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881.
Samira Zeroual Nathalie Bouet Fabien Tuyèras Cyril Peltier Nadia Ouddai Philippe Ochsenbein Carlo Adamo Philippe P. Lainé Ilaria Ciofini 《Theoretical chemistry accounts》2012,131(2):1107-10
With the aim of designing new inorganic photosensitizers for photovoltaic applications, the structural and electronic properties
of two Ru(II) complexes containing terpyridine-based ligands derived from expanded pyridiniums both branched—polyphenyl—and
fused—polycyclic—were investigated by the means of density functional theory (DFT) and time-dependent DFT (TD-DFT). In particular,
the structure and electronic absorption of the fused architectures—including the isolated ligand and its complex—were compared
with those of their respective branched precursors with the aim to account for the their enhanced electronic features in the
visible spectral region. The theoretical insights gained into the “large-surface” ligand and its associated complex open the
route for a joint experimental and theoretical design of new inorganic photosensitizers based on fused expanded pyridiniums. 相似文献
882.
Jolly PI Fleary-Roberts N O'Sullivan S Doni E Zhou S Murphy JA 《Organic & biomolecular chemistry》2012,10(30):5807-5810
The bis-pyridinylidene 13 converts aliphatic and aryl triflate esters to the corresponding alcohols and phenols respectively, using DMF as solvent, generally in excellent yields. While the deprotection of aryl triflates has been seen with other reagents and by more than one mechanism, the deprotection of alkyl triflates is a new reaction. Studies with (18)O labelled DMF indicate that the C-O bond stays intact and hence it is the S-O bond that cleaves, underlining that the cleavage results from the extraordinary electron donor capability of 13. Trifluoromethanesulfonamides are converted to the parent amines in like manner, representing the first cleavage of such substrates by a ground-state organic reducing reagent. 相似文献
883.
Balucani N 《Chemical Society reviews》2012,41(16):5473-5483
Gas-phase reactions involving atomic nitrogen in the ground (4)S and first excited (2)D electronic states with simple hydrocarbons or hydrocarbon radicals lead to the formation of prebiotic N-containing organic molecules. These reactions are now active in the upper atmosphere of Titan (a massive moon of Saturn) and might have played an important role in nitrogen fixation in the primitive upper terrestrial atmosphere, assuming that it is similar to the present atmosphere of Titan. The products of these reactions (nitriles, imines and radicals) are the precursors of larger N-containing molecules, which form the dense haze aerosols that completely cover the moon of Saturn. If anything similar to Titan's haze has ever existed on our planet, it is reasonable to imagine that, once deposited on the surface of the oceans, further chemical evolution might have transformed these molecules into aminoacids and nucleobases, the molecular building blocks of living entities. The experimental techniques necessary to investigate these reactions in detail are presented and the main results reviewed. 相似文献
884.
Pouech C Tournier M Quignot N Kiss A Wiest L Lafay F Flament-Waton MM Lemazurier E Cren-Olivé C 《Analytical and bioanalytical chemistry》2012,402(9):2777-2788
Endocrine disrupting compounds (EDCs) are suspected to be responsible for many disorders of the human reproductive system.
To establish a causality relationship between exposure to endocrine disruptors and disease, experiments on animals must be
performed with improved or new analytical tools. Therefore, a simple, rapid, and effective multi-residue method was developed
for the determination of four steroid hormones (i.e., testosterone, androstenedione, estrone, and estradiol), glucuronide
and sulfate conjugates of estrone and estradiol and four endocrine disruptors in rat testis (i.e., bisphenol A, atrazine,
and active metabolites of methoxychlor and vinclozolin). The sample preparation procedure was based on the Quick, Easy, Cheap,
Effective, Rugged, and Safe (QuEChERS) approach. An analytical method was then developed to quantify these compounds at ultra-trace
levels by liquid chromatography coupled to tandem mass spectrometry. The QuEChERS extraction was optimized with regard to
the acetonitrile/water ratio used in the extraction step, the choice of the cleanup method and the acetonitrile/hexane ratio
used in the cleanup step. The optimized extraction method exhibited recoveries between 89% and 108% for all tested compounds
except the conjugates (31% to 58%). The detection limits of all compounds were below 20 ng g−1 of wet weight of testis. The method was subsequently applied to determine the levels of hormones and EDCs in seven rat testis
samples. 相似文献
885.
