scholarly journals Redox Properties of Mononuclear Dicarbonyl and Carbonylphosphine Rhodium (I) Complexes Containing β-diketonate Ligands

2019 ◽  
pp. 413-422
Author(s):  
Galina V. Burmakina ◽  
Victor V. Verpekin ◽  
Dmitry V. Zimonin ◽  
Oleg S. Chudin ◽  
Tatyana S. Nedelina ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Redox Properties ◽  
Electrochemical Methods ◽  
Mercury Electrodes

The redox properties of mononuclear dicarbonyl and carbonylphosphine rhodium (I) complexes (CO)(L)Rh(RC(O)CHC(O)R’) with chelate β-diketonate ligands (L = CO, PPh3; R, R’ = Me, Ph; CF3, C4H3S) were studied by electrochemical methods at platinum, glassed carbon and dropping mercury electrodes in acetonitrile. Schemes of their redox reactions were established

Direct electrochemistry of nanoparticulate Fe2O3 in aqueous solution and adsorbed onto tin-doped indium oxide

2001 ◽  
Vol 73 (12) ◽  
pp. 1885-1894 ◽  
Author(s):  
Katy J. McKenzie ◽  
Frank Marken
Keyword(s):  
Indium Oxide ◽  
Redox Reactions ◽  
Direct Detection ◽  
Direct Electrochemistry ◽  
Redox Properties ◽  
Fe2o3 Nanoparticles ◽  
Solution Composition ◽  
Electrode Surfaces ◽  
Buffer Solutions ◽  
Electrochemical Processes

Nanoparticulate iron oxides occur naturally, for example, in soil, water, and in the cytoplasm of living cells. The redox properties and detection of these nanoparticles are therefore of considerable importance. Understanding and mimicking nanoparticle-based redox reactions may lead to new types of water-based electrochemical processes. In this study, the electrochemical detection of 4­5 nm diameter Fe2O3 nanoparticles dissolved in aqueous buffer solutions is investigated as a model system. Voltammetric experiments with nanoparticulate Fe2O3 are reported based on two complementary approaches: (i) Fe2O3 nanoparticles adsorbed onto tin-doped indium oxide (ITO) electrodes are shown to give well-defined voltammetric reduction responses and (ii) hydrodynamic voltammety in the presence of fast (24 kHz ultrasound-enhanced) mass transport is shown to allow the direct detection of Fe2O3 nanoparticles in solution. Both the adhesion and the electrochemical reactivity of Fe2O3 nanoparticles at ITO electrode surfaces are strongly affected by the solution composition and the pH.

scholarly journals The Microbiota–Gut–Brain Axis Heart Shunt Part I: The French Paradox, Heart Disease and the Microbiota

2020 ◽  
Vol 8 (4) ◽  
pp. 490 ◽  
Author(s):  
Mark Obrenovich ◽  
Bushra Siddiqui ◽  
Benjamin McCloskey ◽  
V. Prakash Reddy
Keyword(s):  
Heart Disease ◽  
Neurodegenerative Diseases ◽  
Redox Reactions ◽  
Close Association ◽  
Cerebrovascular Diseases ◽  
Mechanisms Of Action ◽  
Whole Grains ◽  
Redox Properties ◽  
Health Promoting ◽  
French Paradox

It has been well established that a vegetarian and polyphenol-rich diet, including fruits, vegetables, teas, juices, wine, indigestible fiber and whole grains, provide health-promoting phytochemicals and phytonutrients that are beneficial for the heart and brain. What is not well-characterized is the affect these foods have when co-metabolized within our dynamic gut and its colonizing flora. The concept of a heart shunt within the microbiota-gut-brain axis underscores the close association between brain and heart health and the so-called “French paradox” offers clues for understanding neurodegenerative and cerebrovascular diseases. Moreover, oxidation-redox reactions and redox properties of so-called brain and heart-protective foods are underappreciated as to their enhanced or deleterious mechanisms of action. Focusing on prodromal stages, and common mechanisms underlying heart, cerebrovascular and neurodegenerative diseases, we may unmask and understanding the means to better treat these related diseases.

