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31.
Cycloadditions of chiral pyrroline N-oxides to levoglucosenone (1) and isolevoglucosenone (2) proceed with a high level of double asymmetric induction. Partial kinetic resolutions (KR) of both enantiomers of a racemic nitrone 3 were achieved, and a parallel kinetic resolution (PKR) experiment allowed the stereoselective divergent synthesis of two quasienantiomeric imino-C-disaccharide precursors. 相似文献
32.
Solid-State Near-Infrared Circularly Polarized Luminescence from Chiral YbIII-Single-Molecule Magnet
Bertrand Lefeuvre Carlo Andrea Mattei Dr. Jessica Flores Gonzalez Dr. Frédéric Gendron Dr. Vincent Dorcet Dr. François Riobé Dr. Claudia Lalli Dr. Boris Le Guennic Prof. Olivier Cador Dr. Olivier Maury Prof. Stéphan Guy Dr. Amina Bensalah-Ledoux Dr. Bruno Baguenard Dr. Fabrice Pointillart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(26):7362-7366
A field-induced chiral YbIII Single-Molecule Magnet (SMM) displayed an unprecedented near-infrared circularly polarized luminescence (NIR-CPL) in the solid-state. The bridging bis(1,10-phenantro[5,6b])tetrathiafulvalene triad ( L ) allowed an efficient sensitization of the NIR 2F5/2→2F7/2 emission while the NIR-CPL is associated to the f-f transitions of the YbIII ion bearing chiral β-diketonate derived-camphorate ancillary ligands. 相似文献
33.
Lalli Jokelainen Tanja Meski Antero Lindberg Josep M. Soler Marja Siitari-Kauppi Andrew Martin Jost Eikenberg 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2153-2161
Spent nuclear fuel repository safety evaluation today requires both laboratory and in situ field work in order to assess the parameters affecting the sorption and diffusion of radionuclides. Recent investigations at the Grimsel test site suggest that non-conservative errors in transport properties derived from laboratory scale experiments can lead to over-conservative estimates of matrix diffusion depths. As a result, the geosphere’s capability to retain radionuclides may be underestimated. In this study the in situ diffusion and the sorption of 134Cs and 22Na into granodiorite were determined using gamma spectroscopy. Autoradiography was used to reveal the minerals into which the radionuclides were sorbed. A rock sample was obtained from the Grimsel underground in situ diffusion test site in Switzerland. In the in situ test, a solution containing several different radionuclides was circulated continuously in a packed-off injection hole for two years and three months in order to study diffusion of the radionuclides into the surrounding bedrock. The gamma measurements show that in the course of the experiment 134Cs diffused 2.5 cm and 22Na 10 cm into the rock matrix, respectively. Caesium was found to have sorbed on mafic minerals biotite and chlorite. Results of this study were used in order to calculate an in situ effective diffusion coefficient for caesium and sodium in Grimsel granodiorite. 相似文献
34.
The photochemical cis-trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2':6',2'-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(ii) ions, and forming the [Fe(vpytpy)(2)](2+) complex. The strategy of "freezing" the cis-trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis-cis, cis-trans and trans-trans iron(ii) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis-cis and cis-trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation. 相似文献
35.
Alix A Lalli C Retailleau P Masson G 《Journal of the American Chemical Society》2012,134(25):10389-10392
Metal-free chiral phosphoric acids and chiral calcium phosphates both catalyze highly enantio- and diastereoselective electrophilic α-bromination of enecarbamates to provide an atom-economical synthesis of enantioenriched vicinal haloamines. Either enantiomer can be formed in good yield with excellent diastereo- and enantioselectivity simply by switching the catalyst from a phosphoric acid to its calcium salt. 相似文献
36.
