The design of multianionic chelating ligands for the production of inorganic oxidizing agents. Osmium coordination chemistry that provides stable potent oxidizing agents and stable potent reducing agents

1984 ◽  
Vol 106 (16) ◽  
pp. 4460-4472 ◽  
Author(s):  
Fred C. Anson ◽  
Judith A. Christie ◽  
Terrence J. Collins ◽  
Robert J. Coots ◽  
Tracy T. Furutani ◽  
...  
Keyword(s):  
Coordination Chemistry ◽  
Reducing Agents ◽  
Chelating Ligands ◽  
Oxidizing Agents

scholarly journals PROTEOLYTIC ENZYMES

1946 ◽  
Vol 29 (4) ◽  
pp. 219-247 ◽  
Author(s):  
David Grob
Keyword(s):  
Proteolytic Enzymes ◽  
Reducing Agents ◽  
Sulfhydryl Groups ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Oxidizing Agents ◽  
Neutral Ph ◽  
Oxidation Reduction ◽  
Antiproteolytic Activity ◽  
Sulfhydryl Compounds

1. The literature on conditions affecting the activity of proteolytic enzymes has been reviewed. 2. Experimental data on the control of the activity of trypsin, leucoprotease, papain, serum antiprotease, leucopeptidase, and pancreatic peptidase have been presented. These data indicate that: (a) The polymorphonuclearleucocytes of the cat contain abundant proteinase and peptidase active at neutral pH; those of the rabbit lack proteinase active at neutral pH. (b) Reducing agents, including several biologically important thiol-sulfhydryl compounds and ascorbic acid, inhibit the activity of leucoprotease and trypsin. For each reductant the degree of inhibition is proportional to the reducing capacity of the medium. (c) p-Aminobenzoic acid, sulfonamides (especially sulfathiazole), and many diphenyl sulfones inhibit the activity of leucoprotease. (d) Serum, plasma, several heavy metals, ammonium salts, asparagine, thiourea, heparin, glutamic acid, tyrothricin, calcium chloride, and bile salts and bile acids also inhibit the activity of leucoprotease, and in most cases of trypsin too. (e) Preparations of tryptic digests of proteins, and egg white trypsin inhibitor, inhibit trypsin to a much greater degree than leucoprotease. (f) Mild oxidizing agents increase the activity of leucoprotease and trypsin. (g) Oxidizing agents and some inhibitors of sulfhydryl groups inhibit the antiproteolytic activity of the serum. It is suggested that serum antiprotease may consist (chiefly) of reducing agents, including thiol-sulfhydryl peptides which exert their antiproteolytic activity by virtue of the presence of sulfhydryl groups. (h) The antiproteolytic activity of the serum is progressively weakened by exposure to a hydrogen ion concentration below pH 6.5 or above pH 9.7. Because of this the pH optima of leucoprotease and trypsin are shifted in the presence of serum from pH of 7 and 8 to pH of 6 to 6.5, and the range of activity of these enzymes is slightly widened, in both acid and alkaline reactions. (i) Reducing agents increase the activity of leucopeptidase and pancreatic peptidase. Serum, sulfathiazole, and thiourea have little or no effect. 3. The significance of the oxidation-reduction system in the control of the activity of leucoprotease, trypsin, serum antiprotease, leucopeptidase, and pancreatic peptidase has been emphasized.

Redox reactions in acetic anhydride

1975 ◽  
Vol 28 (5) ◽  
pp. 991 ◽  
Author(s):  
KC Malhotra ◽  
DS Katoch
Keyword(s):  
Acetic Anhydride ◽  
Redox Reactions ◽  
Reducing Agents ◽  
Iodine Monochloride ◽  
Nitrosyl Chloride ◽  
Oxidizing Agents ◽  
New Compounds

Redox reactions in acetic anhydride have been followed both conductometrically and visually. Chlorine, bromine, iodine, iodine monochloride and nitrosyl chloride have been used as oxidizing agents and phosphorus(III), arsenic(III) and antimony(III) compounds as reducing agents. Some new compounds have been isolated and characterized.

scholarly journals Mono- and Dinuclear Aluminium Complexes Derived from Biguanide and Carbothiamide Ligands

Inorganics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 52
Author(s):  
Maximilian Dehmel ◽  
Helmar Görls ◽  
Robert Kretschmer
Keyword(s):  
Coordination Chemistry ◽  
Solid State ◽  
Coordination Polymer ◽  
Diffraction Analysis ◽  
Crucial Role ◽  
Chelating Ligands ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Solid State Structures

Dianionic N,N-chelating ligands play a crucial role in coordination chemistry, but reports on related complexes remain limited to certain types of ligands. In here, the reactions of two diprotic ligands, i.e., a biguanide and a carbothiamide, with trimethylaluminium, are reported, which give rise to mono- and dinuclear aluminium(III) complexes. In addition, single deprotonation of the diprotic biguanide using potassium bis(trimethylsilyl)amide gives rise to a one-dimensional coordination polymer. All complexes have been fully characterized, and their solid-state structures were determined by single crystal X-ray diffraction analysis.

