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81.
Niki Baccile Anna Fischer Beatriz Julián-López David Grosso Clément Sanchez 《Journal of Sol-Gel Science and Technology》2008,47(2):119-123
Core-shell and homogeneous distributions of functionalized cerium oxide nanoparticles within spray-dried mesostructured silica
spheres are achieved by modification of synthesis parameters such as the templating agent and nanoparticle capping functions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Clément Sanchez (Corresponding author)Email: |
82.
Tolosa J Romero-Nieto C Díez-Barra E Sánchez-Verdú P Rodríguez-López J 《The Journal of organic chemistry》2007,72(10):3847-3852
The efficient synthesis of new asymmetric poly(phenylenevinylene) dendritic macromolecules using a stepwise convergent-growth approach is described. By an iterative methodology that made use of the Horner-Wadsworth-Emmons (HWE) reaction, dendrons and dendrimers up to the third generation, with eight different functional groups located at the periphery, were prepared in good yields. Both the number and placement of functionalities can be accurately controlled to afford a large variety of dendritic architectures. 相似文献
83.
Hadad C Achelle S García-Martinez JC Rodríguez-López J 《The Journal of organic chemistry》2011,76(10):3837-3845
A series of 4-arylvinyl-2,6-di(pyridin-2-yl)pyrimidines have been efficiently prepared by a double cross-coupling reaction between 2,4-dichloro-6-methylpyrimidine and 2-(tributylstannyl)pyridine, followed by aldol condensation with the appropriate aromatic aldehyde substituted with electron-donating, electron-withdrawing, dendritic, or water-soluble groups. The effect of different protic and aprotic solvents on the optical absorption and emission properties of these systems was studied. Compounds with electron-donating groups display strong emission solvatochromism, suggesting the formation of an intramolecular charge-separated emitting state. The solvatochromic behavior depends not only on the solvent polarity but also on the hydrogen bonding parameters of the solvent. The effect of protonation was also studied, and the abilities of some of these molecules to function as colorimetric and luminescent pH sensors were demonstrated with dramatic color changes and luminescence switching upon the introduction of acid. 相似文献
84.
Xabier Rios Paula Moriones Jesús C. Echeverría Asunción Luquín Mariano Laguna Julián J. Garrido 《Adsorption》2011,17(3):583-593
The mild synthetic conditions provided by the sol-gel process and the versatility of the colloidal state allow for the mixing
of inorganic and organic components at the nanometre scale in virtually any ratio for the preparation of hybrid materials.
Our interest in hybrid xerogels focuses on combining their porosity with other properties to prepare optic-fibre sensors.
The specific aim of this paper is to synthesise hybrid xerogels in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane
(TEOS) as silica precursors and to investigate the effect of the MTEOS molar ratio on the structure and porous texture of
xerogels. Gelation time exponentially increased as the MTEOS molar ratio increased. Increasing the MTEOS molar ratio yielded
xerogels with lower density and lower particle size. The incorporation of MTEOS resulted in new FTIR bands at 1276 and 791 cm−1, which was attributed to vibrational modes of methyl group. The band around 1092 cm−1 associated with siloxane bonds shifted to lower wavenumbers and split into two bands. The 29Si spectra only showed the Q
n
(n=2, 3, 4) signal in xerogels with 0% MTEOS and the T
n
(n=2, 3) signal in xerogels with 100% MTEOS; hybrid xerogels showed both Q and T signals. From XRD peaks at 2θ around 9°, we inferred that xerogels (>70% MTEOS) consisted of nanocrystalline CH3–SiO3/2 species. Increasing the MTEOS molar ratio produced xerogels with lower pore volumes and lower average pore size. The integration
of methyl groups on the surface decreased the surface polarity and, in turn, the characteristic energy. 相似文献
85.
Carlos LD Ferreira RA de Zea Bermudez V Julián-López B Escribano P 《Chemical Society reviews》2011,40(2):536-549
Research on organic-inorganic hybrid materials containing trivalent lanthanide ions (Ln(3+)) is a very active field that has rapidly shifted in the last couple of years to the development of eco-friendly, versatile and multifunctional systems, stimulated by the challenging requirements of technological applications spanning domains as diverse as optics, environment, energy, and biomedicine. This tutorial review offers a general overview of the myriad of advanced Ln(3+)-based organic-inorganic hybrid materials recently synthesised, which may be viewed as a major innovation in areas of phosphors, lighting, integrated optics and optical telecommunications, solar cells, and biomedicine. 相似文献
86.
