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281.
Preparation,Characterization and Electrochemical Behavior of Pd‐Au Alloy Incorporated into Zeolites/Graphite Electrodes
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The present article reports the preparation of Pd‐Au alloy incorporated into NaY zeolites layer via simple immersion technique. Pd‐Au particles were incorporated into zeolites cages via Co‐impregnation or alternate impregnation of metal ions. Cyclic voltammetry was used to evaluate the state of the modified electrodes in alkaline media. Surface morphology as well as elemental composition of the modified layer were examined using Scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX). 相似文献
282.
A. A. Aleksandrov E. V. Illenzeer M. M. El’chaninov 《Russian Journal of General Chemistry》2014,84(4):682-685
Condensation of 1-amino-2-hydroxynaphthalene with thenoyl chloride in 1-methyl-2-pyrrolidinone medium afforded 2-(2-thienyl)naphtho[1,2-d]oxazole. The latter was brought into electrophilic substitution reactions like nitration, bromination, sulfonation, formylation, and acylation. The reactions proceeded via electrophilic attack at the 5-position of the thiophene ring, but the nitration and bromination occurred involving both the thiophene and naphthalene fragments. 相似文献
283.
Joshua Buse Randy W. Purves Ronald E. Verrall Ildiko Badea Haixia Zhang Christopher C. Mulligan Kerry M. Peru Jonathan Bailey John V. Headley Anas El‐Aneed 《Journal of mass spectrometry : JMS》2014,49(11):1171-1180
The safe use of lipid‐based drug delivery agents requires fast and sensitive qualitative and quantitative assessment of their cellular interactions. Many mass spectrometry (MS) based analytical platforms can achieve such task with varying capabilities. Therefore, four novel high‐throughput MS‐based quantitative methods were evaluated for the analysis of a small organic gene delivery agent: N,N‐bis(dimethylhexadecyl)‐1,3‐propane‐diammonium dibromide (G16‐3). Analysis utilized MS instruments that detect analytes using low‐resolution tandem MS (MS/MS) analysis (i.e. QTRAP or linear ion trap in this work) or high‐resolution MS analysis (i.e. time of flight (ToF) or Orbitrap). Our results indicate that the validated fast chromatography (FC)‐QTRAP‐MS/MS, FC‐ LTQ‐Orbitrap‐MS, desorption electrospray ionization‐collision‐induced dissociation (CID)‐MS/MS and matrix assisted laser desorption ionization‐ToF/ToF‐MS MS methods were superior in the area of method development and sample analysis time to a previously developed liquid chromatography (LC)‐CID‐MS/MS. To our knowledge, this is the first evaluation of the abilities of five MS‐based quantitative methods that target a single pharmaceutical analyte. Our findings indicate that, in comparison to conventional LC‐CID‐MS/MS, the new MS‐based methods resulted in a (1) substantial reduction in the analysis time, (2) reduction in the time required for method development and (3) production of either superior or comparable quantitative data. The four new high‐throughput MS methods, therefore, were faster, more efficient and less expensive than a conventional LC‐CID‐MS/MS for the quantification of the G16‐3 analyte within tissue culture. When applied to cellular lysate, no significant change in the concentration of G16‐3 gemini surfactant within PAM212 cells was observed between 5 and 53 h, suggesting the absence of any metabolism/excretion from PAM212 cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
284.
Mild Bioconjugation Through the Oxidative Coupling of ortho‐Aminophenols and Anilines with Ferricyanide
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Allie C. Obermeyer John B. Jarman Chawita Netirojjanakul Kareem El Muslemany Prof. Dr. Matthew B. Francis 《Angewandte Chemie (International ed. in English)》2014,53(4):1057-1061
Using a small‐molecule‐based screen, ferricyanide was identified as a mild and efficient oxidant for the coupling of anilines and o‐aminophenols on protein substrates. This reaction is compatible with thiols and 1,2‐diols, allowing its use in the creation of complex bioconjugates for use in biotechnology and materials applications. 相似文献
285.
Dr. Alexander Sachse Caroline Wuttke Dr. Elízio Lissner Dr. Michèle Oberson de Souza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):14996-14999
Hierarchically porous ZSM‐5 was achieved by using a simple bottom‐up strategy combining zeolite seeds with imidazolium‐based ionic liquids. The bimodal ZSM‐5 with hexagonal arranged mesopores (3 nm) shows important activity in the acid catalysis of bulky compounds relative to conventional ZSM‐5. 相似文献
286.
Dr. Romain Ramozzi Dr. Nicolas Chéron Dr. Laurent El Kaïm Dr. Laurence Grimaud Dr. Paul Fleurat‐Lessard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9094-9099
Following our previous mechanistic studies of multicomponent Ugi‐type reactions, theoretical calculations have been performed to predict the efficiency of new substrates in Ugi–Smiles couplings. First, as predicted, 2,4,6‐trichlorophenol experimentally gave the corresponding aryl‐imidate. Theoretical predictions of nitrosophenols as good acidic partners were then successfully confirmed by experiments. In the latter case, the reaction offers a new access to benzimidazoles. 相似文献
287.
