排序方式: 共有114条查询结果,搜索用时 15 毫秒
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11652-11655
For the first time total structure determination of homoleptic alkynyl‐protected gold nanoclusters is reported. The nanoclusters are synthesized by direct reduction of PhC≡CAu, to give Au44(PhC≡C)28 and Au36(PhC≡C)24. The Au44 and Au36 nanoclusters have fcc‐type Au36 and Au28 kernels, respectively, as well as surrounding PhC≡C‐Au‐C2(Ph)Au‐C≡CPh dimeric “staples” and simple PhC≡C bridges. The structures of Au44(PhC≡C)28 and Au36(PhC≡C)24 are similar to Au44(SR)28 and Au36(SR)24, but the UV/Vis spectra are different. The protecting ligands influence the electronic structures of nanoclusters significantly. The synthesis of these two alkynyl‐protected gold nanoclusters indicates that a series of gold nanoclusters in the general formula Aux (RC≡C)y as counterparts to Aux (SR)y can be expected. 相似文献
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Adyn Melenbacher Jasveer S. Dhindsa Joe B. Gilroy Martin J. Stillman 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15483-15487
Boron difluoride (BF2) formazanate dyes are contenders for molecular species that exhibit a large Stokes shift and bright red emission. Excitation of 3‐cyanoformazanate complexes with 10 μs wide pulses of specific wavelengths resulted in strong luminescence at 663 nm at both room temperature in solution and at 77 K in a frozen solution. Analysis of the short‐lived excitation spectrum from this luminescence shows that it arises from a vibronic manifold of a higher‐lying excited state. This dark state relaxes to the emitting state over 10 μs. TD‐DFT calculations of the two lowest‐energy excited states show that the relaxed geometries are planar for S1 but highly distorted in S2. The specific time‐ and wavelength‐dependence of the excitation profile provides a unique optical encryption capability through the comparison of emission intensities between adjacent vibronic bands only accessible in the 0–12 μs time domain. 相似文献
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W. Baumann 《Fresenius' Journal of Analytical Chemistry》1977,284(1):31-38
Zusammenfassung Die durch physikalische Grundüberlegungen gegebene theoretische Grenze in der Nachweisempfindlichkeit optischer Detektoren für die Flüssigkeits-Chromatographie wird diskutiert, für Photometer-, Fluorometer-, Refraktometer- und Polarimeterdetektoren berechnet und mit den heute erreichten Nachweisempfindlichkeiten verglichen.Vortrag im Rahmen des Mainzer Seminars über instrumentelle Analytik. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(32):10294-10298
Various fluorescence microscopy techniques require bright NIR‐emitting fluorophores with high chemical and photostability. Now, the significant performance improvement of phosphorus‐substituted rhodamine dyes (PORs) upon substitution at the 9‐position with a 2,6‐dimethoxyphenyl group is reported. The thus obtained dye PREX 710 was used to stain mitochondria in living cells, which allowed long‐term and three‐color imaging in the vis‐NIR range. Moreover, the high fluorescence longevity of PREX 710 allows tracking a dye‐labeled biomolecule by single‐molecule microscopy under physiological conditions. Deep imaging of blood vessels in mice brain has also been achieved using the bright NIR‐emitting PREX 710‐dextran conjugate. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(41):12640-12644
One‐dimensional organic structures with well‐oriented π‐aggregation, strong emission, and ease of processability are desirable for optoelectronic waveguiding devices. Herein, a strategy is developed to attain this objective by self‐assembling platinum(II) acetylides into fluorescent supramolecular polymers via cooperative mechanism. The resulting high‐molecular‐weight supramolecular polymers are capable of forming electrospun microfibers with uniform geometry and smooth surface, which enable light propagation with extremely low scattering loss (0.008 dB μm−1). With the elaborate combination of bottom‐up supramolecular polymerization and top‐down electrospinning techniques, this work offers a novel and versatile avenue toward high‐performance optical waveguiding materials. 相似文献
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Maria Alba Nicolas Pazos‐Perez Beln Vaz Pilar Formentin Moritz Tebbe Miguel A. Correa‐Duarte Pedro Granero Josep Ferr‐Borrull Rosana Alvarez Josep Pallares Andreas Fery Angel R. deLera Lluis F. Marsal Ramn A. Alvarez‐Puebla 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(25):6675-6675