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Chemistry: a European Journal

Philippe Schollhammer, Federica Arrigoni, Salma Mohamed Bouh, Catherine Elleouet, François Pétillon, Luca De Gioia, Giuseppe Zampella
Electrochemical oxidation of the complex [Fe2(CO)4(κ2-dmpe)(µ-adtBn)] (adtBn = (SCH2)2NCH2C6H5, dmpe = Me2PCH2CH2PMe2) (1) has been studied by cyclic voltammetry (CV) in acetonitrile and in dichloromethane in presence of various substrates L (L =MeCN, trimethylphosphite, isocyanide). The oxidized species, [1-MeCN](PF6)2, [1-(P(OMe)3)2](PF6)2 and [1-(RNC)4](PF6)2 (R = tButyl, Xylyl), have been prepared and characterized by IR, NMR spectroscopies and, excepted [1-MeCN](PF6)2, by X-ray diffraction analysis. The crystallographic structures of the new FeIIFeII complexes reveal in any case that the association of one additional ligand (P(OMe)3 or RNC) occurs and, according to the nature of the substrates, further substitutions of one or three carbonyl groups, by P(OMe)3 or RNC, respectively, arise...
July 16, 2018: Chemistry: a European Journal
Thomas C Stephens, Aggie Lawer, Thomas French, William Paul Unsworth
Macrocyclic lactones can be prepared from lactams and hydroxyacid derivatives via an efficient 3- or 4-atom iterative ring expansion protocol. The products can also be expanded using amino acid-based linear fragments, meaning that macrocycles with precise sequences of hydroxy- and amino acids can be assembled in high yields by 'growing' them from smaller rings, using a simple procedure in which high dilution is not required. The method should significantly expedite the practical synthesis of diverse nitrogen containing macrolide frameworks...
July 16, 2018: Chemistry: a European Journal
G Naaresh Reddy, Rakesh Parida, Arindam Chakraborty, Santanab Giri
Zintl ions are of a special type of naked anionic cluster mainly consists of group 13, 14 and 15 elements in the periodic table. Due to the presence of multiple negative ions, the chemistry of Zintl ions are unique. Not only they are forming Zintl phase with alkali and alkaline earth metals but also forming different organo-Zintl cluster with different properties. Using first principle calculation based on density functional theory we have designed a new deltahedral Organo-Zintl cluster with Ge94- as core and aromatic heterocyclic compounds as ligands...
July 16, 2018: Chemistry: a European Journal
Dario Braga, Simone d'Agostino, Luca Fornasari, Fabrizia Grepioni, Federica Rossi, Michele Chierotti, Roberto Gobetto
The order-disorder phase transition associated with the uprise of reorientational motion in (DABCOH2)2+, in the supramolecular salts of general formula [1∙(DABCOH2)]X2 (where 1 = 12-crown-4, DABCO = 1,4-diazabicyclo[2.2.2]octane, and X = Cl- or Br-), has been investigated by variable temperature X-ray diffraction on single crystals and powder samples, as well as by DSC and solid state NMR spectroscopy. The two compounds undergo a reversible phase change at 292 and 290 K, respectively. The two crystalline materials form solid solutions [1∙(DABCOH2)]Cl2xBr2(1-x) in the whole composition range (0 < x <1), with a decrease in the temperature of transition to a minimum of ca 280 K corresponding to x = 0...
July 16, 2018: Chemistry: a European Journal
Thomas Neil Snaddon, W Rush Scaggs
Cooperation between Lewis base and Pd catalysts enables the direct enantioselective α-functionalization of aryl and vinyl acetic acid esters using a bifunctional B(pin)-substituted electrophile. Critical to the success of this method was the recognition that both catalysts could control the necessary stereochemical aspects; the Lewis base catalyst controls the enantioselectivity of the reaction, while the Pd catalyst regulates alkenylB(pin) configuration. This is the first example of using cooperative catalysis to control both stereochemical features during Pd-catalyzed allylic alkylation...
July 16, 2018: Chemistry: a European Journal
William McCulloch, Neng Xiao, Gerald Gourdin, Yiying Wu
Rechargeable superoxide (O₂¯) batteries have the potential to surpass current lithium-ion technology due to their high theoretical energy densities. The use of superoxide as an energy storage material is highly advantageous when compared to their close relative, peroxide. This is due to enhanced reversibility of the 1-electron redox process. To efficiently stabilize superoxide, larger metal cations are required such as sodium and potassium. Therefore, the two most studied systems are sodium and potassium oxygen batteries...
