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931.
S. Reinhardt B. Bernhardt R. Holzwarth S. Karpuk W. Nörtershäuser C. Novotny 《Optics Communications》2007,274(2):354-360
We report frequency measurements at the rovibronic transition P(42)1-14 (772 nm) and R(114)2-11 (735 nm) from the electronic transition of the iodine molecule 127I2 with the help of a frequency comb as a reference. By using Doppler-free saturation spectroscopy a frequency precision in the 7 × 10−10 region is reached and two iodine cells both operated at 550-600 °C are compared. To relate our results to other measurements, the absolute transition frequency of the hyperfine structure line P(148)1-14 a1 at 780 nm with an already known transition frequency was also determined. 相似文献
932.
Dr. Johannes Tucher Dr. Katrin Peuntinger Johannes T. Margraf Prof. Dr. Timothy Clark Prof. Dr. Dirk M. Guldi Prof. Dr. Carsten Streb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8716-8719
A combined experimental and theoretical study shows that the photooxidative activity of two isostructural metal oxide clusters depends on their internal templates. To this end, two halide‐templated bismuth vanadium oxide clusters [X(Bi(dmso)3)2V12O33]? (X=Cl?, Br?) are reported and fully characterized. The two clusters show similar absorption features and illustrate that bismuth incorporation results in increased visible‐light absorption. Significantly higher photooxidative activity is observed for the bromide‐templated cluster compared with the chloride‐templated one. Detailed photophysical assays and complementary DFT calculations suggest that the more efficient triplet excited state formation in the Br?‐containing cluster is the decisive step in the photocatalysis and is due to the heavy‐atom effect of the bromide. This concept can therefore open new pathways towards the optimization of photocatalytic activity in metal oxide clusters. 相似文献
933.
Dr. Ivana Nikić Iker Valle Aramburu Christine Koehler Dr. Hartmut Gillandt Dr. Edward A. Lemke Dr. Carsten Schultz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12266-12270
trans‐Cyclooctene groups incorporated into proteins via non‐canonical amino acids (ncAAs) are emerging as specific handles for bioorthogonal chemistry. Here, we present a highly improved synthetic access to the axially and the equatorially linked trans‐cyclooct‐2‐ene isomers ( 1 a , b ). We further show that the axially connected isomer has a half‐life about 10 times higher than the equatorial isomer and reacts with tetrazines much faster, as determined by stopped‐flow experiments. The improved properties resulted in different labeling performance of the insulin receptor on the surface of intact cells. 相似文献
934.
Dr. Xiao Yun Chen Rebekka Anna Bohmann Dr. Long Wang Dr. Shunxi Dong Dr. Christoph Räuber Prof. Dr. Carsten Bolm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10330-10333
In the presence of LiBr, a palladium/copper combination catalyzes dehydrogenative amidobrominations of acrylates with NH‐sulfoximines, leading to N‐vinylated products by dual NH/CH coupling, followed by oxidative enamide bromination. Mechanistically, the domino process is proposed to involve palladium(II) species as key intermediates. First synthetic applications of the products have been demonstrated. 相似文献
935.
Highly Enantioselective Intramolecular 1,3‐Dipolar Cycloaddition: A Route to Piperidino‐Pyrrolizidines
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Dr. Srinivasa Rao Vidadala Christopher Golz Prof. Dr. Carsten Strohmann Dr. Constantin‐G. Daniliuc Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2015,54(2):651-655
Enantioselective catalytic intermolecular 1,3‐dipolar cycloadditions are powerful methods for the synthesis of heterocycles. In contrast, intramolecular enantioselective 1,3‐dipolar cycloadditions are virtually unexplored. A highly enantioselective synthesis of natural‐product‐inspired pyrrolidino‐piperidines by means of an intramolecular 1,3‐dipolar cycloaddition with azomethine ylides is now reported. The method has a wide scope and yields the desired cycloadducts with four tertiary stereogenic centers with up to 99 % ee. Combining the enantioselective catalytic intramolecular 1,3‐dipolar cycloaddition with a subsequent diastereoselective intermolecular 1,3‐dipolar cycloaddition yielded complex piperidino‐pyrrolizidines with very high stereoselectivity in a one‐pot tandem reaction. 相似文献
936.
