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71.
Dr. Ju Bao Dr. Bindumadhav Marathe Dr. Elena A. Govorkova Prof. Jie J. Zheng 《Angewandte Chemie (International ed. in English)》2016,55(10):3438-3441
The neuraminidase (NA) inhibitor, oseltamivir, is a widely used anti‐influenza drug. However, oseltamivir‐resistant H1N1 influenza viruses carrying the H275Y NA mutation spontaneously emerged as a result of natural genetic drift and drug treatment. Because H275Y and other potential mutations may generate a future pandemic influenza strain that is oseltamivir‐resistant, alternative therapy options are needed. Herein, we show that a structure‐based computational method can be used to identify existing drugs that inhibit resistant viruses, thereby providing a first line of pharmaceutical defense against this possible scenario. We identified two drugs, nalidixic acid and dorzolamide, that potently inhibit the NA activity of oseltamivir‐resistant H1N1 viruses with the H275Y NA mutation at very low concentrations, but have no effect on wild‐type H1N1 NA even at a much higher concentration, suggesting that the oseltamivir‐resistance mutation itself caused susceptibility to these drugs. 相似文献
72.
Dr. Vijay Singh Dr. Mudit Dixit Dr. Monica Kosa Prof. Dan Thomas Major Prof. Elena Levi Prof. Dr. Doron Aurbach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5269-5276
The most intriguing feature of metal–metal bonds in inorganic compounds is an apparent lack of correlation between the bond order and the bond length. In this study, we combine a variety of literature data obtained by quantum chemistry and our results based on the empirical bond valence model (BVM), to confirm for the first time the existence of a normal exponential correlation between the effective bond order (EBO) and the length of the metal–metal bonds. The difference between the EBO and the formal bond order is attributed to steric conflict between the (TM)n cluster (TM=transition metal) and its environment. This conflict, affected mainly by structural type, should cause high lattice strains, but electron redistribution around TM atoms, evident from the BVM calculations, results in a full or partial strain relaxation. 相似文献
73.
Romain Bénéteau Anne Boussonnière Jean‐Christophe Rouaud Prof. Dr. Jacques Lebreton Dr. Jérôme Graton Prof. Dr. Denis Jacquemin Dr. Muriel Sebban Prof. Dr. Hassan Oulyadi Ghanem Hamdoun Dr. Amber N. Hancock Prof. Dr. Carl H. Schiesser Dr. Fabrice Dénès 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4809-4824
α‐Bromo aluminium acetals are suitable substrates for Ueno–Stork‐like radical cyclisations affording γ‐lactols and acid‐sensitive methylene‐γ‐lactols in high yields. The mechanistic study herein sets the scope and limitation of this reaction. The influence of the halide (or chalcogenide) atom X (X=Cl, Br, I, SPh, SePh) in the precursors α‐haloesters, as well as influence of the solvent and temperature was studied. The structure of the aluminium acetal intermediates resulting from the reduction of the corresponding α‐haloesters has been investigated by low‐temperature 13C‐INEPT diffusion‐ordered NMR spectroscopy (DOSY) experiments and quantum calculations, providing new insights into the structures of these thermally labile intermediates. Oxygen‐bridged dimeric structures with a planar Al2O2 ring are proposed for the least hindered aluminium acetals, while monomeric structures seem to prevail for the most hindered species. A comparison against the radical cyclisation of aluminium acetals derived from allyl and propargyl alcohols with the parent Ueno–Stork has been made at the BHandHLYP/6‐311++G(d,p) level of theory, highlighting mechanistic similarities and differences. 相似文献
74.
Jiaojiao Huang Chong‐Zhi Wang Xiaoli Gu Yankun Gao Hongjuan Zhang Shuhu Du Lina Chen Chun‐Su Yuan 《Biomedical chromatography : BMC》2016,30(2):117-125
A novel molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization with baicalein (BAI) as the template and used as solid‐phase extraction (SPE) adsorbent, aiming at the affinity isolation and selective knockout of BAI from Scutellaria baicalensis Georgi (SB). We used computational simulation to predict the optimal functional monomer, polymerization solvent and molar ratio of template to functional monomer. Characterization and performance tests revealed that MIP exhibited uniform spherical morphology, rapid binding kinetics, and higher adsorption capacity for BAI compared with nonimprinted polymer (NIP). The application of MIP in SPE coupled with high‐performance liquid chromatography to extract BAI from SB showed excellent recovery (94.3%) and purity (97.0%). Not only the single BAI compound, but also the BAI‐removed SB extract was obtained by one‐step process. This new method is useful for isolation and knockout of key bioactive compounds from herbal medicines. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
75.
