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231.
Xiangfeng Luan Dr. Cristina Martín Pengfei Zhang Qian Li Dr. Isabella Anna Vacchi Prof. Lucia Gemma Delogu Prof. Yiyong Mai Dr. Alberto Bianco 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18673-18679
As an emerging member of the graphene family, structurally defined graphene nanoribbons (GNRs) have shown promising applications in various fields. The evaluation of the degradability of GNRs is particularly important for assessing the persistence level and risk of these materials in living organisms and the environment. However, there is a void in the study of the degradation of GNRs. Here, we report the degradation behavior of GNRs in the presence of human myeloperoxidase (hMPO) or treated with the photo-Fenton (PF) reaction. With the assistance of potassium hydroxide or imidazole, which facilitates the dispersion of GNRs in the aqueous solution, GNRs underwent only partial degradation after 25-hour incubation with hMPO, while, the PF reaction degraded GNRs almost completely after 120 hours. These results indicate that structurally precise GNRs can be efficiently degraded under suitable conditions, providing more opportunities for future applications in different fields. 相似文献
232.
Dr. Alberto Palazzolo Dr. Timothée Naret Dr. Marion Daniel-Bertrand David-Alexandre Buisson Dr. Simon Tricard Dr. Philippe Lesot Dr. Yannick Coppel Dr. Bruno Chaudret Dr. Sophie Feuillastre Dr. Grégory Pieters 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21065-21070
We report the dramatic impact of the addition of N-heterocyclic carbenes (NHCs) on the reactivity and selectivity of heterogeneous Ru catalysts in the context of C−H activation reactions. Using a simple and robust method, we prepared a series of new air-stable catalysts starting from commercially available Ru on carbon (Ru/C) and differently substituted NHCs. Associated with C−H deuteration processes, depending on Ru/C-NHC ratios, the chemical outcome can be controlled to a large extent. Indeed, tuning the reactivity of the Ru catalyst with NHC enabled: 1) increased chemoselectivity and the regioselectivity for the deuteration of alcohols in organic media; 2) the synthesis of fragile pharmaceutically relevant deuterated heterocycles (azine, purine) that are otherwise completely reduced using unmodified commercial catalysts; 3) the discovery of a novel reactivity for such heterogeneous Ru catalysts, namely the selective C-1 deuteration of aldehydes. 相似文献
233.
Víctor Manuel Castor-Villegas José Manuel Guevara-Vela Wilmer E. Vallejo Narváez Ángel Martín Pendás Tomás Rocha-Rinza Alberto Fernández-Alarcón 《Journal of computational chemistry》2020,41(26):2266-2277
Hydrogen bonds (HB) are arguably the most important noncovalent interactions in chemistry. We study herein how differences in connectivity alter the strength of HBs within water clusters of different sizes. We used for this purpose the interacting quantum atoms energy partition, which allows for the quantification of HB formation energies within a molecular cluster. We could expand our previously reported hierarchy of HB strength in these systems (Phys. Chem. Chem. Phys., 2016, 18 , 19557) to include tetracoordinated monomers. Surprisingly, the HBs between tetracoordinated water molecules are not the strongest HBs despite the widespread occurrence of these motifs (e.g., in ice Ih). The strongest HBs within H2O clusters involve tricoordinated monomers. Nonetheless, HB tetracoordination is preferred in large water clusters because (a) it reduces HB anticooperativity associated with double HB donors and acceptors and (b) it results in a larger number of favorable interactions in the system. Finally, we also discuss (a) the importance of exchange-correlation to discriminate among the different examined types of HBs within H2O clusters, (b) the use of the above-mentioned scale to quickly assess the relative stability of different isomers of a given water cluster, and (c) how the findings of this research can be exploited to indagate about the formation of polymorphs in crystallography. Overall, we expect that this investigation will provide valuable insights into the subtle interplay of tri- and tetracoordination in HB donors and acceptors as well as the ensuing interaction energies within H2O clusters. 相似文献
234.
Daniel Hernández-Valdés Ricardo Fernández-Terán Benjamin Probst Bernhard Spingler Roger Alberto 《Helvetica chimica acta》2020,103(10):e2000147
Reduction of CO2 to CO and H2O is a two electron/two proton process. For this process, multinuclear complexes offer advantages by concentrating reduction equivalents more efficiently than mononuclear systems. We present novel complexes with [Re(η6-C6H6)2]+ as scaffold conjugated to one or two catalytically active [Ru(dmbpy)(CO)2Cl2] subunits (dmbpy=5,5′-dimethyl-2,2′-bipyridine). The [Re(η6-C6H6)2]+ scaffold was chosen due to its very high photo- and chemical stability, as well as the multiple degrees of freedom it offers for any conjugated functionalities. High efficiency and selectivity for the reduction of CO2 to CO (over H2 or HCOOH) is reported. TONs and TOFs were found to be comparable or higher than for the catalyst subunit without the rhenium framework. Cooperativity in photo- and electrocatalysis is observed for the complex comprising two catalytic subunits. The synergistic communication between the two catalytic subunits is responsible for the observed enhancement in both photo- and electrocatalytic performance. Confirmation of electronic communication between the two [Ru(dmbpy)(CO)2Cl2] subunits as well as the elucidation of a possible mechanism was supported by electrochemistry, IR-spectroelectrochemistry and DFT studies. 相似文献
235.
