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71.
72.
Elisabeth Siebert Marius Horch Yvonne Rippers Johannes Fritsch Stefan Frielingsdorf Oliver Lenz Francisco VelazquezEscobar Friedrich Siebert Lars Paasche Uwe Kuhlmann Friedhelm Lendzian Maria‐Andrea Mroginski Ingo Zebger Peter Hildebrandt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(19):5267-5270
73.
Frederik Weber Georg Koller Robert Schennach Ingo Bernt Rene Eckhart 《Cellulose (London, England)》2013,20(6):2719-2729
In this paper the influence of charged species on the sheet strength of viscose fibres was investigated. Four samples of chemical modified viscose fibres, as well as a reference fibre were studied. The swelling of these viscose fibres and the breaking length of hand sheets have been determined. Comparing the results, the influence of both, swelling and surface charge on the bonding force, is evident. The allocation of the charges, induced by cationic starch and Carboxmethylcellulose, has been analyzed by Titration, attenuated total reflection spectroscopy (ATR) and X-ray photoelectron spectroscopy (XPS). Titration was used to make a first estimation of the charge distribution within the fibre. Using ATR and XPS, more detailed information about the surface charge has been achieved. All measurement methods showed a significant amount of charge on the fibre surface. 相似文献
74.
Ingo Münch 《PAMM》2015,15(1):599-600
Solid-state phase-transformation often deals with coupled field variables like mechanical stress or electric potential on different scales compared to the size of phase transition. Further, highly nonlinear equations rule the phase parameter. Thus, required mesh density to approximate phase field variables is often higher than for coupled fields. Finite element techniques applying h- or p-adaptivity can help to increase the efficiency of such simulations. Therefore, it is important to define a benchmark test to verify numerical approaches. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
75.
Antoine Barthélemy Dr. Harald Scherer Prof. Dr. Ingo Krossing 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(53):e202201369
The tetracationic, univalent cluster compounds [{M(dmpe)}4]4+ (M=Ga, In; dmpe=bis(dimethylphosphino)ethane) were synthesized as their pf salts ([pf]−=[Al(ORF)4]−; RF=C(CF3)3). The four-membered ring in [{M(dmpe)}4]4+ is slightly puckered for M=Ga and almost square planar for M=In. Yet, although structurally similar, only the gallium cluster is prevalent in solution, while the indium cluster forms temperature dependent equilibria that include even the monomeric cation [In(dmpe)]+. This system is the first report of one and the same ligand inducing formation of isoelectronic and isostructural gallium/indium cluster cations. The system allows to study systematically analogies and differences with thermodynamic considerations and bonding analyses, but also to outline perspectives for bond activation using cationic, subvalent group 13 clusters. 相似文献
76.
Kim Glootz Antoine Barthlemy Ingo Krossing 《Angewandte Chemie (International ed. in English)》2021,60(1):208-211
The earth‐metal olefin complex [Ga I (COD)2]+[Al(ORF)4]? (COD=1,5‐cyclooctadiene; RF=C(CF3)3) constitutes the first homoleptic olefin complex of any main‐group metal accessible as a bulk compound. It is straight forward to prepare in good yield and constitutes an olefin complex of a main‐group metal that—similar to many transition‐metals—may adopt the +1 and +3 oxidation states opening potential applications. Crystallographic‐, vibrational‐ and computational investigations give an insight to the atypical bonding between an olefin and a main‐group metal. They are compared to classical transition‐metal relatives. 相似文献
77.
Influence of higher harmonics of the undulator in X‐ray polarimetry and crystal monochromator design 下载免费PDF全文
Berit Marx‐Glowna Kai S. Schulze Ingo Uschmann Tino Kämpfer Günter Weber Christoph Hahn Hans‐Christian Wille Kai Schlage Ralf Röhlsberger Eckhart Förster Thomas Stöhlker Gerhard G. Paulus 《Journal of synchrotron radiation》2015,22(5):1151-1154
The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel‐cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs. 相似文献
78.
