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161.
Controlled Zn‐Mediated Grafting of Thin Layers of Bipodal Diazonium Salt on Gold and Carbon Substrates
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Mabel Torréns Dr. Mayreli Ortiz Prof. Dr. Anthony P. F. Turner Dr. Valerio Beni Dr. Ciara K. O'Sullivan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):671-681
A controlled, rapid, and potentiostat‐free method has been developed for grafting the diazonium salt (3,5‐bis(4‐diazophenoxy)benzoic acid tetrafluoroborate (DCOOH)) on gold and carbon substrates, based on a Zn‐mediated chemical dediazonation. The highly stable thin layer organic platforms obtained were characterized by cyclic voltammetry, AFM, impedance, XP, and Raman spectroscopies. A dediazonation mechanism based on radical formation is proposed. Finally, DCOOH was proved as a linker to an aminated electroactive probe. 相似文献
162.
Synthesis and Applications of Silyl 2‐Methylprop‐2‐ene‐1‐sulfinates in Preparative Silylation and GC‐Derivatization Reactions of Polyols and Carbohydrates
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Prof. Dr. Dean Marković Wandji Augustin Tchawou Dr. Irina Novosjolova Dr. Sylvain Laclef Dr. Dmitrijs Stepanovs Prof. Dr. Māris Turks Prof. Dr. Pierre Vogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):4196-4205
Trimethylsilyl, triethylsilyl, tert‐butyldimethylsilyl, and triisopropylsilyl 2‐methylprop‐2‐ene‐1‐sulfinates were prepared through (CuOTf)2?C6H6‐catalyzed sila‐ene reactions of the corresponding methallylsilanes with SO2 at 50 °C. Sterically hindered, epimerizable, and base‐sensitive alcohols gave the corresponding silyl ethers in high yields and purities at room temperature and under neutral conditions. As the byproducts of the silylation reaction (SO2+isobutylene) are volatile, the workup was simplified to solvent evaporation. The developed method can be employed for the chemo‐ and regioselective semiprotection of polyols and glycosides and for the silylation of unstable aldols. The high reactivity of the developed reagents is shown by the synthesis of sterically hindered per‐O‐tert‐butyldimethylsilyl‐α‐d ‐glucopyranose, the X‐ray crystallographic analysis of which is the first for a per‐O‐silylated hexopyranose. The per‐O‐silylation of polyols, hydroxy carboxylic acids, and carbohydrates with trimethylsilyl 2‐methylprop‐2‐ene‐1‐sulfinate was coupled with the GC analysis of nonvolatile polyhydroxy compounds both qualitatively and quantitatively. 相似文献
163.
Dolnik M Bánsági T Ansari S Valent I Epstein IR 《Physical chemistry chemical physics : PCCP》2011,13(27):12578-12583
We use the photosensitive chlorine dioxide-iodine-malonic acid reaction-diffusion system to study wavenumber locking of Turing patterns with spatial periodic forcing. Wavenumber-locked stripe patterns are the typical resonant structures that labyrinthine patterns exhibit in response to one-dimensional forcing by illumination when images of stripes are projected on a working medium. Our experimental results reveal that segmented oblique, hexagonal and rectangular patterns can also be obtained. However, these two-dimensional resonant structures only develop in a relatively narrow range of forcing parameters, where the unforced stripe pattern is in close proximity to the domain of hexagonal patterns. Numerical simulations based on a model that incorporates the forcing by illumination using an additive term reproduce well the experimental observations. These findings confirm that additive one-dimensional forcing can generate a two-dimensional resonant response. However, such a response is considerably less robust than the effect of multiplicative forcing. 相似文献
164.
