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31.
Copper‐Free Sonogashira Coupling for High‐Surface‐Area Conjugated Microporous Poly(aryleneethynylene) Networks 下载免费PDF全文
Matthias Trunk Anna Herrmann Dr. Hakan Bildirir Dr. Ali Yassin Dr. Johannes Schmidt Prof. Dr. Arne Thomas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7179-7183
A modified one‐pot Sonogashira cross‐coupling reaction based on a copper‐free methodology has been applied for the synthesis of conjugated microporous poly(aryleneethynylene) networks (CMPs) from readily available iodoarylenes and 1,3,5‐triethynylbenzene. The polymerization reactions were carried out by using equimolar amounts of halogen and terminal alkyne moieties with extremely small loadings of palladium catalyst as low as 0.65 mol %. For the first time, CMPs with rigorously controlled structures were obtained without any indications of side reactions, as proven by FTIR and solid‐state NMR spectroscopy, while showing Brunauer–Emmett–Teller (BET) surface areas higher than any poly(aryleneethynylene) network reported before, reaching up to 2552 m2 g?1. 相似文献
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A simple explicit bound on the absolute values of the non-real eigenvalues of a singular indefinite Sturm-Liouville operator on the real line with the weight function sgn(·) and an integrable, continuous potential q is obtained. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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We present a method to place the eigenvalues of an electrical network towards a prescribed set of complex numbers by inserting an additional capacitance into the network. For the proof, we use recent results on rank one perturbations of regular matrix pencils. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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For regular matrix pencils 𝒜(s) = sE − A the distance to the nearest singular pencil in the Frobenius norm of the coefficients is called the distance to singularity. We derive a new lower bound for this distance by using the spectral theory of tridiagonal Toeplitz matrices. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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We consider an operator function T in a Krein space which can formally be written as (0.1)but the last term on the right of (0.1) is replaced by a relatively form‐compact perturbation of a similar form. We study relations between the operator function T, a selfadjoint operator M in some Krein space, associated with T, and an operator which can be constructed with the help of the operator function –T–1. The results are applied to a Sturm‐Liouville problem with a coefficient depending rationally on the eigenvalue parameter. 相似文献
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E. Urlaub M. Lankers I. Hartmann J. Popp M. Trunk W. Kiefer 《Fresenius' Journal of Analytical Chemistry》1996,355(3-4):329-331
The applicability of the single beam gradient force optical trap and the optical levitation technique to investigate dynamic processes in microparticles is examined. The device allows to follow chemical reactions, like the emulsion polymerization and the ester hydrolysis reaction, in single emulsion droplets. Furthermore the usability of optical traps to investigate living cells is demonstrated. 相似文献
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Quantifying DNA damage by gel electrophoresis, electronic imaging and number-average length analysis
DNA damages that can be converted to single- or double strand breaks can be quantified by separating DNA by gel electrophoresis and obtaining a quantitative image of the resulting distribution of DNA in the gel. We review the theory of this method and discuss its implementation, including the charge-coupled device (CCD) camera systems we developed to acquire images of fluorophore labeled DNA. 相似文献
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Laura Ascherl Camilla Evangelisti Prof. Dr. Thomas M. Klapötke Dr. Burkhard Krumm Julia Nafe Anian Nieder Sebastian Rest Christian Schütz Dr. Muhamed Suceska Matthias Trunk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9198-9210
An investigation of the structures and chemistry of substituted hexamethyl disiloxanes ((XCH2)3Si)2O; X=F, Cl, Br, I, N3, and ONO2) is reported. New synthetic routes to the precursor hexakis(chloromethyl)disiloxane are presented. The products with X=Cl, Br, I, and N3 were characterized by NMR, IR, and Raman spectroscopy. In addition, the single‐crystal structures of the products with X=Cl, Br, and I are discussed in detail. The compounds with X=F and ONO2 were not obtained in their pure form; instead investigations of the decomposition products revealed their conversion into intermediates. Theoretical calculations of the gas‐phase structures at the B3LYP/cc‐pVDZ, B3LYP/3‐21G, MP2/6‐31G*, and MP2/3‐21G levels of theory are used to explain the chemical and physical behavior of the compounds with X=Cl, Br, I, N3, and ONO2. A new decomposition pathway of hexakis(nitratomethyl)disiloxane is presented and is used to explain their remarkable instability. The energetic properties and values of the nitrate and azide derivatives were calculated at the CBS‐4M level of theory by using the improved EXPLO5 computer code version 6.01. 相似文献