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11.
Pit van Bonn Prof. Dr. Carsten Bolm Dr. José G. Hernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2576-2580
Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide. 相似文献
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Lehmann P Symietz C Brezesinski G Krass H Kurth DG 《Langmuir : the ACS journal of surfaces and colloids》2005,21(13):5901-5906
A detailed analysis of a metallosupramolecular polyelectrolyte-amphiphile complex (PAC) at the air-water interface is presented. Langmuir isotherms, Brewster angle microscopy, and X-ray reflectance and diffraction methods are employed to investigate the structure of the Langmuir monolayers. The PAC is self-assembled from 1,3-bis[4'-oxa-(2,2':6',2' '-terpyridinyl)]propane, iron acetate, and dihexadecyl phosphate (DHP). Spreading the PAC at the air-water interface results in a monolayer that consists of two strata. DHP forms a monolayer at the top of the interface, while the metallosupramolecular polyelectrolyte is immersed in the aqueous subphase. Both strata are coupled to each other through electrostatic interactions. The monolayers can be transferred onto solid substrates, resulting in well-ordered multilayers. Such multilayers are model systems for well-ordered metal ions in two dimensions. 相似文献
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Zukalová Markéta Pitňa Lásková Barbora Mocek Karel Zukal Arnošt Bouša Milan Kavan Ladislav 《Journal of Solid State Electrochemistry》2018,22(8):2545-2552
Journal of Solid State Electrochemistry - Nanocrystalline Na2Ti3O7 material is prepared by a newly developed sol-gel procedure. The sol-gel made Na2Ti3O7 calcined at 500 °C possesses... 相似文献
14.
Abraham Warshawsky Monica M.B. Fieberg Pit Mihalik Tarry G. Murphy Yvonne B 《Separation & Purification Reviews》2013,42(2):209-265
Styrene-divinylbenzene copolymers incorporating isothiourea functional groups show a remarkable affinity for platinum-group-metal (PGM) ions in chloride media, The mode of ion binding to the resin depends on the equilibria between isothiourea (free base) form and isothiouronium (conjugated acid) form, This in return is related to matrix structure, A. resin, Monivex, which shows high binding capacities for PGM ions in high acidities (2–6M HC1) is described. Equilibrium, rate and selectivity data, as well as process application data is presented and discussed, Electron microprobe studies are used to follow chemical changes in resin beads and ion regeneration patterns. 相似文献
15.
M. Sc. Akash Kaithal Pit van Bonn Dr. Markus Hölscher Prof. Dr. Walter Leitner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):221-226
Highly selective β-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)2Br[HN(C2H4PiPr2)2]] 1 ([HN(C2H4PiPr2)2]=MACHO-iPr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β-position, opening a pathway to “biohybrid” molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal–ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C−C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules 相似文献
16.
Patrick M. Becker Dr. Christoph Förster Dr. Luca M. Carrella Pit Boden David Hunger Prof. Joris van Slageren Prof. Markus Gerhards Prof. Eva Rentschler Prof. Katja Heinze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(32):7199-7204
The chromium(III) complex [CrIII(ddpd)2]3+ (molecular ruby; ddpd=N,N′-dimethyl-N,N′-dipyridine-2-yl-pyridine-2,6-diamine) is reduced to the genuine chromium(II) complex [CrII(ddpd)2]2+ with d4 electron configuration. This reduced molecular ruby represents one of the very few chromium(II) complexes showing spin crossover (SCO). The reversible SCO is gradual with T1/2 around room temperature. The low-spin and high-spin chromium(II) isomers exhibit distinct spectroscopic and structural properties (UV/Vis/NIR, IR, EPR spectroscopies, single-crystal XRD). Excitation of [CrII(ddpd)2]2+ with UV light at 20 and 290 K generates electronically excited states with microsecond lifetimes. This initial study on the unique reduced molecular ruby paves the way for thermally and photochemically switchable magnetic systems based on chromium complexes complementing the well-established iron(II) SCO systems. 相似文献
17.
A computer-aided method to assist the chromatographer in the determination of initial conditions in reversed-phase HPLC has been developed. ChromDream software predicts the optimum methanol, acetonitrile or tetrahydrofuran concentration in a mobile phase on the basis of the structural formulae of the compounds. The effects of the concentration of an organic solvent in water on retention and chromatograms of compound mixtures are simulated. Reversed-phase column parameters responsible for selectivity and retention are calculated. Volume and energy increments for more than 100 volume fragments and more than 30 bond dipoles have been derived. An approach for the selection of reference compounds for column calibration is proposed. 相似文献
18.
Dr. Alvaro Mayoral Dr. Qing Zhang Yi Zhou Pengyu Chen Dr. Yanhang Ma Dr. Taro Monji Dr. Pit Losch Dr. Wolfgang Schmidt Prof. Ferdi Schüth Dr. Hajime Hirao Prof. Jihong Yu Prof. Osamu Terasaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19678-19685
Zeolites are becoming more versatile in their chemical functions through rational design of their frameworks. Therefore, direct imaging of all atoms at the atomic scale, basic units (Si, Al, and O), heteroatoms in the framework, and extra-framework cations, is needed. TEM provides local information at the atomic level, but the serious problem of electron-beam damage needs to be overcome. Herein, all framework atoms, including oxygen and most of the extra-framework Na cations, are successfully observed in one of the most electron-beam-sensitive and lowest framework density zeolites, Na- LTA . Zeolite performance, for instance in catalysis, is highly dependent on the location of incorporated heteroatoms. Fe single atomic sites in the MFI framework have been imaged for the first time. The approach presented here, combining image analysis, electron diffraction, and DFT calculations, can provide essential structural keys for tuning catalytically active sites at the atomic level. 相似文献
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Pit Boden Patrick Di Martino-Fumo Jasmin M. Busch Florian R. Rehak Sophie Steiger Dr. Olaf Fuhr Dr. Martin Nieger Daniel Volz Prof. Willem Klopper Prof. Stefan Bräse Prof. Markus Gerhards 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5439-5452
To develop new and flexible CuI containing luminescent substances, we extend our previous investigations on two metal-centered species to four metal-centered complexes. These complexes could be a basis for designing new organic light-emitting diode (OLED) relevant species. Both the synthesis and in-depth spectroscopic analysis, combined with high-level theoretical calculations are presented on a series of tetranuclear CuI complexes with a halide containing Cu4X4 core (X=iodide, bromide or chloride) and two 2-(diphenylphosphino)pyridine bridging ligands with a methyl group in para (4-Me) or ortho (6-Me) position of the pyridine ring. The structure of the electronic ground state is characterized by X-ray diffraction, NMR, and IR spectroscopy with the support of theoretical calculations. In contrast to the para system, the complexes with ortho-substituted bridging ligands show a remarkable and reversible temperature-dependent dual phosphorescence. Here, we combine for the first time the luminescence thermochromism with time-resolved FTIR spectroscopy. Thus, we receive experimental data on the structures of the two triplet states involved in the luminescence thermochromism. The transient IR spectra of the underlying triplet metal/halide-to-ligand charge transfer (3M /XLCT) and cluster-centered (3CC) states were obtained and interpreted by comparison with calculated vibrational spectra. The systematic and significant dependence of the bridging halides was analyzed. 相似文献