Lalli PM Iglesias BA Toma HE de Sa GF Daroda RJ Silva Filho JC Szulejko JE Araki K Eberlin MN 《Journal of mass spectrometry : JMS》2012,47(6):712-719
Travelling wave ion mobility mass spectrometry (TWIM-MS) with post-TWIM and pre-TWIM collision-induced dissociation (CID) experiments were used to form, separate and characterize protomers sampled directly from solutions or generated in the gas phase via CID. When in solution equilibria, these species were transferred to the gas phase via electrospray ionization, and then separated by TWIM-MS. CID performed after TWIM separation (post-TWIM) allowed the characterization of both protomers via structurally diagnostic fragments. Protonated aniline (1) sampled from solution was found to be constituted of a ca. 5:1 mixture of two gaseous protomers, that is, the N-protonated (1a) and ring protonated (1b) molecules, respectively. When dissociated, 1a nearly exclusively loses NH(3) , whereas 1b displays a much diverse set of fragments. When formed via CID, varying populations of 1a and 1b were detected. Two co-existing protomers of two isomeric porphyrins were also separated and characterized via post-TWIM CID. A deprotonated porphyrin sampled from a basic methanolic solution was found to be constituted predominantly of the protomer arising from deprotonation at the carboxyl group, which dissociates promptly by CO(2) loss, but a CID-resistant protomer arising from deprotonation at a porphyrinic ring NH was also detected and characterized. The doubly deprotonated porphyrin was found to be constituted predominantly of a single protomer arising from deprotonation of two carboxyl groups. 相似文献
37.
FORCEDOSCILLATIONSOFHYPERBOLICDIFFERENTIALEQUATIONSWITHDEVIATINGARGUMENTSCUIBAOTONG(崔宝同)(BinzhouNormalCollege,Binzhou256604,C... 相似文献
38.
Oliveira FF dos Santos MR Lalli PM Schmidt EM Bakuzis P Lapis AA Monteiro AL Eberlin MN Neto BA 《The Journal of organic chemistry》2011,76(24):10140-10147
An acetate anion bearing an imidazolium cation as its charge tag was reacted with M(OAc)(2) complexes (where M = Ni, Cu, and Pd; in situ reaction) to form members of a new class of charge-tagged metal complexes. The formation of these unprecedented precatalysts with potential for cross-coupling reactions was confirmed by electrospray ionization (and tandem) mass spectrometry. The catalytic performance of the palladium complex was tested in Heck and Suzuki cross-coupling reactions, often with superior activity and yields as compared with Pd(OAc)(2). 相似文献
39.
40.
Previous studies have reported promising antimicrobial efficacy for the essential oils and solvent extracts of several indigenous Pelargonium species. This study aimed to determine if any pharmacological interaction (e.g. synergism or antagonism) exists between the volatile and non-volatile components when the different fractions were investigated. The antimicrobial activity of the following fractions were tested; the essential oil prepared by hydrodistillation (EO), non-volatile fraction (NV), prepared by extraction of plant material remaining in the distilling apparatus (having no or negligible volatile constituents) and solvent extracts prepared from fresh (FC) and dried (DC) plant material containing both volatile and non-volatile constituents. Pelargonium quercifolium oil was dominated by p-cymene (42.1%) and viridiflorol (16.9%), while P. graveolens and P. tomentosum oil had high levels of isomenthone (84.0 and 58.8%, respectively). Menthone was noted as a major constituent in the P. tomentosum EO sample. It was evident from the results that the presence of volatile constituents in the three species; P. graveolens, P. quercifolium and P. tomentosum is generally not a pre-requisite for antimicrobial activity. The most significant variations of antimicrobial activity were noted for P. tomentosum where poorer activity was noted for the FC and EO fractions against Bacillus cereus and Candida albicans. Studies on Staphylococcus aureus, however, showed the converse, where best activity was noted for the FC fraction (3.0 mg/mL). For P. quercifolium, the DC fraction indicated a notable increase in anti-staphylococcal activity (2.0 mg/mL) when compared with the FC (8.0 mg/mL) and EO (16.0 mg/mL) fractions. For P. tomentosum, the FC fraction indicated much lower antimicrobial activity (against both B. cereus and C. albicans) when compared with all other fractions, suggesting that the essential oils may impact negatively on the antimicrobial activity when tested against these two pathogens. 相似文献