Mechanochemical Rhodium(III)‐Catalyzed CH Bond Functionalization of Acetanilides under Solventless Conditions in a Ball Mill
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Gary N. Hermann Peter Becker Prof. Dr. Carsten Bolm 《Angewandte Chemie (International ed. in English)》2015,54(25):7414-7417
In a proof‐of‐principle study, a planetary ball mill was applied to rhodium(III)‐catalyzed C? H bond functionalization. Under solventless conditions and in the presence of a minute amount of Cu(OAc)2, the mechanochemical activation led to the formation of an active rhodium species, thus enabling an oxidative Heck‐type cross‐coupling reaction with dioxygen as the terminal oxidant. The absence of an organic solvent, the avoidance of a high reaction temperature, the possibility of minimizing the amount of the metallic mediator, and the simplicity of the protocol result in a powerful and environmentally benign alternative to the common solution‐based standard protocol. 相似文献
937.
Pit van Bonn Prof. Dr. Carsten Bolm Dr. José G. Hernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2576-2580
Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide. 相似文献
938.
Dr. Alba Gigante Eline Sijbesma Dr. Pedro A. Sánchez-Murcia Prof. Xiaoyu Hu Dr. David Bier Sandra Bäcker Prof. Shirley Knauer Prof. Federico Gago Prof. Christian Ottmann Prof. Carsten Schmuck 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(13):5322-5325
We report on a stabilizer of the interaction between 14-3-3ζ and the Estrogen Receptor alpha (ERα). ERα is a driver in the majority of breast cancers and 14-3-3 proteins are negative regulators of this nuclear receptor, making the stabilization of this protein-protein interaction (PPI) an interesting strategy. The stabilizer ( 1 ) consists of three symmetric peptidic arms containing an arginine mimetic, previously described as the GCP motif. 1 stabilizes the 14-3-3ζ/ERα interaction synergistically with the natural product Fusicoccin-A and was thus hypothesized to bind to a different site. This is supported by computational analysis of 1 binding to the binary complex of 14-3-3 and an ERα-derived phosphopeptide. Furthermore, 1 shows selectivity towards 14-3-3ζ/ERα interaction over other 14-3-3 client-derived phosphomotifs. These data provide a solid support of a new binding mode for a supramolecular 14-3-3ζ/ERα PPI stabilizer. 相似文献
939.
Kristopher O. Davis Kaiyun Jiang Carsten Demberger Heiko Zunft Helge Haverkamp Dirk Habermann Winston V. Schoenfeld 《固体物理学:研究快报》2013,7(5):319-321
Emitter formation for industrial crystalline silicon (c‐Si) solar cells is demonstrated by the deposition of phosphorous‐doped silicate glasses (PSG) on p‐type monocrystalline silicon wafers via in‐line atmospheric pressure chemical vapor deposition (APCVD) and subsequent thermal diffusion. Processed wafers with and without the PSG layers have been analysed by SIMS measurements to investigate the depth profiles of the resultant phosphorous emitters. Subsequently, complete solar cells were fabricated using the phosphorous emitters formed by doped silicate glasses to determine the impact of this high‐throughput doping method on cell performance. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
940.
Kristopher O. Davis Kaiyun Jiang Marshall Wilson Carsten Demberger Heiko Zunft Helge Haverkamp Dirk Habermann Winston V. Schoenfeld 《固体物理学:研究快报》2013,7(11):942-945
Using a high throughput, in‐line atmosphere chemical vapor deposition (APCVD) tool, we have synthesized amorphous aluminum oxide (AlOx) films from precursors of trimethyl‐aluminum (TMA) and O2, yielding a maximum deposition 150 nm min–1 per wafer. For p‐type crystalline silicon (c‐Si) wafers, excellent surface passivation was achieved with the APCVD AlOx films, with a best maximum effective surface recombination velocity (Seff,max) of 8 cm/s following a standard industrial firing step. The findings could be attributed to the existence of large negative charge (Qf ≈ –3 × 1012 cm–2) and low interface defect density (Dit ≈ 4 × 1011 eV–1 cm–2) achieved by the films. This data demonstrates a high potential for APCVD AlOx to be used in high efficiency, low cost industrial solar cells. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献