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    Chemistry General

    Using "Trojan horses" to combat cancer from within the tumour cells themselves without damaging healthy tissues is the aim of this new tool created by researchers from the University of Granada (UGR), the Institute of Nanoscience of Aragon (INA), the University of Zaragoza, and the Cancer Research UK Edinburgh Centre at the University of Edinburgh. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Tracking the lateral position of single cells and particles plays an important role in evaluating the efficiency of microfluidic cell focusing, separation and sorting. Traditionally, the performance of microfluidic cell separation and sorting is evaluated either by analyzing the input and collected output samples requiring multiple steps of off-chip analysis or the use of expensive equipment (e.g., flow cytometry), or by detecting the lateral positions of cells using an expensive high-speed imaging setup with intricate image processing algorithms or laborious manual analysis. Hence, there is a great need to develop a simple approach for the lateral position measurement of flowing particles. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Multiple myeloma is a type of blood cancer in which malignant plasma cells, a type of white blood cell, accumulate in the bone marrow. This leads to bone destruction and failure of the marrow, which in healthy individuals, produce all the body's red blood cells. The most recent data from the American Cancer Society estimates that almost 27,000 new cases of MM are diagnosed every year, and of these, over 11,000 patients died. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Photoresponsive materials that degrade, expand, change shape, or alter their microscopic topology in response to light have been studied for a wide range of applications. Such materials are typically in a metastable state during irradiation and return to their pre‐irradiated state after removal of the light source. Strategies for the synthesis of materials that can reversibly photoswitch between two or more stable states, remaining in each state until a different stimulus is applied, could find applications as actuators, catalysts, and sensors. Here, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu 24 L 24 cuboctahedral metal‐organic cages/polyhedra (MOCs) decorated with coumarin ligands. Upon exposure to long‐wavelength UV light in the presence of a photosensitizer and a hydrogen donor, this “polyMOC” material can be reversibly switched between three oxidation states of copper (Cu(II), Cu(I), and Cu(0)). The instability of the MOC junctions of these materials in the Cu(I) and Cu(0) states leads to network disassembly, providing Cu(I)/Cu(0) solutions, respectively, that are stable until exposure to a second stimulus, oxygen, induces re‐oxidation to Cu(II) and rapid supramolecular gelation. This reversible supramolecular disassembly of the Cu‐based polyMOC network is shown to occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent double networks with spatiotemporally enhanced mechanical properties. This work demonstrates that reversible disassembly of multicomponent MOCs can be used to switch bulk material properties, enabling functions that are difficult to access in traditional supramolecular networks. [...]
    Tue, Nov 19, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Scientists from Trinity have created a suite of new biological sensors by chemically re-engineering pigments to act like tiny Venus flytraps. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    A fundamental question in biology is how cells orchestrate chemical reactions in time and space. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    To synthesize high-performance materials for organic photovoltaics (OPVs) that convert solar radiation into direct current, materials scientists must meaningfully establish the relationship between chemical structures and their photovoltaic properties. In a new study on Science Advances, Wenbo Sun and a team including researchers from the School of Energy and Power Engineering, School of Automation, Computer Science, Electrical Engineering and Green and Intelligent Technology, established a new database of more than 1,700 donor materials using existing literature reports. They used supervised learning with machine learning models to build structure-property relationships and fast screen OPV materials using a variety of inputs for different ML algorithms. [...]
    Tue, Nov 19, 2019
    Source: PhysOrg Chemistry Category: CHEMISTRY GENERAL
    Pd‐catalyzed sequences involving oxidative addition, cyclization, and termination through intermolecular nucleophile capture have tremendous utlity. Indeed, they can generate a plethora of different polycyclic structures possessing a diverse range of functionality. However, one area of deficiency for Pd(0)/Pd(II) variants is the ability to conclude them with oxygen‐based species. Inspired by the recent discovery of one such reaction in the course of a total synthesis program, we delineate herein that it has significant power, both in terms of substrate scope as well as the terminating oxygen nucleophile. As a result, the reaction proved critical in achieving total syntheses of two oxygenated natural products, one of which was prone to over‐oxidation. Finally, a mechanistic proposal that accounts for its success is provided. [...]
    Tue, Nov 19, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    A base‐catalyzed protocol that enables a stereoselective 1,1‐silaboration of terminal alkynes is described. This method does not only offer a new strategy to functionalize simple and readily accessible alkynes beyond 1,2‐difunctionalization events, but also provides an unconventional atom‐ and step‐economical approach to rapidly and reliably access versatile geminal silylboranes in the absence of transition metals with an exquisite stereoselectivity pattern [...]
    Tue, Nov 19, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
    Thiostrepton is a potent antibiotic against a broad range of Gram‐positive bacteria, but its medical applications have been limited by its poor aqueous solubility. In this work, the first C(sp2)–H amidation of dehydroalanine (Dha) residues was applied to the site selective modification of thiostrepton to prepare a variety of derivatives. Unlike all prior methods for the modification of thiostrepton, the alkene framework of the Dha residue is preserved and with complete selectivity for the Z‐stereoisomer. Additionally, an aldehyde group was introduced by C–H amidation, enabling oxime ligation for the installation of an even greater range of functionality. The thiostrepton derivatives generally maintain antimicrobial activity, and importantly, eight of the derivatives displayed improved aqueous solubility (up to 28‐fold), thereby addressing a key shortcoming of this antibiotic. The exceptional functional group compatibility and site selectivity of Co(III)‐catalyzed C(sp2)–H Dha amidation suggests that this approach could be generalized to other natural products and biopolymers containing Dha residues. [...]
    Tue, Nov 19, 2019
    Source: Angewandte Chemie Int. edition Category: CHEMISTRY GENERAL
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