Chiral Heterocyclic Ligands. VIII. Syntheses and Complexes of New Chelating Ligands Derived From Camphor

1995 ◽  
Vol 48 (9) ◽  
pp. 1549 ◽  
Author(s):  
AA Watson ◽  
DA House ◽  
PJ Steel
Keyword(s):  
Coordination Chemistry ◽  
Transition Metals ◽  
Crystal Structures ◽  
Palladium Complexes ◽  
Chelating Ligands ◽  
Heterocyclic Ligands ◽  
X Ray

The syntheses of 23 new chelating ligands are described. Most of these ligands are derived from the chiral pyrazole (1) which has been linked to a variety of heterocycles , namely pyridine, pyrimidine, pyridazine, isoxazole , benzimidazole, thiophen and furan. In certain cases the parent achiral analogues have also been prepared. Preliminary studies of the coordination chemistry of these ligands with selected transition metals have been carried out. The X-ray crystal structures of palladium complexes of isoxazole- and thiophen-containing ligands have also been determined.

THE ELECTROCHEMICAL MECHANISM OF SULFIDE SELF‐POTENTIALS

Geophysics ◽  
1960 ◽  
Vol 25 (1) ◽  
pp. 226-249 ◽  
Author(s):  
Motoaki Sato ◽  
Harold M. Mooney
Keyword(s):  
Water Table ◽  
Potential Drop ◽  
Reducing Agents ◽  
Oxidation Potential ◽  
Simultaneous Reduction ◽  
Oxidizing Agents ◽  
Ore Body ◽  
Oxidation Reduction ◽  
Ohmic Potential Drop ◽  
Different Depths

Self‐potentials associated with a sulfide ore body result from the ohmic potential drop within the country rocks. The electric current is produced by separate but simultaneous reduction of oxidizing agents near the surface and oxidation of reducing agents at depth. The ore does not participate directly in either reaction, but serves as a conductor to transfer the electrons from the reducing agents to the oxidizing agents. The possibility for the above reactions to occur depends upon differences in oxidation potential of ground waters at different depths. In the zone of weathering, the oxidation potential is controlled by the reduction mechanism of oxygen, and ranges in value from 0.2 to 0.7 volt (on the hydrogen scale). If the ore tends to oxidize at some lower potential, then the latter is the available one. In the zone beneath the water table, the potential is probably controlled by the oxidation‐reduction equilibria of iron‐rich minerals, and ranges in value from 0 to −0.3 volt. The available potential is independent of ore type. The maximum potential difference available to produce natural currents is estimated at: graphite 0.8, pyrite 0.7, covellite 0.6, chalcocite 0.5, galena 0.3 volt. Self‐potentials will be large if the ore body (1) is composed of minerals difficult to oxidize, (2) has low electrical resistance (physical continuity together with low resistivity), (3) extends vertically across the water table, and (4) exists close to the surface.

scholarly journals Hydrogen bonding patterns in hydroxyamidine/α-aminonitrone (AMOX) type compounds

2014 ◽  
Vol 70 (a1) ◽  
pp. C539-C539
Author(s):  
Mihaela Cibian ◽  
Sofia Derossi ◽  
Denis Spasyuk ◽  
Janaina Ferreira ◽  
Garry Hanan
Keyword(s):  
Hydrogen Bonding ◽  
Coordination Chemistry ◽  
Crystal Engineering ◽  
Substituent Effects ◽  
Design Tool ◽  
Supramolecular Interactions ◽  
Chelating Ligands ◽  
Hydrogen Bonding Pattern ◽  
Bonding Patterns

N,N'-Disubstituted hydroxyamidines/ α-aminonitrones (AMOXs) present high steric and electronic modularity (substituents can be varied on the central C atom and/or on the N atoms) resulting in precise electronic tunability, enhanced by the delocalization on the amidine backbone. They are good chelating ligands, forming stable 5-membered chelate rings with metal ions, and they also present hydrogen bonding capacity. [1] In our research, we exploit these properties by investigating their incorporation into supramolecular assemblies based on coordination chemistry and/ or hydrogen bonding. Herein, we present the synthesis and the structural characterization of different mono- and bis-AMOX type compounds. [2] The analysis of the hydrogen bonding patterns found in each case is highlighted (Figure 1), in an effort to identify factors (e.g. substituent effects: sterics and/ or electronics, other type of supramolecular interactions) that are generating specific hydrogen-bonding patterns. Understanding and rationalizing such a cause – effect relationship is of paramount importance in order to efficiently use hydrogen bonding as a crystal engineering design tool. Figure 1. Type of hydrogen bonding pattern in AMOX type compounds. [3]

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