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311.
Maximilian Joost Dr. Pauline Gualco Dr. Yannick Coppel Dr. Karinne Miqueu Dr. Christos E. Kefalidis Dr. Laurent Maron Dr. Abderrahmane Amgoune Dr. Didier Bourissou 《Angewandte Chemie (International ed. in English)》2014,53(3):747-751
Oxidative addition plays a major role in transition‐metal catalysis, but this elementary step remains very elusive in gold chemistry. It is now revealed that in the presence of GaCl3, phosphine gold chlorides promote the oxidative addition of disilanes at low temperature. The ensuing bis(silyl) gold(III) complexes were characterized by quantitative 31P and 29Si NMR spectroscopy. Their structures (distorted Y shape) and the reaction profile of σ(Si? Si) bond activation were analyzed by DFT calculations. These results provide evidence for the intermolecular oxidative addition of σ(Si? Si) bonds to gold and open promising perspectives for the development of new gold‐catalyzed redox transformations. 相似文献
312.
A Cationic Zinc Hydride Cluster Stabilized by an N‐Heterocyclic Carbene: Synthesis,Reactivity, and Hydrosilylation Catalysis 下载免费PDF全文
Dr. Arnab Rit Dr. Alessandro Zanardi Dr. Thomas P. Spaniol Prof. Dr. Laurent Maron Prof. Dr. Jun Okuda 《Angewandte Chemie (International ed. in English)》2014,53(48):13273-13277
The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4(THF)](BPh4)2 ( 1 ) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Brønsted acid or by addition of the putative zinc dication [(IMes)Zn(THF)]2+. A triply bridged thiophenolato complex 2 was formed upon oxidation of 1 with PhS? SPh. Protonolysis of 1 by methanol or water gave the corresponding trinuclear dicationic derivatives. At ambient temperature, 1 catalyzed the hydrosilylation of aldehydes, ketones, and nitriles. Carbon dioxide was also hydrosilylated under forcing conditions when using (EtO)3SiH, giving silylformate as the main product. 相似文献
313.
Hussein Awada Hussein Medlej Sylvie Blanc Marie‐Hélène Delville Roger C. Hiorns Antoine Bousquet Christine Dagron‐Lartigau Laurent Billon 《Journal of polymer science. Part A, Polymer chemistry》2014,52(1):30-38
We demonstrate an efficient strategy to anchor poly(3‐hexylthiophene) (P3HT) onto zinc oxide (ZnO) surfaces. Synthesis of a novel triethoxysilane‐terminated regioregular P3HT is herein reported and supported by thorough characterization. Three triethoxysilane‐terminated P3HTs of different molar masses were prepared via a hydrosilylation reaction from allyl‐terminated P3HT. MALDI‐TOF and 1H NMR were performed to characterize the polymer and show that around 80% of the chains are end‐functionalized. These polymers were then grafted onto the ZnO nanorods to create a macromolecular self‐assembled monolayer. This versatile technique could be subsequently applied to different metal oxide surfaces, such as silicon, titanium, or indium‐tin oxide, and represents a new one‐pot strategy based on triethoxysilane coupling reaction. Importantly, the influence of the molar mass on the grafting density and the polymer shell thickness was studied via thermo gravimetric analysis and transmission electron microscopy. The optical properties of the hybrid materials were determined by UV–visible absorption and photoluminescence to show a quenching effect of P3HT fluorescence by ZnO when grafted. This electronic transfer associated with an improved miscibility of the ZnO@P3HT, makes these hybrid materials suitable candidates for photovoltaic applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 30–38 相似文献
314.
Milica Sentic Stéphane Arbault Laurent Bouffier Dragan Manojlovic Alexander Kuhn Neso Sojic 《Chemical science》2015,6(8):4433-4437
Among luminescence techniques, electrogenerated chemiluminescence (ECL) provides a unique level of manipulation of the luminescent process by controlling the electrochemical trigger. Despite its attractiveness, ECL is by essence a 2D process where light emission is strictly confined to the electrode surface. To overcome this intrinsic limitation, we added a new spatial dimension to the ECL process by generating 3D ECL at the level of millions of micro-emitters dispersed in solution. Each single object is addressed remotely by bipolar electrochemistry and they generate collectively the luminescence in the bulk. Therefore, the entire volume of the solution produces light. To illustrate the generality of this concept, we extended it to a suspension of multi-walled carbon nanotubes where each one acts as an individual ECL nano-emitter. This approach enables a change of paradigm by switching from a surface-limited process to 3D electrogenerated light emission. 相似文献
315.
Silke C. Wenzel Holger Hoffmann Jidong Zhang Laurent Debussche Sabine Haag‐Richter Michael Kurz Frederico Nardi Peer Lukat Irene Kochems Heiko Tietgen Dietmar Schummer Jean‐Paul Nicolas Loreley Calvet Valerie Czepczor Patricia Vrignaud Agnes Mühlenweg Stefan Pelzer Rolf Müller Mark Brnstrup 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(51):15781-15785
316.
