Science Journals RSS Feeds
Sponsored Links
Recent Comments

    Chemistry General

    Herein, we report on the first synthesis and structural characterization of the iron based aminoborane complexes [Fe(PNP)(H)(η2:η2‐H2B=NR2)]+ (R = H, Me). These species are formed upon protonation of the borohydride complex [Fe(PNP)(H)(η2‐BH4)] by ammonium salts [NH2R2]+ (R = H, Me). For R = Me, the reaction proceeds via the cationic dinuclear intermediate [{Fe(PNP)(H)}2(μ2,η2:η2‐BH4)]+. A mechanism for the reaction is proposed on the basis of DFT calculations that also indicate the final aminoborane complex as the thermodynamic product. All complexes were characterized by NMR spectroscopy, HRMS and X‐ray crystallography. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    The second case of linear end‐on and evidence for an unprecedented bridging end‐on coordination mode of CO2 have been discovered for vanadium aryloxide complexes of the rigid ligand system (ONNO)2‐ (ONNO = 2,4‐Me2‐2‐(OH)C6H2CH2]2 N(CH2)2NMe2). The reaction of divalent (ONNNO)V(TMEDA) with CO2 and under the appropriate reaction conditions affords the trivalent (ONNO)VIII(OH)(η1‐CO2)(2) resulting from an intermediate CO2 deoxygenation pathway followed by H‐atom abstraction from the aromatic solvent, and CO2 fixation. Instead, the reduction of trivalent (ONNO)VCl(THF) with K, followed by exposure to CO2 in ethereal solvent, afforded the dinuclear [(ONNO)V]2 (μ,η1‐CO2) (6). [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Charge doping is an effective way to induce metal‐insulate transition (MIT) in correlated materials for many important utilizations, which is however practically limited by problem of low stability. In this study, we have demonstrated a novel electron‐proton co‐doping mechanism to achieve pronounced phase modulation of monoclinic vanadium dioxide (VO2) at room temperature. Using L‐ascorbic acid (AA) solution to treat VO2, the ionized AA‐ species donate electrons to the adsorbed VO2 surface. Charges then electrostatically attract surrounding protons to penetrate, and eventually results in stable hydrogen‐doped metallic VO2. The variations of electronic structures, especially the electron occupancy of V‐3d/O‐2p hybrid orbitals, were examined by synchrotron characterizations and first‐principle theoretical simulations. Importantly, the adsorbed molecules protect hydrogen dopants from escaping out of lattice and thereby stabilize the metallic phase for VO2. Such an electron‐proton co‐doping mechanism driven by suitable molecules absorption would open a new door for engineering correlated oxide materials. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Ben-Gurion University of the Negev (BGU) researchers have developed a new chip device that offers superior identification of miniscule blood residues for forensic applications. [...]
    Mon, Jul 22, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Illumination consumes more than 20 percent of electricity. Thus, finding an efficient, stable, single-phase warm white-light material is very important. Lead hybrid perovskites have drawn interest for excellent photoelectric performance and simple synthesis. Lead perovskites with white-light emission have been studied, but photoluminescence quantum efficiencies (PLQEs) are low. However, the large-scale application of lead perovskites is hindered by toxicity and instability. Therefore, the substitution of Pb with less toxic or non-toxic elements and the replacement of organic cations with relatively stable inorganic cations is being investigated. [...]
    Mon, Jul 22, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Strong emissive solid‐state materials are mandatory components for a broad range of applications in emerging optoelectronic technologies. While many synthetic colorants show great promise from their molecular perspective, they often lose their appreciable properties in the solid state due to strong molecular interactions, which render them useless. The design of new organic pigments, which retain their desired optical properties although high tendency to crystallize, could enable to overcome such limitations. Here we show a new emissive material with monomer‐like absorption and emission profiles as well as fluorescence quantum yields >90% in its crystalline solid state. Inspired by natural pigments, a bright emitting solid‐state material and microcrystals thereof were accomplished by the attachment of two bulky tris(4‐tert‐butylphenyl)phenoxy substituents at the perylene bisimide bay positions. These substituents direct a packing arrangement with full enwrapping of the chromophore and unidirectional chromophore alignment within the crystal lattice to afford optical properties, which resemble natural pigment counterparts where chromophores are rigidly‐embedded in protein environments. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Although sodium ion batteries (SIBs) possess many beneficial features, their rate performance, cycling stability and safety need improvement for commercial applications. Basing on the mechanisms for the storage of sodium ions in carbon material, herein we present a multiple active sites decorated amorphous carbon (MAC) with rich structural defects and heteroatom doping as anode material for SIBs. The utilization of fast bonding‐debonding processes between sodium ions and the active sites could lead to a novel strategy to achieve superior sodium storage properties. Consequently, after materials characterization and electrochemical evaluation, the as‐prepared electrode could deliver high rate and long‐life performance. This active sites related design could be extended to other types of electrode materials thereby contributing to future SIBs practical applications. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    An operationally simple protocol to affect an atom transfer radical addition of commercially available ICH2Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in a one‐pot process into the corresponding cyclopropane upon treatment with a fluoride source. This method is highly selective for the cyclopropanation of unactivated terminal alkenes over non‐terminal alkenes and electron deficient alkenes. Due to the mildness of the procedure, a wide range of functional groups such as esters, amides, alcohols, ketones, and vinylic cyclopropanes are well tolerated. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    A remarkable enhancement of Raman scattering is achieved by submicron‐sized spherical ZnO superstructures. The secondary superstructures of ZnO particles with a uniform diameter in the range of 220–490 nm was formed by aggregating ~13 nm primary single crystallites. By engineering the superstructure size to induce Mie resonances, leading to an electromagnetic contribution to the SERS enhancement. Meanwhile, a highly efficient charge‐transfer (CT) contribution derived from the primary structure of the ZnO nanocrystallites was able to enhance the SERS signals as well. The highest Raman enhancement factor of 105 was achieved for a non‐resonant molecule by the synergistic effect of CT and Mie resonances. The Mie resonances scattered near‐field effect investigated in the present study provides not only an important guide for designing novel SERS‐active semiconductor substrates, but also a coherent framework for modelling the electromagnetic mechanism of SERS on semiconductors. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Liquid biopsy has the potential to replace invasive, painful and costly tissue biopsies in cancer diagnosis and management. Circulating tumour nucleic acids (ctNAs) are released from tumours cells and can be detected in blood samples, providing a way to track tumors without requiring a tissue sample. The detection of mutant ctNA sequences linked to cancer, however, requires a very sensitive and specific approach to detect relatively low amounts of mutant sequences, because they are masked by the presence of high levels of wild‐type sequences in patient samples. This review discusses a range of high‐performance nucleic acid biosensors capable of ctNA analysis in patient samples. We compare sequencing‐ and amplification‐based methods to next‐generation sensors for ctDNA and ctRNA (including miRNA) profiling, such as electrochemical methods, surface plasmon resonance, Raman spectroscopy, and microfluidics and dielectrophoresis‐based assays. We further present an overview of the analytical sensitivity and accuracy of these methods as well as biological and technical challenges they present. [...]
    Mon, Jul 22, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Sponsored Links
    Archives

    Copyright © 2013. All Rights Reserved.