Ran Y. Suckeveriene Ron Rahman Irina Shtein Nadia Kharlamova Moshe Narkis 《先进技术聚合物》2012,23(12):1536-1542
This paper summarizes a study on emulsifier‐free ultrasonically assisted in situ dynamic interfacial emulsion copolymerization process of acrylamide and styrene. The resulting emulsions are stable and uniform for several months. Thermogravimetric analysis (TGA) curves and reaction conversion measurements have provided an important knowledge regarding the emulsifier‐free polymerization method. Solvent extractions (water, methanol, and xylene) have shown that the polymerization product is essentially a styrene–acrylamide copolymer. The copolymer produced is a block copolymer, PS‐b‐PAM, where each block contains small amounts of the other comonomer. The produced emulsions are film forming at room temperature in spite of the very high block Tgs, owing to a unique water plasticization effect of the polyacrylamide blocks. Some films prepared from the PS‐b‐PAM have resulted in clear and transparent films. The presented interfacial dynamic polymerization process is fast, reaching 81% conversion within 2 hr of sonication at 4°C (low temperature owing to molecular weight and kinetic considerations), and produces very stable PS‐b‐PAM emulsions. TGA was extensively used as an analytical tool for determination of the reaction parameters and composition of the acrylamide–styrene copolymers. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
886.
César V Tourneux JC Vujkovic N Brousses R Lugan N Lavigne G 《Chemical communications (Cambridge, England)》2012,48(17):2349-2351
An elusive free 4-(isopropylamino)imidazol-2-ylidene is engaged in a tautomeric equilibrium with its mesoionic tautomer, 4-(isopropylamido)imidazolium, which displays the typical reactivity of a cyclic diaminocarbene; once coordinated to a Rh(I) centre, it undergoes a smooth 4e(-) oxidation of its backbone to yield an amido-amidino-carbene, a weak electron donor viable only in its complexed form. 相似文献
887.
888.
Mutation scanning-based analysis of Theileria orientalis populations in cattle following an outbreak
Bovine theileriosis is a tick-borne disease caused by one or more hemoprotozoan parasites of the genus Theileria. In the past, Theileria infection in cattle in Australia was largely asymptomatic and recognized to be associated with Theileria buffeli. However, outbreaks of theileriosis have occurred in beef and dairy cattle in subtropical climatic regions (New South Wales) of Australia. There is also one published report of a recent theileriosis outbreak in a beef farm near Seymour in the southeastern state of Victoria. In order to gain an improved insight into the genetic composition of Theileria populations following this outbreak, we undertook herein an integrated PCR-coupled mutation scanning-sequencing-phylogenetic analysis of sequence variation in part of the major piroplasm surface protein (MPSP) gene within and among samples from cattle involved in the outbreak. Theileria DNA was detected in 89.4% of 94 cattle in the Seymour farm; the genetic analysis showed that the ikeda and chitose genotypes representing the Theileria orientalis complex were detected in 75 and 4.8% of 84 infected cattle, respectively, and that mixed populations of these two genotypes were found in 20.2% of infected cattle. Given unpublished reports of a significant increase in the number of outbreaks in Victoria, future investigations should focus sharply on elucidating the epidemiology of Theileria to subvert the economic impact on the cattle industry in this state. Although used here to explore genetic variation within the T. orientalis complex in Australia, a mutation scanning-based approach has broad applicability to other species of Theileria in other countries. 相似文献
889.
A series of 2-substituted-1H-benzimidazole derivatives were synthesized and evaluated for antimicrobial, antifungal and cytotoxic activities. The results showed that all tested compounds showed potent antimicrobial activity against some species of Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi) and fungi (Candida albicans) with minimum inhibitory concentrations (MICs) lower than 0.016 μg/mL. In contrast, all tested compounds were inactive against Staphylococcus aureus (Gram-positive bacterium). The final targets were also tested for their antitumor activity in vitro on cervical carcinoma (HeLa) cell line. Eight of the test compounds displayed more potent cytotoxic effect than doxorubicin at nanomolar concentrations. Compounds 2c and 3c exerted the strongest cytoyoxic effect with IC(50) 15 and 13 nM, respectively. 相似文献
890.
Nadia Belfguira Siwar Walha Ahlem Kabadou Abdelhamid Ben Salah Frédéric Hatert André Mathieu Fransolet 《Journal of chemical crystallography》2011,41(3):370-374