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11.
Thierry Brotin Jacek Waluk Jean-Pierre Desvergne Henri Bouas-Laurent Josef Michl 《Photochemistry and photobiology》1992,55(3):335-347
Abstract— Linear dichroism (LD) and magnetic circular dichroism (MCD) of symmetrical dialkoxy-anthracenes and some related compounds were recorded in an attempt to elucidate electronic absorption properties and assign the nature of the lowest singlet excited state, recognized to control both the fluorescence and the photodimerization of anthracenes. The spectroscopic measurements proved that the lowest electronic transition is of the 1La type in all the compounds. The peculiar photoreactivity pattern is therefore governed by factors other than an inversion of the order of the 1La and 1Lb states and may be related to electronic density repartition on the different positions of the anthracene nucleus dictated by the position of the electron-donating substituents. 相似文献
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Sylvain Koeller Dr. Joji Kadota Dr. Frédéric Peruch Dr. Alain Deffieux Dr. Noël Pinaud Isabelle Pianet Dr. Stéphane Massip Dr. Jean‐Michel Léger Dr. Jean‐Pierre Desvergne Dr. Brigitte Bibal Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(14):4196-4205
The mechanism of the ring‐opening polymerization (ROP) of lactide catalyzed by two partner hydrogen‐bonding organocatalysts was explored. New amidoindoles 4 a , c , thioamidoindoles 4 b , d , amidobenzimidazoles 5 a , c , and thioamidobenzimidazoles 5 b , c were synthesized and used as activators of the monomer. In the solid state and in solution, compounds 4 and 5 showed a propensity for self‐association, which was evaluated. (Thio)Amides 4 and 5 do catalyze the ROP of lactide in the presence of a cocatalyst, tertiary amine 3 a or 3 b , which activates the growing polymer chain through hydrogen‐bonding. Reactions were conducted in 2–24 h at 20 °C; conversion yields ranged between 22 and 100 %. A detailed study of the intermolecular interactions undertaken between the participating species showed that, as expected, simultaneous weak hydrogen bonds do exist to activate the reagents. Moreover, interactions have been revealed between the partner catalysts 4 / 5 + 3 . ROP catalyzed by these partner activators is thus governed by multiple dynamic equilibria. The latter should be judiciously adjusted to fine‐tune the catalytic properties of (thio)amides and organocatalysts, more generally. 相似文献
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Moran N Bassani DM Desvergne JP Keiper S Lowden PA Vyle JS Tucker JH 《Chemical communications (Cambridge, England)》2006,(48):5003-5005
A novel anthracene-tagged oligonucleotide can discriminate between a fully-matched DNA target sequence and one with a single mismatching base-pair through a remarkable difference in fluorescence emission intensity upon duplex formation. 相似文献
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[reaction: see text] Irradiation of 5,12-didecyloxytetracene (1) leads to photodimers P(1) (planosymmetric) and P(2) (centrosymmetric). P(1) is characterized by naphthalene excimer fluorescence, whereas P(2) emits naphthalene monomer fluorescence. 相似文献
15.
Subramaniam Ramdas William Jones John M. Thomas Jean-Pierre Desvergne 《Chemical physics letters》1978,57(3):468-470
The photodimerization of 1,5-dichloroanthracene is discussed with particular reference to the mechanism by which the ratio of head-to-head and head-to-tail dimer differs between reaction in the solid and in solution. It is shown that in certain crystallographic space groups linear and planar imperfections will not, of themselves, produce regions of packing suitable for the formation of the “non-topochemical” dimer. A novel type of point defect which may account for the solid state reactivity is described and the extra lattice energy that is associated with this defect calculated. 相似文献
16.
Terech P Meerschaut D Desvergne JP Colomes M Bouas-Laurent H 《Journal of colloid and interface science》2003,261(2):441-450
To extend the family of 2,3-didecyloxyanthracene (DDOA, 1), an organogelator having a rodlike shape, a high polarity, and fluorescing properties, the 6,7-dichloro derivative (Cl2DDOA, 2), was designed and prepared. Compound 2 forms gels in alcohols, nitriles, and alkanes. The electronic absorption spectra of the gel show a finer structure than those of the isotropic solutions, pointing to a specific degree of packing of the molecules; such an aggregation mode is also supported by fluorescence data. The gel-to-sol temperatures (Tm) were determined as a function of gelator concentration and the corresponding enthalpies (DeltaHm) were extracted. Scattering experiments have shown that the molecular packing in aggregates of 2 organogels is less reminiscent of the crystalline state than was the situation with DDOA gels. 2 organogels in butanol are made up of 120 A radius fibers much thinner than those observed in DDOA gels (r ca. 300 A) and with rather monodisperse cross sections. In 1-octanol, dodecane, or cyclohexane, the fibrillar organogel networks involve a broader distribution of the related cross sections through anisometric sections of the fibers and/or formation of bundles. 相似文献
17.
Del Guerzo A Olive AG Reichwagen J Hopf H Desvergne JP 《Journal of the American Chemical Society》2005,127(51):17984-17985
Anthracene derivatives self-assemble into fibers with a high molecular order, as is evidenced by probing the structure with energy-trapping tetracene analogues. Efficient energy transfer processes involving tens to hundreds of donors per acceptor and high emission quantum yields are outstanding characteristics displayed in these self-assembled fibers. 相似文献
18.
Shklyarevskiy IO Jonkheijm P Christianen PC Schenning AP Meijer EW Henze O Kilbinger AF Feast WJ Del Guerzo A Desvergne JP Maan JC 《Journal of the American Chemical Society》2005,127(4):1112-1113
We report the experimental observation of magnetic field deformation of spherical nanocapsules, self-assembled from sexithiophene molecules, into oblate spheroids, confirming a long-standing theoretical prediction. The magnetically deformed objects can be trapped in a compatible organogel to make them suitable for further investigations and applications. Our results show that strong magnetic forces can be effectively used, in a contact-free manner, as a tool to control the self-organization of a whole class of functional organic molecules. 相似文献
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