Search results for " Local"
showing 10 items of 2101 documents
Photoaffinity cross-linking of F1ATPase from the thermophilic bacterium PS3 by 3′-arylazido-β-alanyl-2-azido ATP
1989
AbstractThe photoactivatable bifunctional 3′-arylazido-β-alanyl-2-azido ATP (2,3′-DiN3ATP) has been applied to study the localization of the nucleotide-binding sites of coupling factor 1 (F1ATPase, TF1) from the thermophilic bacterium PS3 by photoaffinity cross-linking. UV irradiation of TF1 in the presence of 2,3′-DiN3ATP results in the nucleotide-dependent formation of various higher molecular mass cross-links formed by two, three or even four α- and/or β-subunits. The differences observed upon photoaffinity cross-linking by the bifunctional 2-azido ATP or 8-azido ATP analog are discussed. They are probably due to the varied maximal distance between both azido groups, or to the different …
Spectroscopic and structural characterization of pure and FeCl3-containing tri-n-butyl phosphate
2014
The spectroscopic properties and liquid structure of pure tri-n-butyl phosphate (TBP) and FeCl3/TBP solutions have been investigated by Uv–Vis and Raman spectroscopies, X-ray diffraction and conductometry. Uv–Vis and Raman spectra, supported by conductometric measurements, consistently indicate that the solubilized salt is present mostly as TBP n [FeCl3 − n ] n+ and FeCl4 − complex ions due to specific interaction with the TBP phosphate group. Thanks to this interaction, a high amount of salt (up to 13 % w/w) can be dissolved despite the relatively low dielectric constant of TBP. The X-ray diffractogram of pure TBP has been interpreted in terms of three main contributions which can be attri…
Studies of Nature of Uncommon Bifurcated I–I···(I–M) Metal-Involving Noncovalent Interaction in Palladium(II) and Platinum(II) Isocyanide Cocrystals
2021
Two isostructural trans-[MI2(CNXyl)2]·I2 (M = Pd or Pt; CNXyl = 2,6-dimethylphenyl isocyanide) metallopolymeric cocrystals containing uncommon bifurcated iodine···(metal–iodide) contact were obtained. In addition to classical halogen bonding, single-crystal X-ray diffraction analysis revealed a rare type of metal-involved stabilizing contact in both cocrystals. The nature of the noncovalent contact was studied computationally (via DFT, electrostatic surface potential, electron localization function, quantum theory of atoms in molecules, and noncovalent interactions plot methods). Studies confirmed that the I···I halogen bond is the strongest noncovalent interaction in the systems, followed …
Understanding the kinetic solvent effects on the 1,3-dipolar cycloaddition of benzonitrile N-oxide: a DFT study
2011
JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, ISSN : 0894-3230, DOI : 10.1002/poc.1858, Issue : 7, Volume : 24, pp. 611 – 618, JUILLET 2011.
An Understanding of the Electrophilic/Nucleophilic Behavior of Electro-Deficient 2,3-Disubstituted 1,3-Butadienes in Polar Diels−Alder Reactions. A D…
2008
The electrophilic/nucleophilic behavior of dimethyl 2,3-dimethylenesuccinate 1, an electron-deficient 2,3-disubstituted 1,3-butadiene, in polar Diels-Alder reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The electronic nature of bonding of the transition structures involved in the cycloaddition reactions of the diene 1 toward the nucleophilically activated dienophile 6 and the strong electrophilically activated dienophile 7 has been carefully examined within the natural bond orbital (NBO) and the topological analysis of the electron localization function (ELF) frameworks. Additionally, a study of the global electrophilicity pattern of the reagents at the …
Better understanding of the ring-cleavage process of cyanocyclopropyl anionic derivatives. A theoretical study based on the electron localization fun…
2005
[reaction: see text] Theoretical calculations at the B3LYP/6-31+G(d), MP2/6-31+G(d), and G3(MP2) levels have been carried out to understand the alternative reaction pathways (the cyclopropyl ring cleavage (RC) and the retrocycloaddition reaction (rCA)) of a constrained tricyanocyclopropyl anionic derivative. The more energetically favorable path is found to be the RC process, a formally "forbidden" rearrangement (Leiviers, M.; Tam, I.; Groves, K.; Leung, D.; Xie, Y.; Breslow, R. Org. Lett. 2003, 5, 19, 3407) yielding an allylic anion system via a concerted transition structure, in agreement with experimental outcomes. rCA is more energetically favorable along a two-stage mechanism, via an i…
Understanding the Influence of the Trifluoromethyl Group on the Selectivities of the [3+2] Cycloadditions of Thiocarbonyl S ‐methanides with α,β‐Unsa…
2020
Closer Investigation of the Kinetics and Mechanism of Spirovinylcyclopropyl Oxindole Reaction with 3Σ–g-O2 by Topological Approaches and Unraveling t…
2021
In this investigation at the MN15L/Def2-TZVP level of theory, we present computational evidence indicating that the reaction of 3Σ-g-O2 with spirovinylcyclopropyl oxindole (2) leads to a product called spiro-1,2-dioxolane (2) in its singlet state; this reaction occurs via a stepwise mechanism and its rate-determining step is catalyzed by iodine radicals, which promotes opening of the three-membered ring under dark conditions. The conversion of 2 to 1-benzylindoline-2,3-dione (3) and 2-vinyloxirane (4) takes place via a concerted and slightly asynchronous reaction. Both electron localization function and AIM topological analysis reveal that the step associated with the attack of the 3Σ-g-O2 …
Ciberperiodismo en el ámbito local: el caso del diario Levante-EMV
2008
Uno de los siete estudios de caso que, con el fin de preparar la comparación entre medios brasileños y españoles, se ha llevado a cabo desde el grupo español se refiere al diario Levante – El Mercantil Valenciano, que opera en las tres provincias (Valencia, Castellón y Alicante) de la Comunidad Valenciana, aunque principalmente en la primera de ellas. A continuación realizaremos un esbozo de los orígenes del periódico (tanto la versión digital como la impresa) y sus principales características, que posteriormennte quedarán explicitadas con mayor claridad merced a la exposición de los resultados del análisis