dash]U[double bond, length as m-dash]O unit with a fifth coordinating oxygen atom coming from one water molecule, resulting in a pentagonal bipyramidal geometry...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Jiří Pinkas, Róbert Gyepes, Ivana Císařová, Jiří Kubišta, Michal Horáček, NaděŽda Žilková, Karel Mach
Reactions following the addition of dihydrogen under maximum atmospheric pressure to bis(trimethylsilyl)acetylene (BTMSA) complexes of titanocenes, [(η5-C5H5-nMen)2Ti(η2-BTMSA)] (n = 0, 1, 3, and 4) (1A-1D), and zirconocenes, [(η5-C5H5-nMen)2Zr(η2-BTMSA)] (n = 2-5) (4A-4D), proceeded in diverse ways and, depending on the metal, afforded different products. The former complexes lost, in all cases, their BTMSA ligand via its hydrogenation to bis-1,2-(trimethylsilyl)ethane when reacted at 80 °C for a prolonged reaction time...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Elaheh Pousaneh, Marcus Korb, Volodymyr Dzhagan, Marcus Weber, Julian Noll, Michael Mehring, Dietrich R T Zahn, Stefan E Schulz, Heinrich Lang
The synthesis of ketoiminato copper(ii) complexes [Cu(OCRCHC(CH3)NCH2CH2X)(μ-OAc)]2 (X = NMe2: 4a, R = Me; 4b, R = Ph. X = OMe: 5, R = Me) and [Cu(OCRCHCMeNCH2CH2NEt2)(OAc)] (6, R = Me) from RC(O)CHC(CH3)N(H)CH2CH2X (X = NMe2: 1a, R = Me; 1b, R = Ph. X = NEt2: 1c, R = Me. X = OMe: 2, R = Me) and [Cu(OAc)2·H2O] (3) is reported. The molecular solid-state structures of 4-6 were determined by single crystal X-ray diffraction studies, showing that 4a,b and 5 are dimers which are set up by two [{Cu(μ-OAc)L}] (L = ketoiminato ligand) units featuring a square-planar Cu2O2 core with a distorted square-pyramidal geometry at Cu(ii)...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Malik Dilshad Khan, Ghulam Murtaza, Neerish Revaprasadu, Paul O'Brien
Xanthate complexes are used in the low temperature atom efficient synthesis of some geological and technologically important ternary compounds. The process involves direct heating of a stoichiometric mixture of the metal xanthate complexes. The reactive melts of the xanthates, generated in the transition state, cleanly decompose to ternary metal sulfides. The method has great potential for the facile scalable synthesis of ternary materials of composition ABX2 (such as AI = Ag, Cu; BIII = Bi, Cr, Fe, In, Sb and X = S) or AB2X4 (AII = Cd, Co, Cu, Ni; BIII = Co, Cr, Ni, Fe, and X = S)...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Gabriele Dalla Torre, Jon I Mujika, Elena Formoso, Eduard Matito, Maria J Ramos, Xabier Lopez
Due to aluminum's controversial role in neurotoxicity, the goal of chelation therapy, the removal of the toxic metal ion or attenuation of its toxicity by transforming it into less toxic compounds, has attracted considerable interest in the past years. In the present paper we present, validate and apply a state-of-the-art theoretical protocol suitable for the characterization of the interactions between a chelating agent and Al(iii). In particular, we employ a cluster-continuum approach based on Density Functional Theory calculations to evaluate the binding affinity of aluminum for a set of two important families of aromatic chelators: salicylic acids and catechols...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Wenguang Xi, Gang Yan, Huaqiao Tan, Liguang Xiao, Sihang Cheng, Shifa Ullah Khan, Yonghui Wang, Yangguang Li
Transition metal (TM) oxides and hydroxides are one of the important candidates for the development of durable and low-cost electrocatalysts towards water splitting. The key issue is exploring effective methods to improve their electrocatalytic activity. Herein, we report a new type of P-doped Ni(OH)2/NiMoO4 hierarchical nanosheet array (abbr. P-Ni(OH)2/NiMoO4) grown on Ni foam (NF), which can act as a highly efficient electrocatalyst towards overall water splitting. Such a composite was obtained by a three-step preparation process...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
S Spirkl, M Grzywa, D Volkmer
The synthesis and crystal structure of a novel metal organic framework, constructed from MnIII, the 4,4'-bipyrazolate (BPZ) ligand and bridging hydroxyl groups is presented in this work. The network topology is identical to M-CFA-6 (M = Fe, Ga), but in the case of Mn-CFA-6, the structure crystallizes in the monoclinic crystal system due to the Jahn-Teller effect of the high spin d4 manganese(iii) centers. Thermal treatment of Mn-CFA-6 leads to decomposition of the framework above 150 °C. The porosity of Mn-CFA-6 was measured by carbon dioxide sorption, since solvent exchange and removal of the occluded solvent molecules leads to a compression of the pores...
June 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
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