Catalytic,Asymmetric Synthesis of Phosphonic γ‐(Hydroxyalkyl)butenolides with Contiguous Quaternary and Tertiary Stereogenic Centers 下载免费PDF全文
Marcus Frings Dr. Isabelle Thomé Dr. Ingo Schiffers Dr. Fangfang Pan Prof. Dr. Carsten Bolm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1691-1700
A procedure that enables high yielding access to phosphonic γ‐(hydroxyalkyl)butenolides with excellent regio‐, diastereo‐ and enantiocontrol is reported. The simultaneous construction of up to two adjacent quaternary stereogenic centers by a catalytic asymmetric vinylogous Mukaiyama aldol reaction unites biologically and medicinally relevant entities, namely α‐hydroxy phosphonates and γ‐(hydroxyalkyl)butenolides. This is achieved by utilizing a readily available chiral copper‐sulfoximine catalyst showing a broad functional group tolerance for both the electrophilic and nucleophilic reactants. A discussion about potential factors affecting the observed level of enantioselectivity, which stems from the enantiopure sulfoximine ligand, is also included. 相似文献
79.
Dipl.‐Chem. Alexander Rupp Dr. Nataliya Roznyatovskaya Dr. Harald Scherer Dr. Witali Beichel Petra Klose Carola Sturm Dr. Anke Hoffmann Dr. Jens Tübke Prof. Dr. Thorsten Koslowski Prof. Dr. Ingo Krossing 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9794-9804
Several, partly new, ionic liquids (ILs) containing imidazolium and ammonium cations as well as the medium‐sized [NTf2]? (0.230 nm3; Tf=CF3SO3?) and the large [Al(hfip)4]? (0.581 nm3; hfip=OC(H)(CF3)2) anions were synthesized and characterized. Their temperature‐dependent viscosities and conductivities between 25 and 80 °C showed typical Vogel–Fulcher–Tammann (VFT) behavior. Ion‐specific self‐diffusion constants were measured at room temperature by pulsed‐gradient stimulated‐echo (PGSTE) NMR experiments. In general, self‐diffusion constants of both cations and anions in [Al(hfip)4]?‐based ILs were higher than in [NTf2]?‐based ILs. Ionicities were calculated from self‐diffusion constants and measured bulk conductivities, and showed that [Al(hfip)4]?‐based ILs yield higher ionicities than their [NTf2]? analogues, the former of which reach values of virtually 100 % in some cases.From these observations it was concluded that [Al(hfip)4]?‐based ILs come close to systems without any interactions, and this hypothesis is underlined with a Hirshfeld analysis. Additionally, a robust, modified Marcus theory quantitatively accounted for the differences between the two anions and yielded a minimum of the activation energy for ion movement at an anion diameter of slightly greater than 1 nm, which fits almost perfectly the size of [Al(hfip)4]?. Shallow Coulomb potential wells are responsible for the high mobility of ILs with such anions. 相似文献
80.
Photoionization and Pyrolysis of a 1,4‐Azaborinine: Retro‐Hydroboration in the Cation and Identification of Novel Organoboron Ring Systems 下载免费PDF全文
Fabian Holzmeier Dipl.‐Chem. Melanie Lang Dr. Patrick Hemberger Dr. Andras Bodi Dipl.‐Chem. Marius Schäfer Dr. Rian D. Dewhurst Prof. Dr. Holger Braunschweig Prof. Dr. Ingo Fischer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9683-9692
The photoionization and dissociative photoionization of 1,4‐di‐tert‐butyl‐1,4‐azaborinine by means of synchrotron radiation and threshold photoelectron photoion coincidence spectroscopy is reported. The ionization energy of the compound was determined to be 7.89 eV. Several low‐lying electronically excited states in the cation were identified. The various pathways for dissociative photoionization were modeled by statistical theory, and appearance energies AE0K were obtained. The loss of isobutene in a retro‐hydroboration reaction is the dominant pathway, which proceeds with a reverse barrier. Pyrolysis of the parent compound in a chemical reactor leads to the generation of several yet unobserved boron compounds. The ionization energies of the C4H6BN isomers 1,2‐ and 1,4‐dihydro‐1,4‐azaborinine and the C3H6BN isomer 1,2‐dihydro‐1,3‐azaborole were determined from threshold photoelectron spectra. 相似文献