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91.
Martín N Altable M Filippone S Martín-Domenech A Martínez-Alvarez R Suarez M Plonska-Brzezinska ME Lukoyanova O Echegoyen L 《The Journal of organic chemistry》2007,72(10):3840-3846
Isoxazolino[4,5:1,2][60]- and -[70]fullerenes undergo an efficient retro-cycloaddition reaction to pristine fullerene by thermal treatment in the presence of an excess of a dienophile and Cu(II) catalysis, which can be selectively used in the presence of malonate or pyrrolidine cycloadducts. Trapping experiments using N-phenylmaleimide as dipolarophile have shown that the reaction mechanism occurs by thermal removal of the nitrile oxide 1,3-dipole, in a process which is favored by the presence of Cu(II) as the catalyst. The ESI-MS study supports the observed retro-cycloaddition process for both C60 and C70 derivatives. In contrast to previous electrochemical retro-cycloaddition processes observed in fulleropyrrolidines, isoxazolinofullerenes were stable under oxidative conditions. 相似文献
92.
Liliana Aguilar‐Castro Margarita Tlahuextl Antonio R. Tapia‐Benavides Hugo Tlahuext 《Heteroatom Chemistry》2003,14(3):247-253
N‐(p‐Toluenesulfonyl)glycine o‐phenolamide ( 3a ) and the analogous derivatives of d,l‐alanine ( 3b ), L ‐valine ( 3c ), L ‐leucine ( 3d ), and L ‐phenylalanine ( 3e ) were synthesized in yields >80% by condensation of N‐(p‐toluenesulfonyl)amino acyl chlorides with o‐aminophenol. The structure and conformation of these amides were established by NMR spectroscopy and X‐ray crystallography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:247–253, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10135 相似文献
93.
Dr. Perumal Venkatesan Dr. Margarita Cerón Dr. Enrique Pérez-Gutiérrez Armando E. Castillo Dr. Subbiah Thamotharan Fernando Robles Dr. Maxime A. Siegler Prof. M. Judith Percino 《ChemistryOpen》2019,8(4):483-496
Experimental and theoretical insights into the nature of intermolecular interactions and their effect on optical properties of 1-allyl-4-(1-cyano-2-(4-dialkylaminophenyl)vinyl)pyridin-1-ium bromide salts ( I and II ) are reported. A comparison of optical properties in solution and in the solid-state of the salts ( I and II ) with their precursors ( Ia and IIa ) is made. The experimental absorption maxima (λmax) in CHCl3 is at 528 nm for I and at 542 nm for II , and a strong bathochromic shift of ∼110 nm is observed for salts I and II compared with their precursors. The absorption bands in solid-state at ∼627 nm for I and at ∼615 nm for II that are assigned to charge transfer (CT) effect. The optical properties and single crystal structural features of I and II are explored by experimental and computational tools. The calculated λmax and the CT are in good agreement with the experimental results. The intermolecular interactions existing in the crystal structures and their energies are quantified for various dimers by PIXEL, QTAIM and DFT approaches. Three types of interactions, (i) the cation⋅⋅⋅cation interactions, (ii) cation⋅⋅⋅anion interactions and (iii) anion⋅⋅⋅anion interactions are observed. The cationic moiety is mainly destabilized by C−H⋅⋅⋅N/π and π⋅⋅⋅π interactions whereas the cation and anion moiety is predominantly stabilized by strong C−H⋅⋅⋅Br− interactions in both structures. The existence of charge transfer between cation and anion moieties in these structures is established through NBO analysis. 相似文献
94.
Martha?Margarita?Rueda René?Fulchiron Grégory?Martin Philippe?CassagnauEmail author 《Rheologica Acta》2017,56(7-8):635-648
The flow behavior of a filled suspension consisting of ferrite particles suspended in a polypropylene matrix with and without the addition of a commercial dispersant (Solplus DP310) was studied. The composites were filled with 10, 20, 30, and 40 vol.%. Both capillary and parallel disk rotational flows were employed. On the one hand, dynamic results confirm general trends found for highly concentrated systems. The higher is the filler level, the lower is the linear viscoelastic domain. When adding the dispersant agent, it was shown a larger linear viscoelastic domain, lower moduli values and thus, lower viscosity. Also, the critical strain, G′ and G′′ showed a power law dependency on the volume fraction. On the other hand, the capillary results showed no dependency of the flow properties on the die. Thus, no slip of the suspension at the wall was observed. Actually, this experimental finding elucidated that the significant decrease on viscosity produced by the addition of the dispersant agent at 40 vol.% is principally due to lubricant effects and not at all to slip contributions. The results also reveal three distinct flow regimes. Low, moderate, and high shear rates lead to different microstructure under flow. 相似文献
95.
Peter Adam Vladimir A. Andreev Margarita A. Man’ko Vladimir I. Man’ko 《Journal of Russian Laser Research》2017,38(6):491-506
We review the quantizer–dequantizer formalism of constructing symbols of the density operators and quantum observables, such as Wigner functions and tomographic-probability distributions. We present a tutorial consideration of the technique of obtaining minimal sets of dequantizers (quorum) related to the observable eigenvalues for one-qubit states. We discuss a generalization of the quantizer–dequantizer scheme on the example of spin-1/2 states. We consider the possibilities of extending the results to two-qubit systems using spin tomograms of the state density matrix. 相似文献
96.
