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151.
Skeleton Decoration of NHCs by Amino Groups and its Sequential Booster Effect on the Palladium‐Catalyzed Buchwald–Hartwig Amination
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Yin Zhang Dr. Vincent César Golo Storch Dr. Noël Lugan Dr. Guy Lavigne 《Angewandte Chemie (International ed. in English)》2014,53(25):6482-6486
A challenging synthetic modification of PEPPSI‐type palladium pre‐catalysts consisting of a stepwise incorporation of one and two amino groups onto the NHC skeleton was seen to exert a sequential enhancement of the electronic donor properties. This appears to be positively correlated with the catalytic performances of the corresponding complexes in the Buchwald–Hartwig amination. This is illustrated, for example, by the quantitative amination of 4‐chloroanisole by morpholine within 2 h at 25 °C with a 2 mol % catalyst/substrate ratio or by a significant reduction of catalytic loading (down to 0.005 mol %) for the coupling of aryl chlorides with anilines (max TON: 19 600). 相似文献
152.
Frontispiece: NMR Fingerprints of the Drug‐like Natural‐Product Space Identify Iotrochotazine A: A Chemical Probe to Study Parkinson’s Disease
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153.
Xavier Cattoën Achraf Noureddine Jonas Croissant Nirmalya Moitra Kristýna Bürglová Jana Hodačová Olivia de los Cobos Martine Lejeune Fabrice Rossignol Delphine Toulemon Sylvie Bégin-Colin Benoît P. Pichon Laurence Raehm Jean-Olivier Durand Michel Wong Chi Man 《Journal of Sol-Gel Science and Technology》2014,70(2):245-253
The combination of the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction with sol–gel processing enables the versatile preparation of sol–gel materials under different shapes with targeted functionalities through a diversity-oriented approach. In this account, the development of the CuAAC reaction under anhydrous conditions for the synthesis of sol–gel precursors and for the assembling of magnetic nanoparticles on self-assembled monolayers is related, as well as the use of the classical CuAAC methodologies for the functionalization of mesoporous silica nanoparticles and microdots arrays. Coupling CuAAC and Sol–Gel will result in simplified preparations of multifunctional materials with controlled morphologies. 相似文献
154.
Jérémy Vuilleumier Geoffrey Gaulier Raphaël De Matos Yannick Mugnier Gabriel Campargue Jean-Pierre Wolf Luigi Bonacina Sandrine Gerber-Lemaire 《Helvetica chimica acta》2020,103(1):e1900251
While chemotherapy is one of the most used treatments in oncology, the systemic administration of chemotherapeutics generally results in undesired damages to healthy tissues and cells, side effects such as severe nausea and leukopenia, and reduced efficacy due to multidrug resistance and poor target accessibility. The limitations of conventional chemotherapy formulation have prompted the development of alternative nanomaterials-based strategies to achieve targeted and stimuli sensitive payload delivery to reach optimal local drug concentration at tumor sites. In this study, the anticancer drug chlorambucil (Clb) was conjugated to the surface of silica coated lithium niobate (LNO) harmonic nanoparticles (HNPs) using a photocaging tether based on coumarin-4-yl methyl derivative. Upon laser pulsed femtosecond irradiation at 790 nm, the second harmonic emission from the metal oxide core induced the efficient release of Clb, with concomitant contribution from the nonlinear absorption of the coumarin (CM)-based moiety. 相似文献
155.
Juan-Ramón Jiménez Jana Glatz Amina Benchohra Geoffrey Gontard Lise-Marie Chamoreau Jean-François Meunier Azzedine Bousseksou Rodrigue Lescouëzec 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8166-8170
A mixed-valence {MnII3MnIIIFeII2FeIII2} cyanide-bridged molecular cube hosting a caesium cation, Cs⊂{Mn4Fe4}, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {FeII−CN−MnIII} pair into a {FeIII−CN−MnII} pair. This feature was only previously observed in the polymeric MnFe Prussian-blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials. 相似文献
156.
