scholarly journals INVESTIGATION OF COORDINATION PROPERTIES OF 5,10,15,20-TETRA(4-OH-PHENYL) PORPHYRIN IN ACETONITRILE AND DIMETHYLFORMAMIDE

2017 ◽  
Vol 60 (6) ◽  
pp. 65
Author(s):  
Anna O. Plotnikova ◽  
Yulia B. Ivanova ◽  
Nugzar Zh. Mamardashvili
Keyword(s):  
Zinc Complex ◽  
Dissociation Constants ◽  
Spectrophotometric Titration ◽  
Free Medium ◽  
Kinetic Rate ◽  
Coordination Properties ◽  
Kinetics Of ◽  
Basic Dissociation ◽  
Ionic Forms ◽  
Influence Of Solvent

In the present work the reactions of basic interaction of 5,10,15,20-tetra(4-OH-phenyl) porphyrin in acetonitrile with the perchloric acid are studied by the method of spectrophotometric titration. And the chemical kinetics of ligand with zinc acetate in the dimethylformamide was carried out. The constant of the basic dissociation of the protonated acids of 5,10,15,20-tetra(4-OH-phenyl) porphyrin and kinetic parameters of the reaction of the formation of the zinc complex was obtained. The comparative analysis of our own obtained data and literature data according to the basic and coordination properties of 5,10,15,20-tetra(4-OH-phenyl) porphyrin and 5,10,15,20-tetrapheny porphyrin in acetonitrile and dimetilforamide in the range of 298-333K was carried out, which made it possible to draw a number of the interesting conclusions, which are concerned with the stabilization of the ionic forms of ligand in the acetonitrile and the dimethylformamide and the influence of solvent on the depth of the protonation of ligand and the kinetic rate of the formation of the corresponding zinc complexes. It is shown that the stabilization of the ionic forms of ligand upon transfer from the acetonitrile to dimethylformamide reduces the depth of the protonation of ligand, which is reflected in the decrease of the values of the dissociation constants of the cation forms of porphyrin, and the kinetic rate and the corresponding power expenditures for the reaction of the formation of ZnT(4-OH-Ph)P. It is shown that reactivity of ligand in the dipolar proton-free medium can be regulated by a change in the properties of this medium, which makes it possible to forecast the processes of the synthesis of compounds with the assigned properties.Forcitation:Plotnikova A.O., Ivanova Yu.B., Mamardashvili N.Zh. Investigation of coordination properties of 5,10,15,20-tetra(4-OH-phenyl) porphyrin in acetonitrile and dimethylformamide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 65-71.

Modeling of sorption kinetics of U(VI) micro-quantities nanostructured materials with anatase mesoporous structures

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Veniamin Zheleznov ◽  
Aleksey Golikov ◽  
Tatiana Sokolnitskaya ◽  
Sergey Ivannikov
Keyword(s):  
Nanostructured Materials ◽  
Sorption Kinetics ◽  
Uranyl Ion ◽  
Competitive Sorption ◽  
Hydroxyl Groups ◽  
Complex Ions ◽  
The Stability ◽  
Kinetics Of ◽  
Mesoporous Structures ◽  
Ionic Forms

Abstract The sorption kinetics of uranyl ions micro-quantities from fluoride solutions by nanostructured materials with anatase mesoporous structures has been studied. Using the model of competitive sorption of ions and positively charged complexes of uranyl ion on deprotonated hydroxyl groups of an anatase, kinetic curves of changes in the ratio of ionic forms of uranium in solution were calculated. Modeling was carried out under the assumption of a two-stage mechanism of uranium complex ions sorption. The modeling considered the influence of the uranyl ion carbonate complexes formation. The shift in equilibrium among ionic forms of uranyl correlates with the stability of the complexes in solution.

The comparative chemistry of ammine and methylamine complexes of rhodium(III) and cobalt(III)

1977 ◽  
Vol 55 (17) ◽  
pp. 3166-3171 ◽  
Author(s):  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Electron Donor ◽  
Dissociation Constants ◽  
Base Hydrolysis ◽  
Acid Dissociation ◽  
Rate Coefficients ◽  
Acid Dissociation Constants ◽  
First Order ◽  
Kinetics Of

For the aquation of (CH3NH2)5RhCl2+, the first order rate coefficients are represented by ΔHaq* = 101.9 kJ mol−1 and ΔSaq* = −50.2 JK−1 mol−1 in 0.1 M HClO4, while for base hydrolysis the rate is first order in [(CH3NH2)5RhCl2+] and [OH−] at ionic strength 0.10 M and the rate coefficients (in M−1 s−1) are represented by ΔHOH*> = 108.6 kJ mol−1 and ΔSOH* = 74.1 J K−1 mol−1. Acid dissociation constants are reported for (RNH2)5MOH23+ (R = H or CH3; M = Rh or Co), and these, combined with spectral data, show CH3NH2 to be a poorer electron donor than NH3 in complexes of this type, contrary to expectations. The comparative kinetics of reactions of (RNH2)5MCl2+ support the assignment of an Ia mechanism to aquation when M = Rh or Cr, Id to aquation when M = Co, and Dcb for base hydrolysis in all these cases.