July 16, 2018: Chemistry: a European Journal
Yuhui Hua, Qing Lan, Jiawei Fei, Chun Tang, Jianfeng Lin, Hexukun Zha, Shiyan Chen, Yinghua Lu, Jiangxi Chen, Xumin He, Haiping Xia
Bulky substituents play important roles in controlling the reaction pathways or producing selected products. We reported that the shift of metallafuran rings in a metallapentalenofuran complex can be promoted by the substituent effect via a reversible C-H bond reductive elimination and oxidative addition. The starting osmapentalyne, a so-called 7-carbon carbolong complex, was produced by the oxidation of a metallapentalenofuran with FeCl₃. It was then allowed to react with nucleophiles, followed by a C-H activation, to give the aforementioned metallapentalenofuran complex...
July 16, 2018: Chemistry: a European Journal
Sophie Carenco, Cecile S Bonifacio, Judith C Yang
Bimetallic nanoparticles are widely studied, for example in catalysis. However, possible restructuring in the environment of use, such as segregation or alloying, may occur. Taken individually, state-of-the-art analytical tools fail to give an overall picture of these transformations. This study combines an ensemble analysis (near-ambient-pressure X-ray photoelectron spectroscopy) with a local analysis (environmental transmission electron microscopy) to provide an in situ description of the restructuring of core-shell nickel-cobalt nanoparticles exposed to cycles of reduction and oxidation...
July 16, 2018: Chemistry: a European Journal
Natalia Mateu, Sarah L Kidd, Leen Kalash, Hannah F Sore, Andrew Madin, Andreas Bender, David R Spring
N-containing quaternary stereocenters represent important motifs in medicinal chemistry. However, due to their inherently sterically hindered nature, they remain underrepresented in small molecule screening collections. As such, the development of synthetic routes to generate small molecules that incorporate this particular feature are highly desirable. Herein, we describe the diversity-oriented synthesis (DOS) of a diverse collection of structurally distinct small molecules featuring this three-dimensional (3D) motif...
July 16, 2018: Chemistry: a European Journal
Janis Fricke, Claudius Lenz, Jonas Wick, Felix Blei, Dirk Hoffmeister
The fungal genus Psilocybe and other genera comprise numerous mushroom species that biosynthesize psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine). It represents the prodrug to its dephosphorylated psychotropic analog, psilocin. The colloquial term "magic mushrooms" for these fungi alludes to their hallucinogenic effects and to their use as recreational drug. However, clinical trials have recognized psilocybin as a valuable candidate to be developed into a medication against depression and anxiety...
July 16, 2018: Chemistry: a European Journal
Bruno Michel Ameduri
An overview on the synthesis, properties, and applications of fluoropolymers (PFs) is presented. First, a non-exhaustive summary on the homopolymers from conventional radical polymerization of fluoromonomers is proposed. FPs are interesting materials thanks to their outstanding properties such as thermal, oxidative and chemical resistances, low dissipation factor, refractive index, permittivity, and water absorptivity, as well as excellent durability and weatherability. Various strategies of synthesis are proposed, especially on recent studies on radical (co)polymerization of fluoroalkenes, just like their properties and applications ranging from coatings and energy related-materials (e...
July 16, 2018: Chemistry: a European Journal
Huishan Shang, Qiumei Di, Muwei Ji, Bing Bai, Jiajia Liu, Wenxing Chen, Meng Xu, Hongpan Rong, Jia Liu, Jiatao Zhang
Focusing on ternary I-III-VI2 colloidal nanocrystals synthesis with precise control of composition (from doping to ternary composition) and NIR fluorescence performance, monodisperse binary In3+ doped Ag2S NCs and Ternary AgInS2 NCs have been achieved successfully by facile low temperature in-situ conversion of colloidal Ag2S nanoparticles. Here, In3+ ions are inserted into the crystal lattice of Ag2S NCs at relative low temperature as dopant following phase transition to be ternary AgInS2 NCs at relative high temperature...
July 16, 2018: Chemistry: a European Journal
Valeria Lanzilotto, Jose Luis Silva, Teng Zhang, Matuš Stredansky, Cesare Grazioli, Konstantin Simonov, Erika Giangrisostomi, Ruslan Ovsyannikov, Monica de Simone, Marcello Coreno, Carlos Moyses Araujo, Barbara Brena, Carla Puglia
We have investigated the effect of intermolecular H-bonding interactions on the local electronic structure of N-functionalities, amino group and pyridine-like N, which are characteristic of polymeric carbon nitrides materials, p-CN(H), a new class of metal-free organo-photo-catalysts. Specifically, we have performed a characterization of the melamine molecule, a building block of p-CN(H), combining X-ray photoelectron (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopies. The molecule has been studied in the gas phase, as non-interacting system, and in the solid state within a hydrogen bonded network...
