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1.
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
2.
Emily J. Hopkins Dr. Yurii Prots Dr. Ulrich Burkhardt Dr. Yves Watier Dr. Zhiwei Hu Dr. Chang‐Yang Kuo Dr. Jen‐Che Chiang Dr. Tun‐Wen Pi Dr. Arata Tanaka Prof. Liu Hao Tjeng Dr. Martin Valldor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7938-7943
Through a solid‐state reaction, a practically phase pure powder of Ba3V2S4O3 was obtained. The crystal structure was confirmed by X‐ray single‐crystal and synchrotron X‐ray powder diffraction (P63, a=10.1620(2), c=5.93212(1) Å). X‐ray absorption spectroscopy, in conjunction with multiplet calculations, clearly describes the vanadium in charge‐disproportionated VIIIS6 and VVSO3 coordinations. The compound is shown to be a strongly correlated Mott insulator, which contradicts previous predictions. Magnetic and specific heat measurements suggest dominant antiferromagnetic spin interactions concomitant with a weak residual ferromagnetic component, and that intrinsic geometric frustration prevents long‐range order from evolving. 相似文献
3.
Synthesis of poly(ω‐pentadecalactone)‐b‐poly(acrylate) diblock copolymers via a combination of enzymatic ring‐opening and RAFT polymerization techniques 下载免费PDF全文
Robin L. Pflughaupt Sally A. Hopkins Peter M. Wright Andrew P. Dove 《Journal of polymer science. Part A, Polymer chemistry》2016,54(20):3326-3335
Herein the first reported preparation of diblock copolymers of the polyethylene‐like polyester poly(ω‐pentadecalactone) (PPDL) via a combination of enzymatic ring‐opening polymerization (eROP) and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization techniques is described. PPDL was synthesized via eROP using Novozyme 435 as a catalyst and a bifunctional initiator/chain transfer agent (CTA) appropriate for the eROP of ω‐pentadecalactone (PDL) and RAFT polymerization of acrylic and styrenic monomers. Chain growth of the PPDL macro‐CTA was performed to prepare acrylic and styrenic diblock copolymers of PPDL, and demonstrates a facile, metal‐free, and “greener” alternative to preparing acrylic diblock copolymers of polyethylene (PE). Diblock copolymer architecture was substantiated via analysis of 1H NMR spectroscopic, UV‐GPC chromatographic, DSC onset crystallization (Tc), and MALDI‐ToF mass spectrometric data. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3326–3335 相似文献
4.
Mathematische Semesterberichte - We describe in the form of a dialogue a development of various reflections on the combinatorics of set partitions; among the topics we pursue are... 相似文献
5.
Megan Douglass Sean Hopkins Rashmi Pandey Priya Singha Megan Norman Hitesh Handa 《Macromolecular bioscience》2021,21(1)
The novel use of nanofibers as a physical barrier between blood and medical devices has allowed for modifiable, innovative surface coatings on devices ordinarily plagued by thrombosis, delayed healing, and chronic infection. In this study, the nitric oxide (NO) donor S‐nitrosoglutathione (GSNO) is blended with the biodegradable polymers polyhydroxybutyrate (PHB) and polylactic acid (PLA) for the fabrication of hemocompatible, antibacterial nanofibers tailored for blood‐contacting applications. Stress/strain behavior of different concentrations of PHB and PLA is recorded to optimize the mechanical properties of the nanofibers. Nanofibers incorporated with different concentrations of GSNO (10, 15, 20 wt%) are evaluated based on their NO‐releasing kinetics. PLA/PHB + 20 wt% GSNO nanofibers display the greatest NO release over 72 h (0.4–1.5 × 10?10 mol mg?1 min?1). NO‐releasing fibers successfully reduce viable adhered bacterial counts by ≈80% after 24 h of exposure to Staphylococcus aureus. NO‐releasing nanofibers exposed to porcine plasma reduce platelet adhesion by 64.6% compared to control nanofibers. The nanofibers are found noncytotoxic (>95% viability) toward NIH/3T3 mouse fibroblasts, and 4′,6‐diamidino‐2‐phenylindole and phalloidin staining shows that fibroblasts cultured on NO‐releasing fibers have improved cellular adhesion and functionality. Therefore, these novel NO‐releasing nanofibers provide a safe antimicrobial and hemocompatible coating for blood‐contacting medical devices. 相似文献
6.
The thermochemical properties of superbase species derived from cyclopropeneimine are estimated by computations on systems of isodesmic reactions. Proton affinities, gas phase basicities, and pKa values are well represented by computations incorporating G4 and CBS‐QB3 schemes augmented for large systems by DFT calculations with functionals M06‐2X and ωB97DX in the cc‐pVTZ Dunning basis. Our calculations show that relative base strengths in gas are enhanced by alkyl substitution, either by methyl groups or larger species. For acetonitrile solution, alkyl substitution seems to weaken the base. © 2013 Wiley Periodicals, Inc. 相似文献
7.