A Critical Evaluation of the Redox Properties of Uranium, Neptunium and Plutonium Ions in Acidic Aqueous Solutions

1999 ◽  
Vol 71 (9) ◽  
pp. 1771-1807 ◽  
Author(s):  
Sorin Kihara ◽  
Zenko Yoshida ◽  
Hisao Aoyagi ◽  
Kohji Maeda ◽  
Osamu Shirai ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Redox Reactions ◽  
Critical Evaluation ◽  
Redox Properties ◽  
Redox Processes ◽  
Redox Potentials ◽  
Electrode Processes ◽  
Reversible Redox ◽  
Reduction Mechanisms ◽  
Current Potential

Standard redox potentials, E0s, and redox processes of U, Np and Pu ions in acidic aqueous solutions are reviewed and evaluated critically. The E0sof reversible redox processes, MO22+/MO2+ and M4+/M3+ (M: U, Np or Pu) adopted are those proposed mainly by Riglet et al. on the basis of the precise correction of formal potentials, E0's, according to the improved theoretical approach to estimate the activity coefficient. Electrode processes of the U, Np and Pu ions are discussed in terms of current-potential curves, measured so far by polarography, voltammetry or flow coulometry. Special attention is payed to the irreversible MO2+/M4+ reactions. Disproportionation reactions of MO2+ are also discussed. New substances are introduced as intermediates during reductions of MO2+ to M4+ or disproportionations of MO2+.CONTENTSIntroductionStandard redox potentials for uranium, neptunium and plutonium ions in acidic aqueous solutions2.1 Evaluation of E0 from E0' determined by electrochemical measurements2.2 Temperature dependence of E0Redox reactions of uranium, neptunium and plutonium in acidic aqueous solutions investigated by polarography or voltammetry3.1 Uranium3.2 Neptunium3.3 Plutonium3.4 Disproportionation of NpO2+, PuO2+, Np4+ and Pu4+3.5 Reduction of MO2+ and reduction intermediatesRedox reactions of uranium, neptunium and plutonium in acidic aqueous solutions investigated by flow coulometry4.1 Electrode processes of the uranium, neptunium and plutonium ions investigated by flow coulometry at the column electrode at the column electrode4.2 Disproportionation of MO2+ during the electrolysis by flow coulometry4.3 Reduction mechanisms of MO2+ (M = Np or Pu) and reduction intermediates investigated by flow coulometryConclusionsList of abbreviationsAppendixReferences

The effect of pH and complexation on redox reactions between RS• radicals and flavins

1984 ◽  
Vol 62 (1) ◽  
pp. 171-177 ◽  
Author(s):  
Rizwan Ahmad ◽  
David A. Armstrong
Keyword(s):  
Redox Potential ◽  
Linear Function ◽  
Redox Reactions ◽  
Flavin Adenine Dinucleotide ◽  
Protonated Form ◽  
Redox Properties ◽  
The Other ◽  
Effect Of Ph ◽  
Other Hand ◽  
High Redox Potential

Elementary considerations indicate that thiol radicals, RS•, should have a high redox potential [Formula: see text][Formula: see text]However, the equilibrium [4],[Formula: see text]which is established in the presence of excess RS−, would convert RS•to [Formula: see text] which is a reducing species. Experimentally it was demonstrated that thiol radicals made by γ radiolysis of β-mercaptoethanol solutions effected two-electron oxidation of dihydroflavin FlH2 at pH 6.3 and of FlH− at pH 8. On the other hand, [Formula: see text] readily reduced Fl to FlH2 or FlH− as expected. At pH 9, photostationary states were established after a few minutes radiolysis and the ratios [FlH−]ss/[Fl]ss were a function of [Formula: see text] The main reactions occurring were:[Formula: see text]The values of k19 and k22 were both large. The ratio k19/k22 was ∼0.8 for lumiflavin and ∼0.3 for flavin adenine dinucleotide. The cyclic disulphide anions of lipoamide and dithiothreitol [Formula: see text] also effected two-electron reductions of flavins. However, the protonated form of [Formula: see text] oxidized FlH2, and the photostationary ratio [FlH−]ss/[Fl]ss was an approximate linear function of [Formula: see text]. The implications of the observed changes in redox properties of sulphur radicals on complexation with RS− and protonation were briefly considered.Des considérations élémentaires indiquent que les radicaux thiyles, RS•, doivent avoir un potentiel rédox élevé [Formula: see text][Formula: see text]

