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31.
- and -dialkylvinyloxyboranes, prepared directly from cyclohexyl ethyl ketone, undergo stereo-selective aldol condensations to provide - -β-hydroxy-α-methylketones, respectively. 相似文献
32.
Horný L Petraco ND Pak C Schaefer HF 《Journal of the American Chemical Society》2002,124(20):5861-5864
The optimized geometries, adiabatic electron affinities, and IR-active vibrational frequencies have been predicted for the long linear carbon chains HC(2n)H. The B3LYP density functional combined with the DZP basis set was used in this theoretical study. The computed physical properties are discussed. The predicted electron affinities form a remarkably regular sequence: 1.78 (HC(12)H), 2.08 (HC(14)H), 2.32 (HC(16)H), 2.53 (HC(18)H), 2.69 (HC(20)H), 2.83 (HC(22)H), and 2.95 eV (HC(24)H). The predicted structures display an alternating triple and very short single bond pattern, with the degree of bond alternation significantly less for the radical anions. 相似文献
33.
Horn JM Song Z Potapenko DV Hrbek J White MG 《The journal of physical chemistry. B》2005,109(1):44-47
Temperature programmed desorption (TPD), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM) have been used to characterize molybdenum carbide nanoparticles prepared on a Au(111) substrate. The MoC(x) nanoparticles were formed by Mo metal deposition onto a reactive multilayer of ethylene, which was physisorbed on a Au(111) substrate at low temperatures (<100 K). The resulting clusters have an average diameter of approximately 1.5 nm and aggregate in the fcc troughs located on either side of the elbows of the reconstructed Au(111) surface. Core level XPS shows that the electronic environment of the Mo and C atoms in the nanoparticles is similar to that found in Mo(2)C(0001) single crystals and carburized Mo metal surfaces. Peak intensities in XPS and AES spectra were used to estimate an average Mo/C atomic ratio of 1.2 +/- 0.3 for nanoparticles annealed above 600 K. 相似文献
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Yoshiki Shibuya Ryoichi Tatara Yivan Jiang Yang Shao‐Horn Jeremiah A. Johnson 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):448-455
The properties of polymeric materials are dictated not only by their composition but also by their molecular architecture. Here, by employing brush‐first ring‐opening metathesis polymerization (ROMP), norbornene‐terminated poly(ethylene oxide) (PEO) macromonomers ( MM‐n , linear architecture), bottlebrush polymers ( Brush‐n , comb architecture), and brush‐arm star polymers ( BASP‐n , star architecture), where n indicates the average degree of polymerization (DP) of PEO, are synthesized. The impact of architecture on the thermal properties and Li+ conductivities for this series of PEO architectures is investigated. Notably, in polymers bearing PEO with the highest degree of polymerization, irrespective of differences in architecture and molecular weight (~100‐fold differences), electrolytes with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an Li+ source exhibit normalized ionic conductivities (σn) within only 4.9 times difference (σn = 29.8 × 10?5 S cm?1 for MM‐45 and σn = 6.07 × 10?5 S cm?1 for BASP‐45 ) at a concentration of Li+ r = [Li+]/[EO] = 1/12 at 50 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 448–455 相似文献
36.
Michael Esseling Annamaria Zaltron Wolfgang Horn Cornelia Denz 《Laser \u0026amp; Photonics Reviews》2015,9(1):98-104
This contribution presents an optofluidic droplet router which is able to route and steer microdroplets using optically induced forces created solely by the bulk photovoltaic effect on a nonlinear substrate. The combination of microfluidic tools with the properties of a photorefractive crystal allows for the generation of dielectrophoretic forces that can be either repulsive, leading to virtual barriers, or attractive, creating virtual rails. The sign of these forces is solely determined by the electrical properties of the liquid medium under investigation. Moreover, the induced structures on the bottom of the microfluidic channel are optically reconfigurable, so that the same device can easily be adopted for different purposes. Appropriate droplet‐generating devices are fabricated by UV illumination of SU‐8 and polydimethylsiloxane replica molding of the master structures. The bottom of the channels is formed by an iron‐doped lithium niobate crystal, whose internal electric fields are induced by structured illumination patterns and exert dielectrophoretic forces on droplets in the microfluidic section.
37.
The Activation of Sulfur Hexafluoride at Highly Reduced Low‐Coordinate Nickel Dinitrogen Complexes 下载免费PDF全文
Dipl.‐Chem. Patrick Holze Dipl.‐Chem. Bettina Horn Prof. Dr. Christian Limberg Dipl.‐Chem. Corinna Matlachowski Dr. Stefan Mebs 《Angewandte Chemie (International ed. in English)》2014,53(10):2750-2753
The greenhouse gas sulfur hexafluoride is the common standard example in the literature of a very inert inorganic small molecule that is even stable against O2 in an electric discharge. However, a reduced β‐diketiminate nickel species proved to be capable of converting SF6 into sulfide and fluoride compounds at ambient standard conditions. The fluoride product complex features an unprecedented [NiF]+ unit, where the Ni atom is only three‐coordinate, while the sulfide product exhibits a rare almost linear [Ni(μ‐S)Ni]2+ moiety. The reaction was monitored applying 1H NMR, IR and EPR spectroscopic techniques resulting in the identification of an intermediate nickel complex that gave insight into the mechanism of the eight‐electron reduction of SF6. 相似文献
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Victoria A. Piunova Hans W. Horn Gavin O. Jones Julia E. Rice Robert D. Miller 《Journal of polymer science. Part A, Polymer chemistry》2016,54(4):563-569
This study reports an application of trichloroethanol (TCE) as a bifunctional initiator for the synthesis of block copolymers (BCPs) by organocatalyzed ring‐opening polymerization (OROP) and atom transfer radical polymerization (ATRP). TCE was employed to synthesize a low dispersity poly (valerolactone) macroinitiator, which was subsequently used for the ATRP of tert‐butyl methacrylate. While it is known that TCE can serve as an initiator in ATRP, the ability to induce polymerization under OROP is reported for the first time. The formation of well‐defined BCPs was confirmed by gel permeation chromatography and 1H NMR. Computational studies were performed to obtain a molecular‐level understanding of the ring‐opening polymerization mechanism involving TCE as initiator. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 563–569 相似文献