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971.
Synthesis of 2,6-diaryl-1,2-dihydropyridines through a 6π-electrocyclization of N-sulfonylazatrienes
The development of an efficient synthetic method toward substituted 1,2-dihydropyridines from cinnamylideneacetophenones is reported. The key intermediates N-sulfonylazatrienes were synthesized through a TiCl4-mediated direct condensation of primary sulfonamides with the substituted (E,E)-cinnamylideneacetophenones. The 6π-electrocyclization of these intermediates, catalyzed by a Lewis acid, selectively afforded the desired products in good yields. 相似文献
972.
Silvia García‐Rubín Carlos Gonzlez‐Rodríguez Cristina García‐Yebra Jesús A. Varela Miguel A. Esteruelas Carlos Sa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(7):1872-1875
A new synthetic route to dihydrobiphenylenes has been developed. The process involves a mild RuII‐catalyzed [2+2+2] dimerization of ortho‐alkenylarylacetylenes or its more versatile variant, the Ru‐catalyzed [2+2+2] cycloaddition of ortho‐ethynylstyrenes with alkynes. Mechanistic aspects of this [2+2+2] cycloaddition are discussed. 相似文献
973.
Cristina Ileana Covaliu Daniela Berger Cristian Matei Lucian Diamandescu Eugeniu Vasile Camelia Cristea Valentin Ionita Horia Iovu 《Journal of nanoparticle research》2011,13(11):6169-6180
This study reports a two-steps route for obtaining magnetic nanoparticles–polysaccharide hybrid materials consisting of Fe3O4, NiFe2O4 and CuFe2O4 nanoparticles synthesis by coprecipitation method in the presence of a soft template followed by coating of ferrite nanoparticles of 8–10-nm size range with polysaccharide type polymers—sodium alginate or chitosan. Magnetic oxide nanoparticles and the corresponding hybrid materials were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy, atomic absorption spectroscopy (AAS), FTIR spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and specific surface area measurements. The vibrating sample magnetometry confirms the superparamagnetic properties of the synthesized ferrites and hybrids. Using this route, the percent of magnetic nanoparticles retained in chitosan-based hybrid materials is nearly double in comparison with that of sodium alginate–based materials. The biological activity tests on Escherichia coli ATCC 25922, Pseudomonas aeroginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Candida scotti microorganisms show the non-toxic properties of prepared hybrid materials. 相似文献
974.
Beninca Cleoci Bisinella Radla Zabian Bassetto Bet Camila Delinski de Oliveira Cristina Soltovski Barboza Raíssa Arantes Colman Tiago André Denck Demiate Ivo Mottin Schnitzler Egon 《Journal of Thermal Analysis and Calorimetry》2020,140(2):743-753
Journal of Thermal Analysis and Calorimetry - The Araucaria angustifolia seed, named pinhão, has a high content of carbohydrates, and it is considered an unconventional starch source. Its... 相似文献
975.
Khouloud Dammak Marina Porchia Michele De Franco Mirella Zancato Houcine Naïli Valentina Gandin Cristina Marzano 《Molecules (Basel, Switzerland)》2020,25(22)
A series of neutral mixed-ligand [HB(pz)3]Ag(PR3) silver(I) complexes (PR3 = tertiary phosphine, [HB(pz)3]− = tris(pyrazolyl)borate anion), and the corresponding homoleptic [Ag(PR3)4]BF4 compounds have been synthesized and fully characterized. Silver compounds were screened for their antiproliferative activities against a wide panel of human cancer cells derived from solid tumors and endowed with different platinum drug sensitivity. Mixed-ligand complexes were generally more effective than the corresponding homoleptic derivatives, but the most active compounds were [HB(pz)3]Ag(PPh3) (5) and [Ag(PPh3)4]BF4 (10), both comprising the lipophilic PPh3 phosphine ligand. Detailed mechanistic studies revealed that both homoleptic and heteroleptic silver complexes strongly and selectively inhibit the selenoenzyme thioredoxin reductase both as isolated enzyme and in human ovarian cancer cells (half inhibition concentration values in the nanomolar range) causing the disruption of cellular thiol-redox homeostasis, and leading to apoptotic cell death. Moreover, for heteroleptic Ag(I) derivatives, an additional ability to damage nuclear DNA has been detected. These results confirm the importance of the type of silver ion coordinating ligands in affecting the biological behavior of the overall corresponding silver complexes, besides in terms of hydrophilic–lipophilic balance, also in terms of biological mechanism of action, such as interaction with DNA and/or thioredoxin reductase. 相似文献
976.
Cristina Rodríguez‐Seco Maria Mndez Cristina Roldn‐Carmona Ravi Pudi Mohammad Khaja Nazeeruddin Emilio Jose Palomares 《Angewandte Chemie (International ed. in English)》2020,59(13):5303-5307
Three hole transport materials (HTMs) based on a substituted triphenylamine moiety have been synthesized and successfully employed in triple‐cation mixed‐halide PSCs, reaching efficiencies of 19.4 %. The efficiencies, comparable to those obtained using spiro‐OMeTAD, point them out as promising candidates for easily attainable and cost‐effective alternatives for PSCs, given their facile synthesis from commercially available materials. Interestingly, although all these HTMs show similar chemical and physical properties, they provide different carrier recombination kinetics. Our results demonstrate that is feasible through the molecular design of the HTM to minimize carrier losses and, thus, increase the solar cell efficiencies. 相似文献
977.