Investigations on V(IV)/V(V) and V(II)/V(III) redox reactions by various electrochemical methods

2005 ◽  
Vol 139 (1-2) ◽  
pp. 321-324 ◽  
Author(s):  
Gaku Oriji ◽  
Yasushi Katayama ◽  
Takashi Miura
Keyword(s):  
Redox Reactions ◽  
Electrochemical Methods

THE DETERMINATION OF KINETIC PARAMETERS OF REDOX REACTIONS FROM CURRENT–POTENTIAL CURVES

1959 ◽  
Vol 37 (1) ◽  
pp. 238-246 ◽  
Author(s):  
J. E. B. Randles
Keyword(s):  
Kinetic Parameters ◽  
Redox Reactions ◽  
Mercury Electrode ◽  
Dropping Mercury Electrode ◽  
Mercury Electrodes ◽  
Rotating Electrodes ◽  
Current Potential ◽  
Potential Curves ◽  
Good Agreement

Methods are suggested for calculating kinetic parameters of moderately rapid redox reactions from current–potential curves obtained with (a) rotating electrodes or stationary electrodes in stirred solutions, (b) dropping mercury electrodes. Experimental results for the V2+/V3+ reaction at a dropping mercury electrode are presented and compared with a-c. impedance measurements on the same system. It is found that there is a good agreement between the kinetic parameters obtained by the two methods when the current–potential curves are interpreted with the aid of Koutecky's theory of diffusion to a dropping mercury electrode.

scholarly journals Phenylvinylidene RePt Complexes Containing Diphenylphosphine Ligands at the Platinum Atom: Synthesis, IR, NMR Spectroscopic and Electrochemical Properties

2020 ◽  
pp. 385-394
Author(s):  
Oleg S. Chudin ◽  
Victor V. Verpekin ◽  
Galina V. Burmakina ◽  
Dmitry V. Zimonin ◽  
Alexander A. Kondrasenko ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Spectroscopic Data ◽  
Redox Reactions ◽  
Redox Properties ◽  
Molecular Structures ◽  
Platinum Atom ◽  
First Time

The μ-phenylvinylidene complexes Cp(CO)2RePt(μ-C=CHPh)(PPh2H)(L) [L = PPh3 (1), P(OPri)3 (2)] were synthesized for the first time. Their IR, NMR spectroscopic and redox properties were studied. Based on IR, NMR spectroscopic data their molecular structures were proposed. The pathways of redox-reactions of the complexes were determined

Medicinal Chemistry Meets Electrochemistry: Redox Potential in the Role of Endpoint or Molecular Descriptor in QSAR/QSPR

2020 ◽  
Vol 20 (14) ◽  
pp. 1341-1356
Author(s):  
Karel Nesměrák
Keyword(s):  
Redox Potential ◽  
Redox Reactions ◽  
Medicinal Chemistry ◽  
Molecular Descriptor ◽  
Redox Properties ◽  
Physiological Effects ◽  
Therapeutic Activity ◽  
The Subject ◽  
The Relationship

Many biochemical reactions are based on redox reactions. Therefore, the redox potential of a chemical compound may be related to its therapeutic or physiological effects. The study of redox properties of compounds is a domain of electrochemistry. The subject of this review is the relationship between electrochemistry and medicinal chemistry, with a focus on quantifying these relationships. A summary of the relevant achievements in the correlation between redox potential and structure, therapeutic activity, resp., is presented. The first part of the review examines the applicability of QSPR for the prediction of redox properties of medically important compounds. The second part brings the exhaustive review of publications using redox potential as a molecular descriptor in QSAR of biological activity. Despite the complexity of medicinal chemistry and biological reactions, it is possible to employ redox potential in QSAR/QSPR. In many cases, this electrochemical parameter plays an essential but rarely absolute role.

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