Marco Carboni Dr. Andrea Giacomo Marrani Dr. Riccardo Spezia Dr. Sergio Brutti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17188-17203
The reaction thermodynamics of the 1,2‐dimethoxyethane (DME), a model solvent molecule commonly used in electrolytes for Li?O2 rechargeable batteries, has been studied by first‐principles methods to predict its degradation processes in highly oxidizing environments. In particular, the reactivity of DME towards the superoxide anion O2? in oxygen‐poor or oxygen‐rich environments is studied by density functional calculations. Solvation effects are considered by employing a self‐consistent reaction field in a continuum solvation model. The degradation of DME occurs through competitive thermodynamically driven reaction paths that end with the formation of partially oxidized final products such as formaldehyde and methoxyethene in oxygen‐poor environments and methyl oxalate, methyl formate, 1‐formate methyl acetate, methoxy ethanoic methanoic anhydride, and ethylene glycol diformate in oxygen‐rich environments. This chemical reactivity indirectly behaves as an electroactive parasitic process and therefore wastes part of the charge exchanged in Li?O2 cells upon discharge. This study is the first complete rationale to be reported about the degradation chemistry of DME due to direct interaction with O2?/O2 molecules. These findings pave the way for a rational development of new solvent molecules for Li?O2 electrolytes. 相似文献
76.
77.
Dr. Roland Frach Patrick Kibies Saraphina Böttcher Tim Pongratz Steven Strohfeldt Simon Kurrmann Dr. Joerg Koehler Martin Hofmann Prof. Dr. Werner Kremer Prof. Dr. Hans Robert Kalbitzer Prof. Dr. Oliver Reiser Prof. Dr. Dominik Horinek Prof. Dr. Stefan M. Kast 《Angewandte Chemie (International ed. in English)》2016,55(39):11713-11713
78.
Dr. Joel E. Schmidt Donglong Fu Dr. Michael W. Deem Prof. Dr. Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2016,55(52):16044-16048
Zeolites, having widespread applications in chemical industries, are often synthesized using organic templates. These can be cost‐prohibitive, motivating investigations into their role in promoting crystallization. Herein, the relationship between framework structure, chemical composition, synthesis conditions and the conformation of the occluded, economical template tetraethylammonium (TEA+) has been systematically examined by experimental and computational means. The results show two distinct regimes of occluded conformer tendencies: 1) In frameworks with a large stabilization energy difference, only a single conformer was found (BEA, LTA and MFI). 2) In the frameworks with small stabilization energy differences (AEI, AFI, CHA and MOR), less than the interconversion of TEA+ in solution, a heteroatom‐dependent (Al, B, Co, Mn, Ti, Zn) distribution of conformers was observed. These findings demonstrate that host–guest chemistry principles, including electrostatic interactions and coordination chemistry, are as important as ideal pore‐filling. 相似文献
79.
Stacking and Electrostatic Interactions Drive the Stereoselectivity of Silylium‐Ion Asymmetric Counteranion‐Directed Catalysis 下载免费PDF全文
Trevor J. Seguin Prof. Steven E. Wheeler 《Angewandte Chemie (International ed. in English)》2016,55(51):15889-15893
Computational analysis shows that the enantioselectivity of asymmetric Lewis‐acid organocatalysis of the Diels–Alder cycloaddition of cyclopentadiene to cinnamates arises from stacking interactions that favor the addition of the diene to the more hindered face of the dienophile, while electrostatic interactions control the diastereoselectivity by selectively stabilizing the endo transition state. These results not only explain the stereoselectivity of these silylium‐ion‐ACDC reactions but should also guide the development of more effective ion‐pairing asymmetric organocatalysts. 相似文献
80.
Riccardo Baron Daniel Trzesniak Alex H de Vries Andreas Elsener Siewert J Marrink Wilfred F van Gunsteren 《Chemphyschem》2007,8(3):452-461
Thermodynamic data are often used to calibrate or test amomic-level (AL) force fields for molecular dynamics (MD) simulations. In contrast, the majority of coarse-grained (CG) force fields do not rely extensively on thermodynamic quantities. Recently, a CG force field for lipids, hydrocarbons, ions, and water, in which approximately four non-hydrogen atoms are mapped onto one interaction site, has been proposed and applied to study various aspects of lipid systems. To date, no extensive investigation of its capability to describe salvation thermodynamics has been undertaken. In the present study, a detailed picture of vaporization, solvation, and phase-partitioning thermodynamics for liquid hydrocarbons and water was obtained at CG and AL resolutions, in order to compare the two types or models and evaluate their ability to describe thermodynamic properties in the temperature range between 263 and 343 K. Both CG and AL models capture the experimental dependence of the thermodynamic properties on the temperature, albeit a systematically weaker dependence is found for the CG model. Moreover, deviations are found for solvation thermodynamics and for the corresponding enthalpy-entropy compensation for the CG model. Particularly water/oil repulsion seems to be overestimated. However, the results suggest that the thermodynamic properties considered should be reproducible by a CG model provided it is reparametrized on the basis of these liquid-phase properties. 相似文献