Study of the Complexation of Pb(II) with meso‐2,3‐ Dimercaptosuccinic Acid (DMSA) and 2,3‐Dimercapto‐1‐propanesulfonic acid (DMPS) Using a Bismuth‐Bulk Rotating Disk Electrode 下载免费PDF全文
María de la Gala Morales Cristina Ariño José Manuel Díaz‐Cruz Miquel Esteban 《Electroanalysis》2014,26(9):1912-1919
For the first time, the suitability of bismuth bulk rotating disk electrode (BiB‐RDE) for the study of metal complexation has been tested. Cyclic (CV) and differential pulse (DPV) voltammetry have been used to study the complexation of Pb(II) with two of the most effective chelating agents for the treatment of Pb(II) poisoning (meso‐2,3‐dimercaptosuccinic acid, DMSA, and 2,3‐dimercapto‐1‐propanesulfonic acid, DMPS). Multivariate curve resolution has been applied to voltammetric data to obtain the stoichiometries and stability constants of the complexes formed. In both systems, the ML2 complex was predominant, with log β2 values of 10.13 and 8.80 for DMSA‐Pb(II) and DMPS‐Pb(II), respectively. 相似文献
978.
Pressure‐sensitive adhesives (PSA) are used to manufacture labels that are applied directly on the food. These adhesives could contain not only intentionally added compounds (IAS) to the adhesive formula but also non‐intentionally added substances (NIAS), due to the impurities from the raw materials used, decomposition of the initial components or from chemical interactions between them. These compounds could migrate to the food and contaminate it. In this study, gas chromatography coupled with mass spectrometry (GC‐MS/Q) and atmospheric pressure gas chromatography coupled to a quadrupole hyphenated to a time of flight mass spectrometer (APGC‐MS/Q‐TOF) have been used for identification of unknown compounds and NIAS coming from a PSA. Seven compounds were identified by GC‐MS/Q, and other eight compounds remained initially unknown. The structure of these eight new compounds was elucidated by working with the spectra obtained by APGC‐MS/Q‐TOF. Finally, two different migration studies were carried out. The first one with Tenax as solid food simulant in contact with the paper label containing the adhesive and the second one with isooctane filled in a natural pork intestine where the label containing the adhesive was applied on the external side. The results are shown and discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
979.
Hydride Migration from a Triangular Face to a Tetrahedral Cavity in Tetranuclear Iron Carbonyl Clusters upon Coordination of [AuPPh3]+ Fragments 下载免费PDF全文
Dr. Marco Bortoluzzi Dr. Iacopo Ciabatti Dr. Cristina Femoni Dr. Mohammad Hayatifar Prof. Maria Carmela Iapalucci Prof. Giuliano Longoni Prof. Stefano Zacchini 《Angewandte Chemie (International ed. in English)》2014,53(28):7233-7237
Metal hydrides are of fundamental importance in chemistry, both as solid‐state materials and molecular compounds. The first low‐valent molecular metal cluster containing an interstitial four‐coordinate hydride in a tetrahedral site is decribed, which undergoes hydride migration from the surface to the tetrahedral cavity of the cluster upon coordination of a [AuPPh3]+ fragment. The [HFe4(CO)12(AuPPh3)2]? mono‐anion, which contains a surface μ3‐H, was obtained from the reaction of [HFe4(CO)12]3? with two equivalents of [Au(PPh3)Cl]. This is, in turn, transformed into the neutral [HFe4(CO)12(AuPPh3)3] upon addition of a third [AuPPh3]+ fragment, with concomitant migration of the unique hydride from the surface of the cluster to its tetrahedral cavity. All of these species have been fully characterized in solution by means of IR and multinuclear NMR spectroscopy, and in the solid state by single‐crystal X‐ray diffractometry. 相似文献
980.
Cavitand‐Grafted Silicon Microcantilevers as a Universal Probe for Illicit and Designer Drugs in Water 下载免费PDF全文
Dr. Elisa Biavardi Dr. Stefania Federici Dr. Cristina Tudisco Dr. Daniela Menozzi Dr. Chiara Massera Andrea Sottini Prof. Guglielmo G. Condorelli Dr. Paolo Bergese Prof. Enrico Dalcanale 《Angewandte Chemie (International ed. in English)》2014,53(35):9183-9188
The direct, clean, and unbiased transduction of molecular recognition into a readable and reproducible response is the biggest challenge associated to the use of synthetic receptors in sensing. All possible solutions demand the mastering of molecular recognition at the solid–liquid interface as prerequisite. The socially relevant issue of screening amine‐based illicit and designer drugs is addressed by nanomechanical recognition at the silicon–water interface. The methylamino moieties of different drugs are all first recognized by a single cavitand receptor through a synergistic set of weak interactions. The peculiar recognition ability of the cavitand is then transferred with high fidelity and robustness on silicon microcantilevers and harnessed to realize a nanomechanical device for label‐free detection of these drugs in water. 相似文献