排序方式: 共有49条查询结果,搜索用时 31 毫秒
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García Ruano JL Gamboa AE Gutiérrez LG Martín Castro AM Rodríguez Ramos JH Yuste F 《Organic letters》2000,2(6):733-736
A new kind of chiral dienophiles, cyclic vinyl-p-tolylsulfilimines (2a and 2b), were obtained from the corresponding (Z)-sulfinylacrylonitriles with HBF(4) and methanol. The asymmetric Diels-Alder reaction of optically pure 2a with cyclopentadiene under mild thermal or catalyzed conditions afforded only the endo-4a adduct with complete endo and pi-facial selectivities. The ability of the sulfilimine moiety to enhance the dienophilic reactivity of the double bond is similar to that of the sulfinyl group. 相似文献
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Abdel-Shafi AA Bourdelande JL Ali SS 《Dalton transactions (Cambridge, England : 2003)》2007,(24):2510-2516
Photophysical properties in dilute acetonitrile solution are reported for a number of iridium(III) and rhenium(I) complexes. The nature of the lowest excited state of the complexes under investigation is either metal-to-ligand charge transfer ((3)MLCT) or a ligand centred ((3)LC) state. Rate constants, k(q), for quenching of the lowest excited states by molecular oxygen are in the range 1.5 x 10(8) to 1.4 x 10(10) M(-1) s(-1). Efficiency of singlet oxygen production, f(Delta)(T), following oxygen quenching of the lowest excited states of these complexes, are in the range of 0.27-1.00. The rate constants and the efficiency of singlet oxygen formation are quantitatively reproduced by a model that assumes the competition between a non-charge transfer (nCT) and a CT deactivation channel. The balance between CT and nCT deactivation channels, which is described by the relative contribution p(CT) of CT induced deactivation, is discussed. The kinetic model is found to be successfully applied in the case of quenching of the excited triplet states of coordination compounds by oxygen in acetonitrile, as was proposed for the quenching of pi-pi* triplet states by oxygen. 相似文献
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The zeros in the complex z plane of the Whittaker function Wc/z,µ(z),closely related to spherical waves in the quantum-mechanicalCoulomb problem, are investigated for varying real values ofthe parameters c and µ 相似文献
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Ewa Sikorska Jose R. Herance Jose L. Bourdelande Igor V. Khmelinskii Sin L. Williams David R. Worrall Grayna Nowacka Anna Komasa Marek Sikorski 《Journal of photochemistry and photobiology. A, Chemistry》2005,170(3):267-272
Electronic structure and singlet–singlet and triplet–triplet absorption spectra of 3-ethyl-lumiflavin were calculated using time-dependent density functional theory (TD-DFT) methods. The measured lower-energy transitions are well reproduced in calculations, which are limited by the neglect of the solvent interactions. All the observable singlet–singlet and triplet–triplet transitions have π–π* character. Singlet oxygen production by the studied compound demonstrated that, similar to other lumiflavins, it is an efficient singlet oxygen sensitizer (Δ = 0.55). Radiationless deactivation of the S1 state in solutions was shown to result in the T1 state formation. 相似文献
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Marí a S. Galletero Hermenegildo Garcí a Jos L. Bourdelande 《Chemical physics letters》2003,370(5-6):829-833
The triplet excited state of C60 (λmax=780 nm) lives minutes and can be monitored by conventional spectrophotometers when this fullerene is incorporated inside LiY, as opposed to C60@HY and C60@MCM-41 wherein C60 triplet lives in the submillisecond time scale. C60 adsorbed in LiY or MCM-41 efficiently generates 1O2 that was detected by its characteristic NIR emission (λem=1270 nm). 相似文献
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Laura Amorín‐Ferré Dr. Félix Busqué Dr. José Luis Bourdelande Dr. Daniel Ruiz‐Molina Dr. Jordi Hernando Dr. Fernando Novio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17508-17516
The interplay of guest encapsulation and release mechanisms in nanoscale metal–organic vehicles and its effect on the drug‐delivery kinetics of these materials were investigated through a new multidisciplinary approach. Two rationally‐designed molecular guests were synthesized, which consist of a red‐fluorescent benzophenoxazine dye covalently tethered to a coordinating catechol group and a protected, non‐coordinating catechol moiety. This allowed loading of the guests into compositionally and structurally equivalent coordination polymer particles through distinct encapsulation mechanisms: coordination and mechanical entrapment. The two types of particles delivered their fluorescent cargo with remarkably different kinetic profiles, which could be satisfactorily modeled considering degradation‐ and diffusion‐controlled release processes. This demonstrates that careful selection of the method of guest incorporation into coordination polymer nanoparticles allows selective tuning of the rate of drug delivery from these materials and, therefore, of the time window of action of the encapsulated therapeutic agents. 相似文献
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Mark T McAuley Rose Anne Kenny Thomas BL Kirkwood Darren J Wilkinson Janette JL Jones Veronica M Miller 《BMC neuroscience》2009,10(1):26