An Efficient RuII–RhIII–RuII Polypyridyl Photocatalyst for Visible‐Light‐Driven Hydrogen Production in Aqueous Solution
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Dr. Thibaut Stoll Dr. Marcello Gennari Dr. Jérôme Fortage Dr. Carmen E. Castillo Dr. Mateusz Rebarz Dr. Michel Sliwa Dr. Olivier Poizat Dr. Fabrice Odobel Dr. Alain Deronzier Dr. Marie‐Noëlle Collomb 《Angewandte Chemie (International ed. in English)》2014,53(6):1654-1658
The development of multicomponent molecular systems for the photocatalytic reduction of water to hydrogen has experienced considerable growth since the end of the 1970s. Recently, with the aim of improving the efficiency of the catalysis, single‐component photocatalysts have been developed in which the photosensitizer is chemically coupled to the hydrogen‐evolving catalyst in the same molecule through a bridging ligand. Until now, none of these photocatalysts has operated efficiently in pure aqueous solution: a highly desirable medium for energy‐conversion applications. Herein, we introduce a new ruthenium–rhodium polypyridyl complex as the first efficient homogeneous photocatalyst for H2 production in water with turnover numbers of several hundred. This study also demonstrates unambiguously that the catalytic performance of such systems linked through a nonconjugated bridge is significantly improved as compared to that of a mixture of the separate components. 相似文献
157.
Dr. Tao Liu Dr. Aline Nonat Dr. Maryline Beyler Dr. Martín Regueiro‐Figueroa Dr. Katia Nchimi Nono Dr. Olivier Jeannin Dr. Franck Camerel Dr. François Debaene Dr. Sarah Cianférani‐Sanglier Prof. Raphaël Tripier Dr. Carlos Platas‐Iglesias Dr. Loïc J. Charbonnière 《Angewandte Chemie (International ed. in English)》2014,53(28):7259-7263
Lanthanide complexes (Ln=Eu, Tb, and Yb) that are based on a C2‐symmetric cyclen scaffold were prepared and characterized. The addition of fluoride anions to aqueous solutions of the complexes resulted in the formation of dinuclear supramolecular compounds in which the anion is confined into the cavity that is formed by the two complexes. The supramolecular assembly process was monitored by UV/Vis absorption, luminescence, and NMR spectroscopy and high‐resolution mass spectrometry. The X‐ray crystal structure of the europium dimer revealed that the architecture of the scaffold is stabilized by synergistic effects of the Eu? F? Eu bridging motive, π stacking interactions, and a four‐component hydrogen‐bonding network, which control the assembly of the two [EuL] entities around the fluoride ion. The strong association in water allowed for the luminescence sensing of fluoride down to a detection limit of 24 nM . 相似文献
158.
Essential oils in combination and their antimicrobial properties 总被引:1,自引:0,他引:1
Essential oils (EOs) have been long recognized for their antibacterial, antifungal, antiviral, insecticidal and antioxidant properties. They are widely used in medicine and the food industry for these purposes. The increased interest in alternative natural substances is driving the research community to find new uses and applications of these substances. EOs and their components show promising activities against many food-borne pathogens and spoilage microorganisms when tested in vitro. In food systems, higher concentrations of EOs are needed to exert similar antibacterial effects as those obtained in in vitro assays. The use of combinations of EOs and their isolated components are thus new approaches to increase the efficacy of EOs in foods, taking advantage of their synergistic and additive effects. The purpose of this review is to provide an overview on the antimicrobial efficacy of these combinations. A survey of the methods used for the determination of the interactions and mechanisms involved in the antimicrobial activities of these combinations are also reported. 相似文献
159.
160.
We perform numerical simulations of hexagonal quantum dots of AlGaN semiconductors. We show that the competition between surface mass diffusion and evaporation rules the morphology of the quantum dots. The system displays three different behaviors: presence of separated islands without a wetting layer, islands dissolving into the wetting layer, or islands that do not evolve. The first behavior is of special interest because its optoelectrical properties are significantly improved in comparison with quantum dots with a wetting layer. 相似文献