scholarly journals Guanidine Hydrochloride Inhibits the Generation of Prion “Seeds” but Not Prion Protein Aggregation in Yeast

2002 ◽  
Vol 22 (15) ◽  
pp. 5593-5605 ◽  
Author(s):  
Frédérique Ness ◽  
Paulo Ferreira ◽  
Brian S. Cox ◽  
Mick F. Tuite
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Chaperone ◽  
Guanidine Hydrochloride ◽  
Free Medium ◽  
Seed Number ◽  
Cycle Model ◽  
Yeast Prions ◽  
Independent Process ◽  
Kinetics Of ◽  
Number Of Seeds

ABSTRACT [PSI +] strains of the yeast Saccharomyces cerevisiae replicate and transmit the prion form of the Sup35p protein but can be permanently cured of this property when grown in millimolar concentrations of guanidine hydrochloride (GdnHCl). GdnHCl treatment leads to the inhibition of the replication of the [PSI +] seeds necessary for continued [PSI +] propagation. Here we demonstrate that the rate of incorporation of newly synthesized Sup35p into the high-molecular-weight aggregates, diagnostic of [PSI +] strains, is proportional to the number of seeds in the cell, with seed number declining (and the levels of soluble Sup35p increasing) in the presence of GdnHCl. GdnHCl does not cause breakdown of preexisting Sup35p aggregates in [PSI +] cells. Transfer of GdnHCl-treated cells to GdnHCl-free medium reverses GdnHCl inhibition of [PSI +] seed replication and allows new prion seeds to be generated exponentially in the absence of ongoing protein synthesis. Following such release the [PSI +] seed numbers double every 20 to 22 min. Recent evidence (P. C. Ferreira, F. Ness, S. R. Edwards, B. S. Cox, and M. F. Tuite, Mol. Microbiol. 40:1357-1369, 2001; G. Jung and D. C. Masison, Curr. Microbiol. 43:7-10, 2001), together with data presented here, suggests that curing yeast prions by GdnHCl is a consequence of GdnHCl inhibition of the activity of molecular chaperone Hsp104, which in turn is essential for [PSI +] propagation. The kinetics of elimination of [PSI +] by coexpression of a dominant, ATPase-negative allele of HSP104 were similar to those observed for GdnHCl-induced elimination. Based on these and other data, we propose a two-cycle model for “prionization” of Sup35p in [PSI +] cells: cycle A is the GdnHCl-sensitive (Hsp104-dependent) replication of the prion seeds, while cycle B is a GdnHCl-insensitive (Hsp104-independent) process that converts these seeds to pelletable aggregates.

Kinetics of methanolysis of 1-(2-halogeno and 2,6-dihalogenobenzoyl)-3-(4-chlorophenyl)ureas

1989 ◽  
Vol 54 (5) ◽  
pp. 1363-1369
Author(s):  
Jaromír Kaválek ◽  
Lubomír Kacetl ◽  
Marcela Kaválková
Keyword(s):  
Dissociation Constants ◽  
Steric Effects ◽  
Kinetics Of

The methanolysis kinetics has been measured of 1-(2,6-difluorobenzoyl)-3-(4-chlorophenyl)urea (a larvicidal insecticide Dimilin) and of four other mono- and dihalogenobenzoyl derivatives. Polar and steric effects of halogen on the rate and dissociation constants is discussed.

Effect of chloride ions on the kinetics of nitrobenzene reduction by powdered iron

2006 ◽  
Vol 60 (5) ◽  
Author(s):  
M. Heželová ◽  
L’. Pikna ◽  
D. Kladeková ◽  
L. Lux
Keyword(s):  
Specific Surface ◽  
Reaction System ◽  
Particulate Material ◽  
Surface Reactivity ◽  
Chloride Ions ◽  
Free Medium ◽  
Iron Particles ◽  
Nitrobenzene Reduction ◽  
Powder Particles ◽  
Kinetics Of

AbstractThe effect of different chloride ions concentrations on the reactivity of iron particles was studied using chronopotentiometry. It was found that the increase of Cl− ions concentration accelerated anodic dissolution of iron, thus enhancing its surface reactivity. This fact was confirmed also by the rate of nitrobenzene reduction by iron particles. The reactivity of powder particles of various sizes, hence of different specific surface, was investigated in chloride-free and chloride-containing acetate buffer electrolytes. Experimental results indicated that the rate of nitrobenzene reduction in the presence of chloride ions in the reaction system is faster in comparison with the rate in chloride-free medium for each studied grain fraction of particulate material.

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