Florian Pachel Dr. Markus Ströbele Carl P. Romao David Enseling Thomas Jüstel Prof. Dr. Hans-Jürgen Meyer 《欧洲无机化学杂志》2023,26(19):e202300096
The new heteroleptic tungsten iodide cluster compound [W6I12(NCC6H5)2] is presented. The synthesis is carried-out from Cs2W6I14 and ZnI2 under solvothermal conditions in benzonitrile solution, yielding red cube-shaped crystals. [W6I12(NCC6H5)2] represents a heteroleptic [W6I8]-type cluster bearing four apical iodides and two benzonitrile ligands. Molecular [W6I12(NCC6H5)2] clusters form a robust hydrogen bridged crystal structure with high thermal stability and high resistibility against hydrolysis. The electronic structure is analyzed by quantum chemical methods of the calculated electron localization function (ELF) and the band structure. Photoluminescence measurements are performed to verify and describe the photophysical properties of [W6I12(NCC6H5)2]. Finally, the photocatalytic properties of [W6I12(NCC6H5)2] are evaluated as a proof-of-concept. 相似文献
8.
Dr. Vitthal N. Yadav Prof. Angiolina Comotti Prof. Piero Sozzani Dr. Silvia Bracco Prof. Tore Bonge‐Hansen Dr. Martin Hennum Prof. Carl Henrik Görbitz 《Angewandte Chemie (International ed. in English)》2015,54(52):15684-15688
Dipeptides with two hydrophobic side chains have proved to be an exceptional source of microporous organic materials, but since previous structures were limited to the incorporation of only proteinogenic residues, their full potential as adsorbents has remained unexplored. Single‐crystal XRD data for ten new compounds with non‐proteinogenic L ‐2‐aminobutanoic acid and/or L ‐2‐amino‐pentanoic acid are presented. The gas‐phase accessibility of their crystal pores, with cross‐sections of 2.3 to 5.1 Å, was monitored by CO2 and CH4 adsorption isotherms. Included CO2 was also detected spectroscopically by 2D MAS NMR. An extensive conformational analysis reveals that the use of linear rather than branched side chains (such as L ‐valine and L ‐isoleucine) affords peptides with a greater degree of conformational freedom and yields more‐flexible channel surfaces that may easily adapt to a series of potential guest molecules. 相似文献
9.
Leon N. Schneider Dr. Eva-Maria Tanzer Krauel Dr. Carl Deutsch Dr. Klaus Urbahns Tobias Bischof Kristina A. M. Maibom Dr. Johannes Landmann Dr. Fabian Keppner Dr. Christoph Kerpen Dr. Michael Hailmann Ludwig Zapf Tanja Knuplez Dr. Rüdiger Bertermann Dr. Nikolai V. Ignat'ev Prof. Dr. Maik Finze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10973-10978
Fluorinated groups are essential for drug design, agrochemicals, and materials science. The bis(trifluoromethyl)amino group is an example of a stable group that has a high potential. While the number of molecules containing perfluoroalkyl, perfluoroalkoxy, and other fluorinated groups is steadily increasing, examples with the N(CF3)2 group are rare. One reason is that transfer reagents are scarce and metal-based storable reagents are unknown. Herein, a set of CuI and AgI bis(trifluoromethyl)amido complexes stabilized by N- and P-donor ligands with unprecedented stability are presented. The complexes are stable solids that can even be manipulated in air for a short time. They are bis(trifluoromethyl)amination reagents as shown by nucleophilic substitution and Sandmeyer reactions. In addition to a series of benzylbis(trifluoromethyl)amines, 2-bis(trifluoromethyl)amino acetate was obtained, which, upon hydrolysis, gives the fluorinated amino acid N,N-bis(trifluoromethyl)glycine. 相似文献
10.
Apsara K. Herath Manoj R. Bhandari Delphine Gout Muhammed Yousufuddin Carl J. Lovely 《Tetrahedron letters》2017,58(41):3913-3918
The utility of the thio acid-azide coupling reaction to afford amides is explored in imidazole-containing substrates for application in the total synthesis of examples of oroidin alkaloids. Good yields of the expected amides are obtained in both monomeric and dimeric substrates. Bis azides react preferentially at the 2-azido position but hydrosulfenylation and reduction interfere. 2-Thiophenyl and 2-oxo groups were evaluated as 2-amino surrogates, the thioether delivered the expected amide, whereas 2-imidazolone gave a mixture of the expected amide and the hydrosulfenylation product. 相似文献