July 15, 2018: Chemistry: a European Journal
Hong Wang, Lifeng Wang, Liancheng Wang, Zheng Xing, Xuan Wu, Wei Zhao, Xiujun Qi, Zhicheng Ju, Quanchao Zhuang
Early studies indicate that graphite is feasible as a negative electrode of the potassium ion battery while its electrochemical performance still cannot meet the application demand. More efforts should focus on increasing the specific capacity and improve superior rate capability in the meantime. As an attempt, we utilize a stainless steel autoclave technology to make the phosphorus nanoparticles encapsulated in the reduced graphene oxide matrix as the electrode materials for potassium ion battery. As a result, the composite matrix affords high reversible capacity of 354 mAh g-1 and 253 mAh g-1 at 100 mA g-1 and 500 mA g-1, respectively...
July 14, 2018: Chemistry: a European Journal
Xinbo Zhang
Sodium-organic batteries, which use organics as electrode materials for sodium ion batteries, are an attractive alternative to conventional lithium ion batteries for the next-generation sustainable and versatile energy storage devices due to the abundant sodium resources and environmental friendly organics. However, organics used in sodium ion batteries also encounter some issues such as low redox potential, high-solubility in electrolyte and low conductivity. In response, altering the aromatic system/attaching electron withdrawing groups, constructing polymer and incorporating conductive matrix are effective strategies...
July 14, 2018: Chemistry: a European Journal
Hyeongjoo Choi, Yongwon Jung
Multivalent interactions between more than one interconnected biomolecule are easily found in diverse natural systems. With cooperation of many interacting pairs, this clustered binding can achieve highly enhanced affinities. While the binding of an individual pair remains reversible, the binding between multivalent biomolecules can become nearly irreversible. Although the underlying principles of the multivalent effect have yet to be revealed, this intriguing concept of multivalent interaction has been widely applied to diverse fields...
July 14, 2018: Chemistry: a European Journal
Xiaoyu Ren, Marcel Wesolek, Pierre Braunstein
Tritopic NCNHCN' ligands containing a central N-heterocyclic carbene (NHC) donor flanked by two chemically-different nitrogen donors (Nimine and Namine) are evaluated as potential tridentate pincer-type ligands in NiII complexes. The imidazolium chloride [(ImH){C(Me)=NDipp}(C2NMe2)]Cl (1) and the ammonium-imidazolium dichlorides [(ImH){C(Me)=NDipp}(C2NHMe2)]Cl2 (4) and [(ImH){C(Me)=NDipp}(C3NHMe2)]Cl2 (5), differing by the length (C2 or C3) of the alkyl spacer were used as precursors. Oxidative-addition of 1 to [Ni(cod)2] afforded the dinuclear bis-NHC NiII complex [Ni2Cl2{µ-C(Me)=NDipp-κ2Nimine,C}{μ-Im(C2NMe2)-κ3Namine,CNHC,Nimid}{Im[C(Me)=NDipp](C2NMe2)-κ1CNHC}] (2) resulting from partial ligand rearrangement...
July 14, 2018: Chemistry: a European Journal
Tharwat Mohy El Dine, Omar Sadek, Emmanuel Gras, David Perrin
The Balz-Schiemann reaction endures as a method for the preparation of (hetero)aryl fluorides yet is eschewed due to the need for harsh conditions or high temperatures along with the need to isolate potentially explosive diazonium salts. In a departure from these conditions, we show that various organotrifluoroborates (RBF3-s) may serve as fluoride ion sources for solution-phase fluoro-dediazoniation in organic solvents under mild conditions. This methodology was successfully extended to a one-pot process obviating aryl diazonium salt isolation...
July 13, 2018: Chemistry: a European Journal
Alistair Groves, Jose I Martínez, Joshua J Smith, Hon Wai Lam
Metal migration through a carbon chain is a versatile method for achieving remote functionalization. However, almost all known examples involve the overall net migration of alkylmetal species. Here, we report that allylrhodium species obtained from hydrorhodation of 1,3-dienes undergo chain walking toward esters, amides, or (hetero)arenes over distances of up to eight methylene units. The final, more highly conjugated allylrhodium species undergo nucleophilic allylation with aldehydes and an imine to give Z-homoallylic alcohols and amines, respectively...
July 13, 2018: Chemistry: a European Journal
Matthew M D Roy, Shiori Fujimori, Michael J Ferguson, Robert McDonald, Norihiro Tokitoh, Eric Rivard
We report the introduction of the labile trimethylsiloxy group to Ge(II) centers in the presence of an N-heterocyclic carbene donor. The new complex IPr*GeCl(OSiMe₃) (IPr = [(HCNDipp)₂C:]; Dipp = 2,6-iPr₂C₆H₃) was readily converted into the structurally unique Ge(II) siloxyhydrido-germylene IPr*GeH(OSiMe₃)*BH₃ by treatment with lithium borohydride. Additionally, the reactive siloxygermylene cation [IPr*Ge(OSiMe₃)]⁺ was synthesized and clean oxidative addition of CH₂Cl₂ was demonstrated...
July 13, 2018: Chemistry: a European Journal
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