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排序方式: 共有319条查询结果,搜索用时 15 毫秒
1.
E. Peter Kündig Chantal Dupr Bernadette Bourdin Allan Cunningham Dominique Pons 《Helvetica chimica acta》1994,77(2):421-428
Two new C2 chiral bidentate phosphorous ligands have been prepared in enantiomerically pure form. The two phosphorous centers bear electron-withdrawing groups ((CF3)2CH? O, C6F5) and are linked by a trans-cyclopentane-1,2-diol-derived bridge. Photolysis of [Cr(η6-C6H6)(CO)3] in the presence of these two new ligands and of two previously reported bidentate phosphites, and fluorophosphinites (L) afforded [Cr(η6-C6H6)(CO)L] complexes. IR Spectral comparison of the complexes shows the new ligands to be intermediate in their bonding properties between alkyl phosphites and CO. 相似文献
2.
Christians Ferradini Jacques Foos Chantal Houee Jacques Pucheault 《Photochemistry and photobiology》1978,28(4-5):697-700
Abstract— In order to obtain a better understanding of the kinetics of the Haber-Weiss reaction
often proposed as a source of OH radicals, we have measured the decomposition rate of H2 O2 in aqueous solutions by y rays and for different pH values. This decomposition proceeds by a chain reaction involving the preceding one as the propagating step.
The rate constant found is to be
相似文献
often proposed as a source of OH radicals, we have measured the decomposition rate of H
The rate constant found is to be
相似文献
3.
Claverie JM Monchois V Audic S Poirot O Abergel C 《Combinatorial chemistry & high throughput screening》2002,5(7):511-522
We outline a joint academic/industrial (CNRS/AVENTIS) functional genomics project aiming at the discovery of new anti-bacterial gene targets. Starting from all publicly available bacterial genomes, a subset of the most evolutionary conserved protein-coding genes has been identified. We retained genes with clear homolog in E. coli and at least one gram-positive bacterium among B.subtilis, M. tuberculosis, L. lactis or S. pyogenes. This subset was further reduced to genes encoding non-membrane proteins of unknown or hypothetical functions. The 221 E. coli Open Reading Frames (ORFs) identified through this comprehensive bioinformatic analysis are now submitted to a systematic 3-D structure determination protocol including cloning, protein expression and purification, crystallisation and X-ray diffraction. Our strategy was designed to focus on promising wide-spectrum targets as well as original biochemical pathways. Bioinformatics is used throughout all phases of project, including the initial large-scale comparative genomics analyses, the purification/expression and crystallisation stages for the detection of helpful sequence-specific features (e.g. cofactor binding motifs, non-structured N- or C- term extremities, etc ), and finally for the interpretation of the structures in conjunction with multiple sequence alignments for the identification of key residues, interaction areas on molecular surfaces, and overall function predictions. 相似文献
4.
5.
Robin J. Marles James B. Hudson Elizabeth A. Graham Chantal Soucy-Breau Peter Morand R. Lilia Compadre Cesar M. Compadre G. H. Neil Towers J. Thor Arnason 《Photochemistry and photobiology》1992,56(4):479-487
The photoactivated antiviral and cytotoxic activities of the naturally occurring thiophene, alpha-terthienyl (1), and 15 synthetic analogues were evaluated against murine cytomegalovirus and Sindbis virus, and murine mastocytoma cells. After irradiation with near UV light, alpha-terthienyl and most of its analogues had significant toxicity, with minimum inhibitory concentrations in the range of 0.02-40 microM. In the absence of near UV irradiation, only one analogue had antiviral activity and five were cytotoxic. The most active analogues were those containing carboxylic acid, hydroxyl, or cyano substituents. Quantitative structure-activity relationship analysis of thiophene phototoxicity suggested that the rate of singlet oxygen production is the primary determinant of antiviral and cytotoxic activities. For phototoxicity against murine cytomegalovirus, a significant role for hydrophobicity was also demonstrated. Tricyclic thiophenes show significant potential for photochemotherapy of viral infections and cancer, and further evaluation in animal models is recommended. 相似文献
6.
Laser processing for bio-microfluidics applications (part I) 总被引:1,自引:0,他引:1
Khan Malek CG 《Analytical and bioanalytical chemistry》2006,385(8):1351-1361
This paper reviews applications of laser-based techniques to the fabrication of microfluidic devices for biochips and addresses
some of the challenges associated with the manufacture of these devices. Special emphasis is placed on the use of lasers for
the rapid prototyping and production of biochips in particular for applications in which silicon is not the preferred material
base. Part I of this review addresses applications and devices using UV lasers for laser ablation and surface treatment of
microchannels, in particular in polymers. 相似文献
7.