Tandem CH Activation/Arylation Catalyzed by Low‐Valent Iron Complexes with Bisiminopyridine Ligands
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Elise Salanouve Ghania Bouzemame Dr. Sébastien Blanchard Dr. Etienne Derat Dr. Marine Desage‐El Murr Prof. Louis Fensterbank 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4754-4761
Tandem C?H activation/arylation between unactivated arenes and aryl halides catalyzed by iron complexes that bear redox‐active non‐innocent bisiminopyridine ligands is reported. Similar reactions catalyzed by first‐row transition metals have been shown to involve substrate‐based aryl radicals, whereas our catalytic system likely involves ligand‐centered radicals. Preliminary mechanistic investigations based on spectroscopic and reactivity studies, in conjunction with DFT calculations, led us to propose that the reaction could proceed through an inner‐sphere C?H activation pathway, which is rarely observed in the case of iron complexes. This bielectronic noble‐metal‐like behavior could be sustained by the redox‐active non‐innocent bisiminopyridine ligands. 相似文献
288.
Haq Nawaz Paulo A. R. Pires Thaís A. Bioni Elizabeth P. G. Arêas Omar A. El Seoud 《Cellulose (London, England)》2014,21(3):1193-1204
Rate constants for the acetylation of microcrystalline cellulose (MCC), by ethanoic anhydride in the presence of increasing concentrations of the ionic liquid (IL), 1-allyl-3-methylimidazolium chloride in dipolar aprotic solvents (DAS), N,N-dimethylacetamide (DMAC), and acetonitrile (MeCN), have been calculated from conductivity data. The third order rate constants showed a linear dependence on [IL]. We explain this result by assuming that the reacting cellulose is hydrogen-bonded to the IL. This is corroborated by kinetic data of the acetylation of cyclohexylmethanol, FTIR of the latter compound and of cellobiose in mixtures of IL/DAS, and conductivity of the binary solvent mixtures in absence, and presence of MCC. Cellulose acetylation is faster in IL/DMAC than in IL/MeCN; this difference is explained based on solvatochromic data (empirical polarity and basicity) and molecular dynamics simulations. Results of the latter indicate hydrogen-bond formation between the hydroxyl groups of the anhydroglucose unit of MCC, (Cl?) of the IL, and the dipole of the DMAC. Under identical experimental conditions, acetylation in IL/DMAC is faster than that in LiCl/DMAC (2.7–8 times), due to differences in the enthalpies and entropies of activation. 相似文献
289.
Brønsted Acid Catalyzed,Conjugate Addition of β‐Dicarbonyls to In Situ Generated ortho‐Quinone Methides—Enantioselective Synthesis of 4‐Aryl‐4H‐Chromenes
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M. Sc. Osama El‐Sepelgy M. Sc. Stefan Haseloff Dr. Santosh Kumar Alamsetti Prof. Dr. Christoph Schneider 《Angewandte Chemie (International ed. in English)》2014,53(30):7923-7927
We describe herein a catalytic, enantioselective process for the synthesis of 4H‐chromenes which are important structural elements of many natural products and biologically active compounds. A sequence comprising a conjugate addition of β‐diketones to in situ generated ortho‐quinone methides followed by a cyclodehydration reaction furnished 4‐aryl‐4H‐chromenes in generally excellent yields and high optical purity. A BINOL‐based chiral phosphoric acid was employed as a Brønsted acid catalyst which converted ortho‐hydroxy benzhydryl alcohols into hydrogen‐bonded ortho‐quinone methides and effected the carbon–carbon bond‐forming event with high enantioselectivity. 相似文献
290.
Interaction of Fluorescently Labeled Triethyleneglycol and Peptide Derivatives with β‐Cyclodextrin
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Dr. Mohamed‐Anis Alouini Dr. El‐Farouck Moustoifa Dr. Sandra Rubio‐Albenque Dr. Thomas Berthelot Dr. Suzanne Fery‐Forgues Prof. Gérard Déléris 《Chemphyschem》2014,15(3):444-457
A triethyleneglycol (TEG) chain, a linear peptide, and a cyclic peptide labeled with 7‐methoxycoumarin‐3‐carboxylic acid (MC) and 7‐diethylaminocoumarin‐3‐carboxylic acid (DAC) were used to thoroughly study Förster resonance energy transfer (FRET) in inclusion complexes. 1H NMR evidence was given for the formation of a 1:1 inclusion complex between β‐cyclodextrin (β‐CD) and the fluorophore moieties of model compounds. The binding constant was 20 times higher for DAC than for MC derivatives. Molecular modeling provided additional information. The UV/Vis absorption and fluorescence properties were studied and the energy transfer process was quantified. Fluorescence quenching was particularly strong for the peptide derivatives. The presence of β‐CDs reduced the FRET efficiency slightly. Dye‐labeled peptide derivatives can thus be used to form inclusion complexes with β‐CDs and retain most of their FRET properties. This paves the way for their subsequent use in analytical devices that are designed to measure the activity of matrix metalloproteinases. 相似文献