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Spectrophotometric methods were utilized for stability constant determinations of the Fe(III) interaction with glycinehydroxamic acid (GX) at I = 0.15 M NACl and T = 25°C. Program SQUAD II was used to assess the absorbance data in the wavelength range 300–520 nm. Four constants were determined for 1:1:1, 1:1:0, 2:1:1 or 3:1:3 and 2:1:0 complex species in the pH range 1.0–7.5. The kinetics of the interactions of Fe(III) with GX were also studied in the pH range 1.0–3.0 by the stopped flow method. The observed rate constant at a given pH was kobs = A + BTGX. The parameters A and B are functions of pH in the range 1.7–3.0 and only A is a function of pH in the range 1.0–1.7. The mechanism of complex formation was discussed in the light of the experimental results and the equilibrium study. It has been concluded that FeOH2+ is the reactive species in the complex formation of FeGXH3+ species while Fe(OH)2+ is the reactive species in the complex formation of FeGX2+ species. 相似文献
145.
The paper is devoted to studying the lower semicontinuity of vector-valued mappings. The main object under consideration is
the lower limit. We first introduce a new definition of an adequate concept of lower and upper level sets and establish some
of their topological and geometrical properties. A characterization of semicontinuity for vector-valued mappings is thereafter
presented. Then, we define a concept of vector lower limit, proving its lower semicontinuity, and furnishing in this way a
concept of lower semicontinuous regularization for mappings taking their values in a complete lattice. The results obtained
in the present work subsume the standard ones when the target space is finite dimensional. In particular, we recapture the
scalar case with a new flexible proof. In addition, extensions of usual operations of lower and upper limits for vector-valued
mappings are explored. The main result is finally applied to obtain a continuous D.C. decomposition of continuous D.C. mappings.
Dedicated to Alex Rubinov in honor of his 65th birthday 相似文献
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Alverson G Baker WF Ballocchi G Benson R Berg D Blusk S Bromberg C Brown D Carey D Chand T Chandlee C Choudhary BC Chung WH de Barbaro L DeSoi W Dlugosz W Dunlea J Easo S Engels E Faissler W Fanourakis G Ferbel T Garelick D Ginther G Glass G Glaubman M Gutierrez P Hartman K Huston J Johnstone C Kapoor V Kourbanis I Lanaro A Lirakis C Lobkowicz F Lukens P Mani S Maul A Mansour J Miller R Nelson CA Oh B Orris D Pothier E Prebys E Rajaram BM Roser R Ruddick K Shepard P Shivpuri RK Sinanidis A 《Physical review letters》1992,68(17):2584-2587
149.
L. Boubakri L. Mansour A. H. Harrath I. Özdemir 《Journal of Coordination Chemistry》2018,71(2):183-199
A novel series of N-heterocyclic carbene-phosphine palladium(II) complexes has been synthesized and fully characterized by IR, 1H NMR, 13C NMR, and 31P NMR spectroscopies, and elemental analysis. The new N-heterocyclic carbene (NHC)-phosphine palladium(II) complexes 3a–h have been easily prepared by the reaction of the corresponding PEPPSI (pyridine-enhanced precatalyst preparation stabilization and initiation) complexes 2a–h and triphenylphosphine in dichloromethane in high yields. These complexes were applied as catalyst precursors which efficiently catalyzed Sonogashira reactions between aryl bromides and phenylacetylene to afford the corresponding products in good yields. The bulky NHC-Pd-PPh3 complexes 3 were tested against Gram-positive and Gram-negative bacteria to study their biological activity. All the complexes exhibit antibacterial against these organisms. Investigation of the anti-acetylcholinesterase activity of the studied complexes showed that compounds 3a and 3b exhibited moderate activity at 100 μg mL?1 and product 3b is the most active. 相似文献
150.
Density functional theory calculations have been carried out to investigate the [2?+?x] x?=?1, 2, and 3 cycloaddition reactions (paths A, B, and C) of triatomic sulfur (S3) with the C70 fullerene in terms of geometry, energies, and electronic structures. The thiozonation (S3) on the hexagon–hexagon and hexagon–pentagon bonds of the C70 fullerene through 1,3-dipolar reaction, i.e., [2?+?3] cycloaddition, is generally exothermic, while through the chelotrope additions, i.e., [2?+?1] cycloaddition, are endothermic. The results indicate that the 1,3-dipolar cycloaddition is the most preferable path. Having more negative values of reaction energies Er together with the lower barrier heights, thiozonation of the hexagon–hexagon bonds is thermodynamically and kinetically more favorable than hexagon–pentagon ones. Moreover, the addition of thiozone to the hexagon–hexagon bonds near the pole area of the C70 leads to more negative reaction energies. Therefore, it is established that the arrangement and position of C=C bonds play an important role in the thiozonation of C70 fullerene. Thiozonolysis of triatomic sulfur (S3) indicates that S–S bond cleavage has not occurred, instead a sulfur bridge over a C–C bond or a four-membered ring of 1,2-dithietane-1-sulfide is preferred to be formed. 相似文献