The trans-cis isomerization of the styrylpyridine carbon-carbon double bond induced by visible light irradiation in fac-[Re(CO)(3)(bpy)(stpy)](+) (bpy = 2,2'-bipyridine; stpy = t-4-styrylpyridine) has been investigated by means of quantum-chemical methods. The structures of the various cis and trans conformers of [Re(CO)(3)(bpy)(stpy)](+) have been optimized at the density functional theory (DFT) level. Three rotational conformers for the most stable trans isomer lie within 2.3 kJ mol(-1) each other. The energy difference between the cis and trans isomers is 27.0 kJ mol(-1). The electronic spectroscopy of the most stable conformers has been investigated by time-dependent DFT (TD-DFT) and complete active space self-consistent field/CAS second order perturbation theory (CASSCF/CASPT2) calculations. The lowest absorption bands are dominated by metal-to-ligand charge-transfer (MLCT, d(Re)-->pi*(bpy)) transitions calculated at about 25,000 cm(-1) and by a strong intraligand (1)IL (pi(stpy)-->pi*(stpy)) transition in the near UV region. On the basis of CASSCF potential energy curves (PECs) calculated as a function of the torsion angle of the C=C bond of the styrylpyridine ligand, it is shown that the role of the low-lying MLCT states is important in the photoisomerization mechanism. In contrast to the free organic ligand, in which the singlet mechanism is operational via the (1)IL (S(1)) and electronic ground (S(0)) states, coordination to the rhenium steers the isomerization to the triplet PEC corresponding to the (3)IL state. From the (3)IL(t) (t = trans) the system evolves to the perpendicular intermediate (3)IL(p) (p = perpendicular) following a 90 degrees rotation around the styrylpyridine C=C bond. The metal center acts as a photosensitizer because of the presence of photoactive MLCT states under visible irradiation. The position of the crossing between the (3)IL and electronic ground state PEC determines the quantum yield of the isomerization process. 相似文献
8.
NIR‐to‐NIR Two‐Photon Scanning Laser Microscopy Imaging of Single Nanoparticles Doped by YbIII Complexes 下载免费PDF全文
Dr. Adrien Bourdolle Dr. Anthony D'Aléo Dr. Cécile Philippot Dr. Patrice L. Baldeck Dr. Yannick Guyot Dr. Fabien Dubois Dr. Alain Ibanez Dr. Chantal Andraud Dr. Sophie Brasselet Dr. Olivier Maury 《Chemphyschem》2016,17(1):128-135
The photophysical and nonlinear optical properties of water‐soluble chromophore‐functionalised tris‐dipicolinate complexes [LnL3]3? (Ln=Yb and Nd) are thoroughly studied, revealing that only the YbIII luminescence can be sensitized by a two‐photon excitation process. The stability of the complex in water is strongly enhanced by embedding in dispersible organosilicate nanoparticles (NPs). Finally, the spectroscopic properties of [NBu4]3[YbL3] are studied in solution and in the solid state. The high brightness of the NPs allows imaging them as single objects using a modified two‐photon microscopy setup in a NIR‐to‐NIR configuration. 相似文献
9.
Fernando P. Carvalho Jean-Pierre Villeneuve Chantal Cattini 《Trends in analytical chemistry : TRAC》1999,18(11):1005-664
A seaweed sample (Fucus sp.) was prepared, homogenised and distributed to laboratories worldwide as the IAEA-140 intercomparison material for the analysis of organochlorine compounds and petroleum hydrocarbons. A total of 80 laboratories from 51 countries reported results for this sample. The data sets reported by laboratories were evaluated statistically and the mean concentration values could be computed with 95% confidence limits for a large number of analytes. The accuracy of the analytical performance of each laboratory has been introduced by using Z-scores. The spread of results reported generally indicates that the accurate determination of many persistent organic pollutants, such as hexachlorobenzene, lindane, Aroclors or fluoranthene, is still difficult for many laboratories. The final results of this intercomparison exercise enable individual participants to assess their performance and, where necessary, to introduce appropriate modifications in their analytical procedures. Furthermore, as a series of statistical criteria was fulfilled for a number of compounds, the sample IAEA-140 can now be used as a reference material for quality control in the determination of chlorinated compounds and petroleum hydrocarbons in environmental samples. 相似文献
10.
Radka Baková Majed Chergui Chantal Daniel Antonín Vlček Stanislav Záliš 《Coordination chemistry reviews》2011,255(7-8):975-989
Spin–orbit coupling (SOC) is an essential factor in photophysics of heavy transition metal complexes. By enabling efficient population of the lowest triplet state and its strong emission, it gives rise to a very interesting photophysical behavior and underlies photonic applications such as organic light emitting diodes (OLED) or luminescent imaging agents. SOC affects excited-state characters, relaxation dynamics, radiative and nonradiative decay pathways, as well as lifetimes and reactivity. We present a new photophysical model based on mixed-spin states, illustrated by relativistic spin–orbit TDDFT and MS-CASPT2 calculations of [Re(imidazole)(CO)3(1,10-phenanthroline)]+. An excited-state scheme is constructed from spin–orbit (SO) states characterized by their energies, double-group symmetries, parentages in terms of contributing spin-free singlets and triplets, and oscillator strengths of corresponding transitions from the ground state. Some of the predictions of the relativistic SO model on the number and nature of the optically populated and intermediate excited states are qualitatively different from the spin-free model. The relativistic excited-state model accounts well for electronic absorption and emission spectra of ReI carbonyl diimines, as well as their complex photophysical behavior. Then, we discuss the SO aspects of photophysics of heavy metal complexes from a broader perspective. Qualitative SO models as well as previous relativistic excited-state calculations are briefly reviewed together with experimental manifestations of SOC in polypyridine and cyclometallated complexes of second- and third row d6 metals. It is shown that the relativistic SO model can provide a comprehensive and unifying photophysical picture. 相似文献