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    Chemistry

    Angewandte Chemie Cover
    Journal of the American Chemical Society

    People with symptoms of Alzheimer's disease (AD), such as cognitive difficulties, behavior changes and mood swings, may wait months or even years to get a definitive diagnosis. That's because doctors lack a simple, accurate and inexpensive test for it. But according to an article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, researchers are getting much closer to developing the elusive blood test for AD. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Scientists at Rutgers and universities in Russia, Poland and England have solved a nearly 30-year mystery—how the molecular machinery works in an enzyme that makes a potent antibiotic. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Routes to making life-saving medications and other pharmaceutical compounds are among the most carefully protected trade secrets in global industry. Building on recent work programming computers to identify synthetic pathways leading to pharmaceutically complex molecules, researchers in Poland and South Korea have unveiled computerized methods to suggest only synthetic strategies that bypass patent-protected aspects of essential drugs. Their work appears January 17 in the journal Chem. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Scientists at Newcastle University have developed a biological system which lets cells form a desired shape by moulding their surrounding material—in the first instance creating a self-curving cornea. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Liver-on-a-chip cell culture devices are attractive biomimetic models in drug discovery, toxicology and tissue engineering research. To maintain specific liver cell functions on a chip in the lab, adequate cell types and culture conditions must be met, which includes 3D cell orientation and a consistent supply of nutrients and oxygen. Compared with conventional 2D cell culture techniques, organ-on-a-chip devices offer versatility and effective biomimicry suited for advanced applications in drug discovery and medicine. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Electronegativity is one of the most well-known models for explaining why chemical reactions occur. Now, Martin Rahm from Chalmers University of Technology, Sweden, has redefined the concept with a new, more comprehensive scale. His work, undertaken with colleagues including a Nobel Prize-winner, has been published in the Journal of the American Chemical Society. [...]
    Thu, Jan 17, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    The anology of the reactivity of group 1 phosphides to that of FLPs is further demonstrated by reactions with CO, affording a new synthetic route to acyl‐phosphide anions. The reaction of [K(18‐crown‐6)][PtBu2] 1 with CO affords [(18‐crown‐6)K•THF2][E‐tBuP=C(tBu)O] 2•THF2 as the major product, with the minor product, [K6(18‐crown‐6)][(tBu2PCO)2]3 3. Species 2 reacts with BPh3 or additional CO to give [K(18‐crown‐6)][(Ph3B)tBuPC(tBu)O] 4 and [K(18‐crown‐6)][(OCtBu)2P] 5, respectively. The acyl‐phosphide anion 2 is thought to be formed via a photochemically induced radical process involving a transient species with triplet carbene character, prompting 1,2‐tert‐butyl group migration. A similar process is proposed for the subsequent reaction of 2 with CO to give 5. [...]
    Wed, Jan 16, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Angewandte Chemie International Edition A Facile Route to Nonlinear Optical Materials: Three‐Site Aliovalent Substitution Involving One Cation and Two Anions
    Trading places: Two new nonlinear optical materials, α‐ and β‐Ba2[GaF4(IO3)2](IO3) (1 and 2), were designed via three‐site aliovalent substitution of VO4F2 in α‐ and β‐Ba2[VO2F2(IO3)2](IO3) by GaO2F4. The new materials display large second‐harmonic generation responses (≈6×KH2PO4 (KDP)), wide energy band gaps (4.61 and 4.35 eV), and high laser damage thresholds (29.7× and 28.3× relative to that of AgGaS2). Abstract Two mixed‐metal gallium iodate fluorides, namely, α‐ and β‐Ba2[GaF4(IO3)2](IO3) (1 and 2), have been designed by the aliovalent substitutions of α‐ and β‐Ba2[VO2F2(IO3)2](IO3) (3 and 4) involving one cationic and two anionic sites. Both 1 and 2 display large second‐harmonic generation responses (≈6×KH2PO4 (KDP)), large energy band gaps (4.61 and 4.35 eV), wide transmittance ranges (≈0.27–12.5 μm), and high relevant laser‐induced damage thresholds (29.7× and 28.3×AgGaS2, respectively), which indicates that 1 and 2 are potential second‐order nonlinear optical materials in the ultraviolet to mid‐infrared. Our studies propose that three‐site aliovalent substitution is a facile route for the discovery of good NLO materials. [...]
    Wed, Jan 16, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Angewandte Chemie International Edition Access to N‐Substituted 2‐Pyridones by Catalytic Intermolecular Dearomatization and 1,4‐Acyl Transfer
    When the fearless Don Quixote was charging at windmills, he left his slow companion, Sancho Panza, behind. In their Communication (DOI: 10.1002/anie.201812937), J. Sun et al. describe a novel rhodium‐catalyzed dearomatization and rearrangement of O‐substituted pyridines to access N‐substituted 2‐pyridones, a challenging target since their straightforward synthesis by simple alkylation of 2‐pyridones is thwarted by their preferred O‐reactivity. The key to this transformation is the formation of the pyridinium ylide and subsequent 1,4‐acyl migratory rearrangement. [...]
    Wed, Jan 16, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Angewandte Chemie International Edition Helicoidal Patterning of Nanorods with Polymer Ligands
    Gold nanorods, end‐grafted with achiral polymer ligands, show a new mechanism of chiral surface patterning giving a helicoidal morphology. This morphology is dictated by the relationship between the polymer grafting density and the ratio of the polymer length to the nanorod radius. Abstract Chiral packing of ligands on the surface of nanoparticles (NPs) is of fundamental and practical importance, as it determines how NPs interact with each other and with the molecular world. Herein, for gold nanorods (NRs) capped with end‐grafted nonchiral polymer ligands, we show a new mechanism of chiral surface patterning. Under poor solvency conditions, a smooth polymer layer segregates into helicoidally organized surface‐pinned micelles (patches). The helicoidal morphology is dictated by the polymer grafting density and the ratio of the polymer ligand length to nanorod radius. Outside this specific parameter space, a range of polymer surface structures was observed, including random, shish‐kebab, and hybrid patches, as well as a smooth polymer layer. We characterize polymer surface morphology by theoretical and experimental state diagrams. The helicoidally organized polymer patches on the NR surface can be used as a template for the helicoidal organization of other NPs, masked synthesis on the NR surface, as well as the exploration of new NP self‐assembly modes. [...]
    Wed, Jan 16, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL

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