Martiniano Bello Concepcin Guadarrama-Garca Rolando Alberto Rodriguez-Fonseca 《Journal of computer-aided molecular design》2020,34(3):293-303
Abnormalities in the expression levels of EGFR/HER2 are found in many different types of human cancer; therefore, the design of dual inhibitors of EGFR/HER2 is a recognized anti-cancer strategy. Some lapatinib derivatives have been previously synthesized by modification at the methylsulfonylethylaminomethylfuryl group and biologically evaluated, demonstrating that the 2i compound shows potent inhibitory activity against EGFR/HER2-overexpressing cancer cells. In the present study, we explored the structural and energetic features that guide the molecular recognition of 2i using various EGFR/HER2 states. Molecular dynamics (MD) simulation with an MMPB(GB)SA approach was used to generate the inactive EGFR/HER2–ligand complexes. Our results corroborate that slight modification of lapatinib contributes to an increase in the affinity of the 2i compound for inactive EGFR/HER2 as compared with lapatinib compound, which is in accordance with experimental results. Comparison with previous results reveals that lapatinib and its derivative bind more strongly to the inactive than the intermediate active-inactive HER2 state. Principal component analysis allowed the observation that coupling of 2i to EGFR/HER2 is linked to a reduction in the conformational mobility, which may also contribute to the improvement in affinity observed for this compound as compared with lapatinib. 相似文献
236.
Christian Knittl-Frank Iakovos Saridakis Thomas Stephens Dr. Rafael Gomes Dr. James Neuhaus Dr. Antonio Misale Dr. Rik Oost Dr. Alberto Oppedisano Prof. Dr. Nuno Maulide 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(48):10972-10975
The metal-promoted nucleophilic addition of sulfur ylides to π-systems is a well-established reactivity. However, the driving force of such transformations, elimination of a sulfide moiety, entails stoichiometric byproducts making them unfavorable in terms of atom economy. In this work, a new take on sulfur ylide chemistry is reported, an atom-economical gold(I)-catalyzed synthesis of dihydrobenzo[b]thiepines. The reaction proceeds under mild conditions at room temperature. 相似文献
237.
Dr. Viktor Pfeifer Marie Certiat Dr. Donia Bouzouita Dr. Alberto Palazzolo Sébastien Garcia-Argote Elodie Marcon David-Alexandre Buisson Dr. Philippe Lesot Prof. Laurent Maron Dr. Bruno Chaudret Dr. Simon Tricard Dr. Iker del Rosal Prof. Romuald Poteau Dr. Sophie Feuillastre Dr. Grégory Pieters 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):4988-4996
Ruthenium nanocatalysis can provide effective deuteration and tritiation of oxazole, imidazole, triazole and carbazole substructures in complex molecules using D2 or T2 gas as isotopic sources. Depending on the substructure considered, this approach does not only represent a significant step forward in practice, with notably higher isotope uptakes, a broader substrate scope and a higher solvent applicability compared to existing procedures, but also the unique way to label important heterocycles using hydrogen isotope exchange. In terms of applications, the high incorporation of deuterium atoms, allows the synthesis of internal standards for LC-MS quantification. Moreover, the efficacy of the catalyst permits, even under subatmospheric pressure of T2 gas, the preparation of complex radiolabeled drugs owning high molar activities. From a fundamental point of view, a detailed DFT-based mechanistic study identifying undisclosed key intermediates, allowed a deeper understanding of C−H (and N−H) activation processes occurring at the surface of metallic nanoclusters. 相似文献
238.
Stepan Geri Tereza Krunclova Dr. Olga Janouskova Dr. Jiri Panek Dr. Martin Hruby Daniel Hernández-Valdés Dr. Benjamin Probst Prof. Roger A. Alberto Dr. Constantin Mamat Dr. Manja Kubeil Dr. Holger Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(48):10992-11006
Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and 13C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria. 相似文献
239.
Marlon Winter Niklas Limberg Dr. Mathias A. Ellwanger Dr. Alberto Pérez-Bitrián Dr. Karsten Sonnenberg Dr. Simon Steinhauer Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):16089-16097
Trifluoromethylation of [AuF3(SIMes)] with the Ruppert–Prakash reagent TMSCF3 in the presence of CsF yields the product series [Au(CF3)xF3−x(SIMes)] (x=1–3). The degree of trifluoromethylation is solvent dependent and the ratio of the species can be controlled by varying the stoichiometry of the reaction, as evidenced from the 19F NMR spectra of the corresponding reaction mixtures. The molecular structures in the solid state of trans-[Au(CF3)F2(SIMes)] and [Au(CF3)3(SIMes)] are presented, together with a selective route for the synthesis of the latter complex. Correlation of the calculated SIMes affinity with the carbene carbon chemical shift in the 13C NMR spectrum reveals that trans-[Au(CF3)F2(SIMes)] and [Au(CF3)3(SIMes)] nicely follow the trend in Lewis acidities of related organo gold(III) complexes. Furthermore, a new correlation between the Au−Ccarbene bond length of the molecular structure in the solid state and the chemical shift of the carbene carbon in the 13C NMR spectrum is presented. 相似文献
240.
Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs – in particular, those based on cadmium chalcogenides – as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy. 相似文献