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Dr. Aliaksei Putau Dr. Harald Brand Prof. Dr. Konrad Koszinowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12868-12876
Conjugate additions of organocuprates are of outstanding importance for organic synthesis. To improve our mechanistic understanding of these reactions, we have used electrospray ionization mass spectrometry for the identification of the ionic intermediates formed upon the treatment of LiCuR2 ? LiCN (R=Me, Bu, Ph) with a series of α,β‐unsaturated nitriles. Acrylonitrile, the weakest Michael acceptor included, did not afford any detectable intermediates. Fumaronitrile (FN) yielded adducts of the type Lin?1CunR2n(FN)n?, n=1–3. When subjected to fragmentation in the gas phase, these adducts were not converted into the conjugate addition products, but re‐dissociated into the reactants. In contrast, the reaction with 1,1‐dicyanoethylene furnished the products of the conjugate addition without any observable intermediates. Tri‐ and tetracyanoethylene proved to be quite reactive as well. The presence of several cyano groups in these substrates opened up reaction pathways different from simple conjugate additions, however, and led to dimerization and substitution reactions. Moreover, the gas‐phase fragmentation behavior of the species formed from these substrates indicated the occurrence of single‐electron transfer processes. Additional quantum‐chemical calculations provided insight into the structures and stabilities of the observed intermediates and their consecutive reactions. 相似文献
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Photoluminescence and optical properties of as-anodized and heat-treated at 500 °C porous alumina films formed in a 0.3 M oxalic acid at 40 V have been studied. The FTIR indicates that the oxalate ions are embedded in the anodic alumina as chelating bidentate structures and further heating up to 500 °C does not cause any change in ion coordination. The results of time-resolved spectroscopy show the presence of two luminescence centers both in the as-anodized and heat-treated anodic alumina films with lifetimes of about 0.25 and 4.0 ns. The F+-centers in anodic alumina are responsible for the luminescence peak at about 420 nm, with a lifetime of about 4.0 ns. The luminescence peak at about 480 nm, with lifetime of about 0.25 ns, can be attributed to the luminescence of carboxylate ions existing in bulk of anodic alumina. 相似文献
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Lesnyak V Wolf A Dubavik A Borchardt L Voitekhovich SV Gaponik N Kaskel S Eychmüller A 《Journal of the American Chemical Society》2011,133(34):13413-13420
A 3D metal ion assisted assembly of nanoparticles has been developed. The approach relies on the efficient complexation of cadmium ions and 5-mercaptomethyltetrazole employed as the stabilizer of both colloidal CdTe and Au nanoparticles. It enables in a facile way the formation of hybrid metal-semiconductor 3D structures with controllable and tunable composition in aqueous media. By means of critical point drying, these assemblies form highly porous aerogels. The hybrid architectures obtained are characterized by electron microscopy, nitrogen adsorption, and optical spectroscopy methods. 相似文献
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Blokhin AV Paulechka YU Strechan AA Kabo GJ 《The journal of physical chemistry. B》2008,112(14):4357-4364
Thermodynamic properties of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim]NTf2) ionic liquid have been studied by adiabatic calorimetry in the temperature range of 5 to 370 K. This compound has been found to form crystal, liquid, and glass. The temperature and enthalpy of fusion for [C(4)mim]NTf(2) have been determined to be T(fus) = 270.22 +/- 0.02 K and Delta(fus)H = 23.78 +/- 0.04 kJ.mol(-1), respectively. The heat capacity of crystalline [C(4)mim]NTf(2) in the T range of 205 to 255 K may vary by a few percent, subject to the procedure of the crystal preparation. The glass transition temperature for [C(4)mim]NTf(2) has been found to be T(g) = 181.5 +/- 0.1 K. On the basis of the results of DFT quantum chemical calculations, the experimental vibrational spectra, and the available literature data, thermodynamic properties of [C(4)mim]NTf(2) in the ideal-gas state have been calculated by the statistical thermodynamic methods. The entropy values for the gaseous compound obtained from the experimental data and the calculations are in satisfactory agreement. 相似文献
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Pukin AV Florack DE Brochu D van Lagen B Visser GM Wennekes T Gilbert M Zuilhof H 《Organic & biomolecular chemistry》2011,9(16):5809-5815
Biotinylated analogues of gangliosides GM2, GM1, GD1a and GalNAc-GD1a were synthesized in high yields using glycosyltransferases from Campylobacter jejuni. The presence of a biotin moiety in the aglycone part of these mimics allows for attachment of these materials onto various streptavidin-coated surfaces. Analysis of the interaction of biotin-appended GM1 with the B subunit of Escherichia coli heat-labile enterotoxin performed in a modified ELISA procedure shows the potential of this compound to replace the natural GM1 in toxin detection. 相似文献
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Bakavets Aliaksei Aniskevich Yauhen Ragoisha Genady Mazanik Alexander Tsyntsaru Natalia Cesiulis Henrikas Streltsov Eugene 《Journal of Solid State Electrochemistry》2021,25(12):2807-2819
Journal of Solid State Electrochemistry - Selective electrochemical transformations of bismuth interlayers in (Bi2)m(Bi2Te3)n superlattices can be of interest as a means of thermoelectric materials... 相似文献
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Khmelevskaya D. Shcherbinin D. P. Konshina E. A. Abboud M. M. Dubavik A. Gladskikh I. A. 《Optics and Spectroscopy》2018,125(5):731-734
Optics and Spectroscopy - Local fields of metal nanoparticles can change quantum dots (QDs) absorption and luminescence. In this work, we have investigated the interaction of granulated Ag NPs... 相似文献
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Ushakova E. V. Matuhina A. I. Sokolova A. V. Cherevkov S. A. Bogdanov K. V. Dubavik A. Baranov M. A. Litvin A. P. Takai K. Fedorov A. V. Baranov A. V. 《Optics and Spectroscopy》2019,127(6):1110-1116
Optics and Spectroscopy - Materials with perovskite-type crystal structure attract much attention due to their unique optical properties, such as high quantum yield of photoluminescence and high... 相似文献