排序方式: 共有108条查询结果,搜索用时 15 毫秒
41.
Arnaud de Zordo-Banliat Dr. Kevin Grollier Jordan Vigier Dr. Erwann Jeanneau Dr. Guillaume Dagousset Dr. Bruce Pegot Dr. Emmanuel Magnier Dr. Thierry Billard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202299
Trifluorometylselenolation via C−H activation is barely described in literature. In particular, no such vinylic functionalization has been yet described. Herein, a palladium-catalyzed trifluoromethylselenolation of vinylic C−H bonds is described. The 5-methoxy-8-aminoquinoline has been used as auxiliary directing group to perform this reaction. The reaction gives excellent yields with α-substituted compounds whatever the substituents and a microwave activation can be used to accelerate the reaction. With β-substituted substrates lower yields, but still satisfactory, are obtained. This methodology was also successfully extended to other fluoroalkylselenyl groups. 相似文献
42.
1,1-Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1-cyanomethyl-1,1-dimethylhydrazinium bromide ([(CH3)2N(CH2CN)NH2]Br, 1 ). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH3)2N(CH2CN)NH2]+ cation and nitrate ( 2 ), perchlorate ( 3 ), azide ( 4 ), 5-aminotetrazolate ([H2N-CN4]−, 5 ), 5,5′-azobistetrazolate ([N4C-NN-CN4]2−, 7 ), and picrate ( 8 ) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH3)2N(CH2CN)NH2]+ cation in compounds 1 , 3 , and 8 and that of sodium 5,5′-azobistetrazolate octahydrate (NaZT⋅8 H2O) were solved by X-ray diffraction techniques. The hydrogen-bonding networks found in the structure of salts 1 , 3 , 8 , and NaZT⋅8 H2O are described using graph-set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2 , 3 , 4 , 5 , 6 , 7 , 8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application. 相似文献
43.
44.
Erwann Bocquillon Vincent Freulon François D. Parmentier Jean‐Marc Berroir Bernard Plaçais Claire Wahl Jérome Rech Thibaut Jonckheere Thierry Martin Charles Grenier Dario Ferraro Pascal Degiovanni Gwendal Fève 《Annalen der Physik》2014,526(1-2):1-30
The edge channels of the quantum Hall effect provide one dimensional chiral and ballistic wires along which electrons can be guided in an optics‐like setup. Electronic propagation can then be analyzed using concepts and tools derived from optics. After a brief review of electron optics experiments performed using stationary current sources which continuously emit electrons in the conductor, this paper focuses on triggered sources, which can generate on‐demand a single particle state. It first outlines the electron optics formalism and its analogies and differences with photon optics and then turns to the presentation of single electron emitters and their characterization through the measurements of the average electrical current and its correlations. This is followed by a discussion of electron quantum optics experiments in the Hanbury‐Brown and Twiss geometry where two‐particle interferences occur. Finally, Coulomb interactions effects and their influence on single electron states are considered. 相似文献
45.
The nanometric mixed tin-titanium oxide doped with a M(5+) cation was recently shown as a promising thermoelectric material. We report here synthesis of novel molecular precursors for above material using a convenient approach of reacting a metal chloride with a metal alkoxide. Heterometallic complexes with simple addition formula [(EtOH)(2)(OEt)(2)Ti(μ-OEt)(2)SnCl(4)] (1·EtOH) and [(EtOH)(OEt)(3)Ta(μ-OEt)(2)SnCl(4)] (2) were isolated in quantitative yield, which on recrystallization from isopropanol afforded mixed-alkoxide complexes [(Pr(i)OH)(2)(OPr(i))(2)Ti(μ-OEt)(2)SnCl(4)] (3) and [(Pr(i)OH)(OPr(i))(3)Ta(μ-OEt)(2)SnCl(4)] (4), respectively, thus indicating the robustness of the heterometallic M(μ-OEt)(2)Sn core in the solution phase. Facile conversion of these precursors to halide-free spinodal form of Ta(5+)-doped TiO(2)-SnO(2) as a potential thermoelectric material is reported. 相似文献
46.