Paola Acosta Braulio Insuasty Rodrigo Abonia Margarita Gutierrez Jairo Quiroga 《Molecular diversity》2017,21(4):943-955
An efficient route for the synthesis of novel 7-aryl and 7-spiropyrazolo[4\(^{\prime }\),3\(^{\prime }\):5,6]pyrido[2,3-d]pyrimidine derivatives is described. These compounds were obtained by a cyclocondensation reaction between pyrazolopyridinediamines 4 and aldehydes 5 or cyclic ketones 6 in the presence of acetic acid as catalyst. This procedure provides the desired compounds in good yields under a simple two-step methodology. The obtained compounds were evaluated as AChE inhibitors and showed weak AChe inhibition with \(\hbox {IC}_{50} = 115{-}470 \, \upmu \hbox {M}\). 相似文献
97.
Margarita A. Man’ko 《Journal of Russian Laser Research》2009,30(5):514-524
The entropies associated with tomographic-probability distributions describing quantum and classical states are discussed.
The inequalities for the tomographic entropies of quantum states are reviewed. Examples of both discrete variables (qudits,
spins) and continuous variables (photon quadratures, positions and momenta) are studied. 相似文献
98.
Vladimir A. Andreev Margarita A. Man’ko Vladimir I. Man’ko Nguyen Cong Thanh Nguyen Hung Son Stanislav D. Zakharov 《Journal of Russian Laser Research》2009,30(6):591-598
Tomographic probability representation is introduced for fermion fields. The states of the fermions are mapped onto the probability
distribution of discrete random variables (spin projections). The operators acting on the fermion states are described by
fermionic tomographic symbols. The product of the operators acting on the fermion states is mapped onto the star-product of
the fermionic symbols. The kernel of the star-product is obtained. The antisymmetry of the fermion states is formulated as
a specific symmetry property of the tomographic joint probability distribution associated with the states. 相似文献
99.
Patricia Lara Margarita Paneque Prof. Dr. Manuel L. Poveda Prof. Dr. Laura L. Santos Dr. José E. V. Valpuesta Verónica Salazar Dr. Ernesto Carmona Prof. Dr. Salvador Moncho Gregori Ujaque Dr. Agustí Lledós Prof. Dr. Celia Maya Dr. Kurt Mereiter Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9046-9057
Experimental and theoretical studies on equilibria between iridium hydride alkylidene structures, [(TpMe2)Ir(H){?C(CH2R)ArO }] (TpMe2=hydrotris(3,5‐dimethylpyrazolyl)borate; R=H, Me; Ar=substituted C6H4 group), and their corresponding hydride olefin isomers, [(TpMe2)Ir(H){R(H)C? C(H)OAr}], have been carried out. Compounds of these types are obtained either by reaction of the unsaturated fragment [(TpMe2)Ir(C6H5)2] with o‐C6H4(OH)CH2R, or with the substituted anisoles 2,6‐Me2C6H3OMe, 2,4,6‐Me3C6H2OMe, and 4‐Br‐2,6‐Me2C6H2OMe. The reactions with the substituted anisoles require not only multiple C? H bond activation but also cleavage of the Me? OAr bond and the reversible formation of a C? C bond (as revealed by 13C labeling studies). Equilibria between the two tautomeric structures of these complexes were achieved by prolonged heating at temperatures between 100 and 140 °C, with interconversion of isomeric complexes requiring inversion of the metal configuration, as well as the expected migratory insertion and hydrogen‐elimination reactions. This proposal is supported by a detailed computational exploration of the mechanism at the quantum mechanics (QM) level in the real system. For all compounds investigated, the equilibria favor the alkylidene structure over the olefinic isomer by a factor of between approximately 1 and 25. Calculations demonstrate that the main reason for this preference is the strong Ir–carbene interactions in the carbene isomers, rather than steric destabilization of the olefinic tautomers. 相似文献
100.
Nylon surface modification: 2. Nylon-supported composite films 总被引:1,自引:0,他引:1
Herrera-Alonso M McCarthy TJ Jia X 《Langmuir : the ACS journal of surfaces and colloids》2006,22(4):1646-1651
We have developed techniques for the introduction of reactive functional groups to nylon surfaces via site-specific reactions targeting at the naturally abundant amide repeating units on the surface. In this report, we describe the fabrication of nylon-supported composite surfaces using the most efficient modification methods we have developed. N-Alkylation with (3-glycidoxypropyl)triethoxysilane (GPTES) in the presence of potassium tert-butoxide (t-BuOK) leads to surfaces with silica-like reactivity. Subsequent chemical vapor deposition using tetrachlorosilane (SiCl4) and water results in composite films with a thin layer of silica, which was made hydrophobic by reaction with a fluorinated silane reagent. Reduction of the amide groups with borane-THF (BH3-THF) complex leads to a 69% conversion of surface amides to the corresponding secondary amine groups. Alginate was chosen as the model polyelectrolyte for the introduction of a hydrated surface layer. Because of the strong electrostatic interaction between alginate and the amine-enriched nylon surfaces, the adsorption is fast and concentration-independent (within the concentration range studied). The polysaccharide coats the surface homogeneously, without the formation of large aggregates. The amine surfaces obtained by reduction with BH3-THF ((BH3-THF)nylon-NH) and by alkylation with 2-bromoethylamine hydrobromide (BEA-HBr, (EBA-HBr)nylon-NH2) were also used to study gold deposition through electroless plating. Immobilization of a negatively charged metal complex (AuCl4(-)) was achieved through electrostatic interaction. Gold particles disperse preferentially in the bulk of (EBA-HBr)nylon-NH2 films, while they remain confined to the outer surface layer of (BH3-THF)nylon-NH films. 相似文献