Hussein Awada Leila Mezzasalma Sylvie Blanc Delphine Flahaut Christine Dagron‐Lartigau Joël Lyskawa Patrice Woisel Antoine Bousquet Laurent Billon 《Macromolecular rapid communications》2015,36(16):1486-1491
The functionalization of zinc oxide (ZnO) nanoparticles by poly(3‐hexylthiophene) (P3HT) brush is completed by the combination of a mussel inspired biomimetic anchoring group and Huisgen cyclo‐addition “click chemistry.” Herein, the direct coupling of an azide modified catechol derivative with an alkyne end‐functionalized P3HT is described. This macromolecular binding agent is used to access core@corona ZnO@P3HT with a stable and homogeneous conjugated organic corona. Preliminary photoluminescence measurement proves an efficient electron transfer from the donor P3HT to the acceptor ZnO nanoparticles upon grafting, thus demonstrating the potential of such a combination in organic electronics.
317.
318.
Electrogenerated Chemiluminescence of Cationic Triangulene Dyes: Crucial Influence of the Core Heteroatoms 下载免费PDF全文
Dr. Catherine Adam Antoine Wallabregue Haidong Li Jérôme Gouin Dr. Rémi Vanel Stéphane Grass Dr. Johann Bosson Dr. Laurent Bouffier Prof. Jérôme Lacour Prof. Neso Sojic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19243-19249
Trianguleniums are fascinating conjugated hexacyclic cations that exhibit interesting electronic and optical properties. Herein, the electrogenerated chemiluminescence (ECL) emission of this family of fluorescent dyes is reported for the first time. Redox behavior and fluorescence properties of eight cationic triangulene luminophores with different heteroatom patterns in the core structure and various pending substituents were examined to rationalize the ECL. Clearly, the more electron‐rich the carbocation, the more efficient the corresponding ECL; two very distinct classes of triangulenes can be drawn from these studies by using an ECL wall sufficiency formalism. 相似文献
319.
Dr. Graeme J. Stasiuk Dr. Florencia Minuzzi Dr. Myra Sae‐Heng Charlotte Rivas Dr. Hans‐Paul Juretschke Dr. Lorenzo Piemonti Dr. Peter R. Allegrini Dr. Didier Laurent Andrew R. Duckworth Prof. Andrew Beeby Prof. Guy A. Rutter Prof. Nicholas J. Long 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5023-5033
Despite the contribution of changes in pancreatic β‐cell mass to the development of all forms of diabetes mellitus, few robust approaches currently exist to monitor these changes prospectively in vivo. Although magnetic‐resonance imaging (MRI) provides a potentially useful technique, targeting MRI‐active probes to the β cell has proved challenging. Zinc ions are highly concentrated in the secretory granule, but they are relatively less abundant in the exocrine pancreas and in other tissues. We have therefore developed functional dual‐modal probes based on transition‐metal chelates capable of binding zinc. The first of these, Gd ?1 , binds ZnII directly by means of an amidoquinoline moiety (AQA), thus causing a large ratiometric Stokes shift in the fluorescence from λem=410 to 500 nm with an increase in relaxivity from r1=4.2 up to 4.9 mM ?1 s?1. The probe is efficiently accumulated into secretory granules in β‐cell‐derived lines and isolated islets, but more poorly by non‐endocrine cells, and leads to a reduction in T1 in human islets. In vivo murine studies of Gd ?1 have shown accumulation of the probe in the pancreas with increased signal intensity over 140 minutes. 相似文献
320.
Production of the Bengamide Class of Marine Natural Products in Myxobacteria: Biosynthesis and Structure–Activity Relationships 下载免费PDF全文
Dr. Silke C. Wenzel Dr. Holger Hoffmann Dr. Jidong Zhang Dr. Laurent Debussche Dr. Sabine Haag‐Richter Dr. Michael Kurz Dr. Frederico Nardi Dr. Peer Lukat Irene Kochems Dr. Heiko Tietgen Prof. Dr. Dietmar Schummer Jean‐Paul Nicolas Dr. Loreley Calvet Dr. Valerie Czepczor Dr. Patricia Vrignaud Dr. Agnes Mühlenweg Priv.‐Doz. Dr. Stefan Pelzer Prof. Dr. Rolf Müller Prof. Dr. Mark Brönstrup 《Angewandte Chemie (International ed. in English)》2015,54(51):15560-15564
The bengamides, sponge‐derived natural products that have been characterized as inhibitors of methionine aminopeptidases (MetAPs), have been intensively investigated as anticancer compounds. We embarked on a multidisciplinary project to supply bengamides by fermentation of the terrestrial myxobacterium M. virescens, decipher their biosynthesis, and optimize their properties as drug leads. The characterization of the biosynthetic pathway revealed that bacterial resistance to bengamides is conferred by Leu 154 of the myxobacterial MetAP protein, and enabled transfer of the entire gene cluster into the more suitable production host M. xanthus DK1622. A combination of semisynthesis of microbially derived bengamides and total synthesis resulted in an optimized derivative that combined high cellular potency in the nanomolar range with high metabolic stability, which translated to an improved half‐life in mice and antitumor efficacy in a melanoma mouse model. 相似文献