Direct Synthesis of Hexagonal NaGdF4 Nanocrystals from a Single‐Source Precursor: Upconverting NaGdF4:Yb3+,Tm3+ and Its Composites with TiO2 for Near‐IR‐Driven Photocatalysis
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ying Chen Dr. Shashank Mishra Dr. Gilles Ledoux Dr. Erwann Jeanneau Marlene Daniel Prof. Jinlong Zhang Prof. Stéphane Daniele 《化学:亚洲杂志》2014,9(9):2415-2421
A novel single‐source precursor NaGd(TFA)4(diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide‐doped upconverting nanocrystals (NCs) that convert near‐infrared radiation into shorter‐wavelength UV/visible light. These NCs were then used to prepare well‐characterized TiO2@NaGdF4:Yb3+,Tm3+ nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented. 相似文献
47.
Bouhrara M Jeanneau E Veyre L Copéret C Thieuleux C 《Dalton transactions (Cambridge, England : 2003)》2011,40(12):2995-2999
Gold(I) N-heterocyclic carbene complexes (Au-NHC) with symmetric (bis-benzyl, -propyl and -mesityl substituents) and dissymmetric (mesityl and alkyl--benzyl or propyl--substituents) NHC ligands were synthesized and tested as catalysts for the addition of methanol to 3-hexyne, as a representative internal alkyne. While symmetric ones--bis-alkyl (propyl or benzyl) or bis-mesityl systems--displayed low activity, dissymmetric Au-NHC systems with one alkyl (benzyl or propyl) and one mesityl groups on the NHC unit were unexpectedly highly active with rates and turnover numbers up to 294,000 h(-1) and 800,000 mol.mol(Au)(-1). 相似文献
48.
Sebastien NoelHui Ren Tao TuErwann Jeanneau Caroline FélixFlorent Perret Francis VocansonChristophe Bucher Guy RoyalIsabelle Bonnamour Ulrich Darbost 《Tetrahedron letters》2012,53(35):4648-4650
A new calix[4]dicyano-diimidazole ligand was prepared in two steps from a de-tert-butylated calix[4]arene. The corresponding Cu (I) complex was found to be remarkably stable. The X-ray structure of the latter revealed a mixture of both monomeric-mononuclear and dimeric-dinuclear complexes. Detailed investigations on this copper complex, involving NMR (VT and DOSY), Infra-red, and MS analyses, demonstrated that the dimeric-dinuclear complexe does not exist in solution. Despite the presence of two cyano binding groups on the calixarene platform, every attempts to isolate a stable Cu(II) complex failed. 相似文献
49.
Marie-Christine DuclosYuttapong Singjunla Christelle PetitAlain Favre-Réguillon Erwann JeanneauFlorence Popowycz Estelle MétayMarc Lemaire 《Tetrahedron letters》2012,53(45):5984-5986
P-Chirogenic monodentate binaphthyl phosphines were prepared in five steps from enantiomerically pure BINOL. This approach supposes the utilization of two methods previously developed in our group, the formation of secondary phosphine oxide, and the reduction of tertiary phosphine oxide using the association of tetramethyldisiloxane and Ti(OiPr)4. During the last reduction step, only the formation of the more stable diastereoisomer was observed. This product was employed as a ligand for the palladium catalyzed hydrosilylation of styrene to afford the corresponding alcohol with high yield and enantiomeric excess. 相似文献
50.
Raphael Recht Lysiane Omhover-Fougy Valérie Stahl Erwann Hamon 《Magnetic resonance in chemistry : MRC》2022,60(7):719-729
Numerous predictive microbiology models have been proposed to describe bacterial population behaviors in foodstuffs. These models depict the growth kinetics of particular bacterial strains based on key physico-chemical parameters of food matrices and their storage temperature. In this context, there is a prominent issue to accurately characterize these parameters, notably pH, water activity (aw), and NaCl and organic acid concentrations. Usually, all these product features are determined using one destructive analysis per parameter at macroscale (>5 g). Such approach prevents an overall view of these characteristics on a single sample. Besides, it does not take into account the intra-product microlocal variability of these parameters within foods. Nuclear magnetic resonance (NMR) is a versatile non-invasive spectroscopic technique. Experiments can be recorded successively on a same collected sample without damaging it. In this work, we designed a dedicated NMR approach to characterize the microenvironment of foods using 10-mg samples. The multiparametric mesoscopic-scale approach was validated on four food matrices: a smear soft cheese, cooked peeled shrimps, cold-smoked salmon, and smoked ham. Its implementation in situ on salmon fillets enabled to observe the intra-product heterogeneity and to highlight the impact of process on the spatial distribution of pH, NaCl, and organic acids. This analytical development and its successful application can help address the shortcomings of monoparametric methods traditionally used for predictive microbiology purposes. 相似文献