Julián Bergueiro Dr. Javier Montenegro Prof. Dr. Carlos Saá Prof. Dr. Susana López 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(44):14100-14107
An expeditious, highly efficient approach to 11‐cis‐retinoids was achieved by semihydrogenation of a readily available 11‐yne precursor through a hydrosilylation–protodesilylation protocol. The complete chemo‐, regio‐, and syn‐stereoselectivity of the method also allowed direct access to 11‐ and 12‐monodeutero‐, and 11,12‐dideutero‐11‐cis‐retinoids. The analogous trans series was not accessible by this route, and was synthesized by means of Hiyama coupling. 相似文献
87.
Laeticia Vurth Caroline Hadad Sylvain Achelle Joaquín C. García-Martinez Julián Rodríguez-López Olivier Stéphan 《Colloid and polymer science》2012,290(14):1353-1359
We report the synthesis of nanosized particles based on bio-compatible polyethylene–polypropylene glycol (pluronic) materials. In aqueous solution, mini-emulsification of pluronic with two pyrimidine chromophores leads to nanoparticles with hydrodynamic radius below 100?nm. We have demonstrated that these probes exhibit a fast and fully reversible solvatochromic behaviour from yellow to purple when decreasing the pH solution. The average acidity constant of both dyes incorporated in pluronic mainly originate from the non-substituted pyrimidine (1,3-diazine) core. The close functionalization of the pyrimidine with pyridyl groups leads to a tridentate ligand suitable for metal cations complexation. Figure
Aqueous nanoparticles of pluronic triblock copolymer incorporating pyrimidine chromophores are sensitive to pH changes: protonation of the dyes within the micelles core occurs in strong acidic aqueous media leading to purple coloration when compared to yellow colour in neutral or basic pH. This solvatochromic behaviour is fully reversible. 相似文献
88.
B.Juliá-Díaz 《中国物理C(英文版)》2009,33(12)
Within the Excited Baryon Analysis Center we have performed a dynamical coupled-channels analysis of the available p(e,e'π)N data in the region of W ≤ 1.6 GeV and Q~2≤ 1.45 (GeV/c)~2. The channels included are γN, πN, ηN, and ππN which has π△, ρN, and σN components. With the hadronic parameters of the model determined in our previous investigations of πN→πN reaction, we have found that the available data in the considered W≤1.6 GeV region can be fitted well by only adjusting the bare γ~*N→N~* helicity amplitudes for the lowest N~* states in P_(33), P_(11), S_(11) and D_(13) partial waves. The meson cloud effect, as required by the unitarity conditions, on the γ~*N→ N~* form factors are examined. 相似文献
89.
Beatriz Julián‐López Dr. Mónica Martos Dr. Natalia Ulldemolins José A. Odriozola Prof. Eloisa Cordoncillo Dr. Purificación Escribano Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(45):12426-12434
An easy solvothermal route has been developed to synthesize the first mesoporous Er2O3–TiO2 mixed oxide spherical particles composed of crystalline nanoplatelets, with high surface area and narrow pore size distribution. This synthetic strategy allows the preparation of materials at low temperature with interesting textural properties without the use of surfactants, as well as the control of particle size and shape. TEM and Raman analysis confirm the formation of nanocrystalline Er2O3–TiO2 mixed oxide. Mesoscopic ordered porosity is reached through the thermal decomposition of organic moieties during the synthetic process, thus leading to a template‐free methodology that can be extended to other nanostructured materials. High specific surface areas (up to 313 m2 g?1) and narrow pore size distributions are achieved in comparison to the micrometric material synthesized by the traditional sol–gel route. This study opens new perspectives in the development, by solvothermal methodologies, of multifunctional materials for advanced applications by improving the classical pyrochlore properties (magnetization, heat capacity, catalysis, conductivity, etc.). In particular, since catalytic reactions take place on the surface of catalysts, the high surface area of these materials makes them promising candidates for catalysts. Furthermore, their spherical morphology makes them appropriate for advanced technologies in, for instance, ceramic inkjet printers. 相似文献
90.
Numerical calculation of convergent Fresnel patterns through fast Fourier transform usually requires a large number of samples to fulfill the Nyquist sampling condition around the focus. From polynomial decomposition of the wavefront it is possible to determine which polynomial orders are the main contributors to the number of samples. This information can be used to properly modify the initial wavefront and relax the Nyquist condition thus giving a more efficient numerical algorithm. 相似文献