Marvin Linnemannstöns Dr. Jan Schwabedissen Beate Neumann Dr. Hans-Georg Stammler Dr. Raphael J. F. Berger Prof. Dr. Norbert W. Mitzel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(10):2169-2173
Three 1,2-diaryltetramethyldisilanes X5C6-(SiMe2)2-C6X5 with two C6H5, C6F5, or C6Cl5 groups were studied concerning the importance of London dispersion driven interactions between their aryl groups. They were prepared from 1,2-dichlorotetramethyldisilane by salt elimination. Their structures were determined in the solid state by X-ray diffraction and for free molecules by gas electron-diffraction. The solid-state structures of the fluorinated and chlorinated derivatives are dominated by aryl–aryl interactions. Unexpectedly, Cl5C6-(SiMe2)2-C6Cl5 exists exclusively as an eclipsed syn-conformer in the gas phase with strongly distorted Si-C6Cl5 units due to strong intramolecular interactions. In contrast, F5C6-(SiMe2)2-C6F5 reveals weaker interactions. The contributions to the total interaction energy were analyzed by SAPT calculations. 相似文献
165.
Jöns KD Hafenbrak R Singh R Ding F Plumhof JD Rastelli A Schmidt OG Bester G Michler P 《Physical review letters》2011,107(21):217402
We apply external uniaxial stress to tailor the optical properties of In(x)Ga(1-x)As/GaAs quantum dots. Unexpectedly, the emission energy of single quantum dots controllably shifts to both higher and lower energies under tensile strain. Theoretical calculations using a million atom empirical pseudopotential many-body method indicate that the shifting direction and magnitude depend on the lateral extension and more interestingly on the gallium content of the quantum dots. Our experimental results are in good agreement with the underlying theory. 相似文献
166.
K. Aniskevich J. Korsgaard A. Mālmeisters J. Jansons 《Mechanics of Composite Materials》1998,34(3):213-222
The results of short-term creep tests of a layered glass fiber/polyester resin plastic in tension at angles of 90, 70, and 45° to the direction of the principal fiber orientation are presented. The applicability of the principle of time-temperature analogy for the prediction of long-term creep of the composite and its structural components is revealed. The possibility of evaluating the viscoelastic properties of the composite from the properties of structural components is shown.Presented at the 10th International Conference on the Mechanics of Composite Materials (Riga, April 20–23, 1998).Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 3, pp. 295–306, May–June, 1998. 相似文献
167.
168.
Sebastiāo C. de Almeida Aldir Brasil Jr. Luiz Amâncio M. Souza Jr. 《Results in Mathematics》2004,46(1-2):1-9
Let M be a compact, minimal 3-dimensional submanifold with constant scalar curvature R immersed in the standard sphere S3+p. In codimension 1, we know from the work that has been done on Chern’s conjecture that M is isoparametric and R = 3D0, R = 3D3 or R = 3D6. In this paper we extend this result from codimension one to compact submanifolds with a flat normal bundle and give a complete classification. 相似文献
169.
Agapie Alexandru Höns Robin Mühlenbein Heinz 《Methodology and Computing in Applied Probability》2004,6(2):181-201
We consider the finite homogeneous Markov chain induced by a class of one-dimensional asynchronous cellular automata—automata that are allowed to change only one cell per iteration. Furthermore, we confine to totalistic automata, where transitions depend only on the number of 1s in the neighborhood of the current cell. We consider three different cases: (i) size of neighborhood equals length of the automaton; (ii) size of neighborhood two, length of automaton arbitrary; and (iii) size of neighborhood three, length of automaton arbitrary. For each case, the associated Markov chain proves to be ergodic. We derive simple-form stationary distributions, in case (i) by lumping states with respect to the number of 1s in the automaton, and in cases (ii) and (iii) by considering the number of 0–1 borders within the automaton configuration. For the three-neighborhood automaton, we analyze also the Markov chain at the boundary of the parameter domain, and the symmetry of the entropy. Finally, we show that if the local transition rule is exponential, the stationary probability is the Boltzmann distribution of the Ising model. 相似文献
170.
Potassium allyltrifluoroborates underwent a bora-ene reaction with sulfur dioxide in the absence of Lewis acid catalysts to give sulfinyloxy-trifluoroborates, which subsequently undergo alkylation with electrophiles to produce sulfones in up to 91% yield. Benzyl halides and haloacetic acid derivatives can be used as the alkylation reagents while the Sanger reagent undergoes a SNAr reaction with sulfinyloxy-trifluoroborates to produce the corresponding 2,4-dinitrophenylsulfone. The developed method allows the transformation of potassium allyltrifluoroborates into allyl sulfones. 相似文献