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1.
Gabriele Albertin Stefano Antoniutti Jesús Castro Francesca Sibilla 《无机化学与普通化学杂志》2019,645(8):638-644
Imine complexes [IrCl(η5‐C5Me5){κ1‐NH=C(H)Ar}{P(OR)3}]BPh4 ( 1 , 2 ) (Ar = C6H5, 4‐CH3C6H4; R = Me, Et) were prepared by allowing chloro complexes [IrCl2(η5‐C5Me5){P(OR)3}] to react with benzyl azides ArCH2N3. Bis(imine) complexes [Ir(η5‐C5Me5){κ1‐NH=C(H)Ar}2{P(OR)3}](BPh4)2 ( 3 , 4 ) were also prepared by reacting [IrCl2(η5‐C5Me5){P(OR)3}] first with AgOTf and then with benzyl azide. Depending on the experimental conditions, treatment of the dinuclear complex [IrCl2(η5‐C5Me5)]2 with benzyl azide yielded mono‐ [IrCl2(η5‐C5Me5){κ1‐NH=C(H)Ar}] ( 5 ) and bis‐[IrCl(η5‐C5Me5){κ1‐NH=C(H)Ar}2]BPh4 ( 6 ) imine derivatives. In contrast, treatment of chloro complexes [IrCl2(η5‐C5Me5){P(OR)3}] with phenyl azide C6H5N3 gave amine derivatives [IrCl(η5‐C5Me5)(C6H5NH2){P(OR)3}]BPh4 ( 7 , 8 ). The complexes were characterized spectroscopically (IR, NMR) and by X‐ray crystal structure determination of [IrCl(η5‐C5Me5){κ1‐NH=C(H)C6H4‐4‐CH3}{P(OEt)3}]BPh4 ( 2b ). 相似文献
2.
Nicholas Favalli Gabriele Bassi Tania Zanetti Jrg Scheuermann Dario Neri 《Helvetica chimica acta》2019,102(4)
The construction of DNA‐encoded chemical libraries (DECLs) crucially relies on the availability of chemical reactions, which are DNA‐compatible and which exhibit high conversion rates for a large number of diverse substrates. In this work, we present our optimization and validation procedures for three copper and palladium‐catalyzed reactions (Suzuki cross‐coupling, Sonogashira cross‐coupling, and copper(I)‐catalyzed alkyne‐azide cycloaddition (CuAAC)), which have been successfully used by our group for the construction of large encoded libraries. 相似文献
3.
Katharina Uhlir Michele Gironda Luca Bombelli Michael Eder Nicola Aresi Gabriele Groschner Martina Griesser 《X射线光谱测定》2019,48(4):293-302
Rembrandt's painting Old Woman Praying, 1629/30, is the most valuable and exceptional work of art of the Residenzgalerie Salzburg (RGS). It is painted on a gilded copper plate with dimensions of only approximately 15 × 12 cm. The painting probably belongs to a series of three small-scale tronies, all executed on gilded copper plates. This particular picture preparation, which represents a special feature in Rembrandt's work, is quite unusual in the history of art. Previous investigations on the comparable paintings The Laughing Man, 1629/30, in the Mauritshuis, The Hague and the Self Portrait, 1630, in the National Museum, Stockholm showed that the gilding of the copper plate was applied over a lead white ground. To characterize the painting in the RGS, X-ray fluorescence (XRF) mapping was performed in a collaboration between the Research Office Residenzgalerie, Land Salzburg, the XGLab S.R.L, Milan, and the Conservation Science Department of the Kunsthistorische Museum Vienna (KHM). The results indicate a different structure for this painting than that used for The Laughing Man and the Self Portrait. The gilding was applied directly onto the copper plate, but with three areas with the gilding missing. It seems likely that in these sections, the gold was purposely removed to provide a different darker effect. XRF mapping yielded valuable insights into the structure of the painting and its technique as well as the principal pigments used for its composition. 相似文献
4.
The Adimurthi–Druet [1] inequality is an improvement of the standard Moser–Trudinger inequality by adding a -type perturbation, quantified by , where is the first Dirichlet eigenvalue of Δ on a smooth bounded domain. It is known [3], [10], [14], [19] that this inequality admits extremal functions, when the perturbation parameter α is small. By contrast, we prove here that the Adimurthi–Druet inequality does not admit any extremal, when the perturbation parameter α approaches . Our result is based on sharp expansions of the Dirichlet energy for blowing sequences of solutions of the corresponding Euler–Lagrange equation, which take into account the fact that the problem becomes singular as . 相似文献
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Paul Cowper Yu Jin Michael D. Turton Gabriele Kociok‐Khn Simon E. Lewis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(7):2610-2614
Azulenesulfonium salts may be readily prepared from the corresponding azulenes by an SEAr reaction. These azulene sulfonium salts are bench‐stable species that may be employed as pseudohalides for cross‐coupling. Specifically, their application in Suzuki–Miyaura reactions has been demonstrated with a diverse selection of coupling partners. These azulenesulfonium salts possess significant advantages in comparison with the corresponding azulenyl halides, which are known to be unstable and difficult to prepare in pure form. 相似文献
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