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81.
Laura Parejo Dr. Mahdi Chaari Sara Santiago Dr. Gonzalo Guirado Prof. Francesc Teixidor Dr. Rosario Núñez Dr. Jordi Hernando 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):270-280
Icosahedral metallacarboranes are θ-shaped anionic molecules in which two icosahedra share one vertex that is a metal center. The most remarkable of these compounds is the anionic cobalt-based metallacarborane [Co(C2B9H11)2]−, whose oxidation-reduction processes occur via an outer sphere electron process. This, along with its low density negative charge, makes [Co(C2B9H11)2]− very appealing to participate in electron-transfer processes. In this work, [Co(C2B9H11)2]− is tethered to a perylenediimide dye to produce the first examples of switchable luminescent molecules and materials based on metallacarboranes. In particular, the electronic communication of [Co(C2B9H11)2]− with the appended chromophore unit in these compounds can be regulated upon application of redox stimuli, which allows the reversible modulation of the emitted fluorescence. As such, they behave as electrochemically-controlled fluorescent molecular switches in solution, which surpass the performance of previous systems based on conjugates of perylendiimides with ferrocene. Remarkably, they can form gels by treatment with appropriate mixtures of organic solvents, which result from the self-assembly of the cobaltabisdicarbollide-perylendiimide conjugates into 1D nanostructures. The interplay between dye π-stacking and metallacarborane electronic and steric interactions ultimately governs the supramolecular arrangement in these materials, which for one of the compounds prepared allows preserving the luminescent behavior in the gel state. 相似文献
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Abstract On radiolysis tris(acetylacetonato) cobalt(III) in aqueous solutions is found to get reduced by reaction with (1) hydrated electrons, (2) H atoms, (3) OH radicals and (4) C2H2OH radicals. The bimolecular rate constants for the first three reactions, determined by competition kinetics are: 4 × 1010, 2.3 × 109 and 4.7 × 109 M?1sec?1 respectively. Absorption spectra of the irradiated solutions indicate the formation of bis(acetylacetonato) cobalt(II) from reaction (1), but not from (3). The total cobaltous yield in air-free solutions is given byG(Co++) = 5.6 and 6.5 at pH 6.5 and 1 respectively. It appears that Geaq- ∽ H + GoH ∽ 2.8 in neutral solutions. Considerations of material balance for the primary yields of radiolysis of water suggest the possibility that the so-called independent H-atoms in neutral solutions are probably excited water molecules or ion-pairs. 相似文献
85.
The photoluminescence (PL) properties of ZrO2 have been measured at different temperatures between 7 and 300 K, using various kinds of ZrO2 specimens: bulk crystal melt-grown by a large solar furnace, thermally oxidized zirconium plate (ZrO2 film crystal on Zr ) and nanocrystals (surface area: 35–45m2/g, diameter: 20–30 nm). The results clarify the deep and shallow energy level structures in the energy gap. Reversible UV-laser-light-induced spectral changes are observed for all of the specimens in different specimen-atmospheres (vacuum and O2 gas). The results elucidate the defect-effects of the PL properties and the PL enhancement mechanism in ZrO2 nanocrystals. 相似文献
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Ji‐Xin Tian Can Peng Lei Xu Yuan Tian Zun‐Jian Zhang 《Biomedical chromatography : BMC》2013,27(6):775-783
In this report, the in vitro metabolism of Strychnos alkaloids was investigated using liquid chromatography/high‐resolution mass spectrometry for the first time. Strychnine and brucine were selected as model compounds to determine the universal biotransformations of the Strychnos alkaloids in rat liver microsomes. The incubation mixtures were separated by a bidentate‐C18 column, and then analyzed by on‐line ion trap/time‐of‐flight mass spectrometry. With the assistance of mass defect filtering technique, full‐scan accurate mass datasets were processed for the discovery of the related metabolites. The structural elucidations of these metabolites were achieved by comparing the changes in accurate molecular masses, calculating chemical component using Formula Predictor software and defining sites of biotransformation based upon accurate MSn spectral information. As a result, 31 metabolites were identified, of which 26 metabolites were reported for the first time. These biotransformations included hydroxylation, N‐oxidation, epoxidation, methylation, dehydrogenation, de‐methoxylation, O‐demethylation, as well as hydrolysis reactions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Auf der Grundlage des Zirkulations-Diffusions-Prinzips wurden zwei Trennrohre für die Hochanreicherung von Gasen enytwickelt. Als Modellgasmischungen dienten H2-N2 Kr-CH4 und Luft. Neben Wasserdampf wurden Methanol- und Äthaanoldämpfe als Treibmittel benutzt. Gute Trennungen wurden in einem nur 20 cm langen Rohr erzielt, dessen Trennspalt horizontal durch Lamellen in kleine Sektionen und durch ein Drahtdiaphragma vertikal in zwei Ringkammern geteilt wird. Drei Rohre dieses Typs wurden in einer rechteckigen Kaskadenanordnung getestet. Die Theorie des Transportes im Trennrohr sowie die Behandlung des hydrodynamischen Problems werden angegeben. Eine Anwendung des beschriebenen Trennrohres zur Isotopentrennung und zur Gashochanreicherung erscheint aussichtsreich. 相似文献
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We report here our results on the spectroscopic and elemental analysis of femtosecond (fs) laser-modified regions in polymers of polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) in the context of defect formation and emission in the visible region. Different physical and chemical models are used to explain the changes in modified regions. We found that the emission intensity, recorded from the fs-modified regions of polymers, decreased over time to a constant value. We also demonstrate that these materials are suitable for the preparation of the microstructures en route for light guiding applications. The fs laser-irradiated regions exhibited paramagnetic behavior as was confirmed from electron spin resonance studies through the formation of peroxide-type free radicals. Raman mapping was performed in the modified regions which consisted of defects and found that the modulations in intensity are predominant in the central portion of the structure compared to edges. Elemental analysis has been performed in the modified regions using field emission scanning electron microscope instrument and energy-dispersive X-ray absorption spectroscopy to estimate the percentage contents of individual elements which resulted in defect formation such as paramagnetic and optical centers. 相似文献