scholarly journals Electrochemical Reduction of Quinones in Different Media: A Review

2011 ◽  
Vol 2011 ◽  
pp. 1-22 ◽  
Author(s):  
Partha Sarathi Guin ◽  
Saurabh Das ◽  
P. C. Mandal
Keyword(s):  
Electron Flow ◽  
Biological Systems ◽  
Ion Pair ◽  
Pair Formation ◽  
Transfer Reactions ◽  
Intermolecular Hydrogen Bonding ◽  
Reaction Conditions ◽  
Photosynthetic Electron Flow ◽  
The Media ◽  
As Toxicity

The electron transfer reactions involving quinones, hydroquinones, and catechols are very important in many areas of chemistry, especially in biological systems. The therapeutic efficiency as well as toxicity of anthracycline anticancer drugs, a class of anthraquinones, is governed by their electrochemical properties. Other quinones serve as important functional moiety in various biological systems like electron-proton carriers in the respiratory chain and their involvement in photosynthetic electron flow systems. The present paper summarizes literatures on the reduction of quinones in different solvents under various conditions using different electrochemical methods. The influence of different reaction conditions including pH of the media, nature of supporting electrolytes, nature of other additives, intramolecular or intermolecular hydrogen bonding, ion pair formation, polarity of the solvents, stabilization of the semiquinone and quinone dianion, catalytic property, and adsorption at the electrode surface, are discussed and relationships between reaction conditions and products formed have been presented.

Elektronentransfer und Ionenpaar-Bildung, 47 [1] Titrationen von 1,2,4,5-Tetracyanbenzol und 7,7,8,8-Tetracyan-p-chinodimethan mit Natriummetall in aprotischen Lösungen / Electron Transfer and Ion Pair Formation, 47 [ 1 ] Titrations of 1,2,4,5-Tetracyanobenzene and 7,7,8,8-Tetracyano-p-quinodimethane with Sodium Metal in Aprotic Solutions

1996 ◽  
Vol 51 (9) ◽  
pp. 1215-1221 ◽  
Author(s):  
Hans Bock ◽  
Markus Kleine
Keyword(s):  
Electron Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Transfer Reactions ◽  
The Novel ◽  
Band Shape ◽  
Novel Technique ◽  
Sodium Metal ◽  
Mndo Calculations ◽  
Donor Acceptor

In an especially designed and sealed glass apparatus, a combination of UV/VIS and ESR spectroscopy measurements are performed to follow electron transfer reactions in aprotic (cH⊕ < 0,1 ppm) solution. For the sodium metal reductions of the tetracyano-substituted title compounds, the novel technique provides the following detailed information: 1,2,4,5- tetracyanobenzene is uniformly reduced to its radical anion, for which additional geometryoptimized MNDO calculations predict an already significant cyanine disortion. For 7,7,8,8- tetracyano-p-quinodimethane, UV/VIS band shape analysis allows to detect in the saturated THF reduction solution the 16300 cm-1 absorption of the donor/acceptor complex formed in the equilibrium TCNQ·⊖ + TCNQ ⇆ {TCNQ·⊖···TCNQ}, which according to a literature search has been crystallized and structurally characterized in paramagnetic salts such as [Me2⊕ (TCNQ·⊖)2(TCNQ)].

scholarly journals DETERMINATION OF MIANSERIN USING TROPAEOLIN-OOO BY ION PAIR FORMATION

2019 ◽  
Vol 11 (1) ◽  
pp. 168 ◽  
Author(s):  
Giri Prasad Gorumutchu ◽  
Venkata Nadh Ratnakaram
Keyword(s):  
Treatment Process ◽  
Ion Pair ◽  
Pair Formation ◽  
Reaction Conditions ◽  
Organic Layers ◽  
Ich Guidelines ◽  
Relative Standard ◽  
Satisfactory Precision ◽  
Pre Treatment

Objective: The present study was aimed at the development of a simple visible spectrophotometric method for the assay of mianserin, a drug used for the treatment of depression.Methods: The method was developed using tropaeolin-ooo (TPooo) as an ion associative complex forming a chromophore. Developed the chromophore by sequential mixing of aqueous solutions of mianserin, hydrochloric acid, and TPooo. Chromophore was extracted into an organic solvent (chloroform) and absorbance values of organic layers were measured. As per the existing guidelines of an international conference on harmonization (ICH), various parameters of the method were tested for validation.Results: At the optimized reaction conditions, the formed chromophore (λ max 524 nm) was stable and sensitive. Regression analysis (r>0.9999) shows that the plotted calibration curve exhibits good linearity in the studied range of concentration (4–24 µg/ml). Accuracy of the method was evident from the % recovery values (99.50–99.87 range). Satisfactory precision (both intra and inter day) for the proposed method was clear as ranges of percentage of relative standard deviation (%RSD) values were 1.382-1.781 and 1.128-1.765 respectively. Since RSD is less than 2 %, this method was reproducible and accurate.Conclusion: Due to lack of pre-treatment process for this method, it was simple. All the tested parameters of the method were validated as per ICH guidelines.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Extraction of organic acids by ion-pair formation with tri-n-octylamine

1985 ◽  
Vol 178 ◽  
pp. 189-195 ◽  
Author(s):  
M. Puttemans ◽  
L. Dryon ◽  
D.L. Massart
Keyword(s):  
Organic Acids ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation

Non-Invasive Monitoring of the Light-Induced Cyclic Photosynthetic Electron Flow during Cold Hardening in Wheat Leaves

2006 ◽  
Vol 61 (9-10) ◽  
pp. 734-740 ◽  
Author(s):  
Simona Apostol ◽  
Gabriella Szalai ◽  
László Sujbert ◽  
Losanka P. Popova ◽  
Tibor Janda
Keyword(s):  
Winter Wheat ◽  
Electron Flow ◽  
Wheat Variety ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Light Conditions ◽  
Non Invasive ◽  
Photosynthetic Electron Flow ◽  
Temperature Hardening ◽  
Wheat Leaves

AbstractThe effect of irradiance during low temperature hardening was studied in a winter wheat variety. Ten-day-old winter wheat plants were cold-hardened at 5 °C for 11 days under light (250 μmol m-2 s-1) or dark (20 μmol m-2 s-1) conditions. The effectiveness of hardening was significantly lower in the dark, in spite of a slight decrease in the Fv/Fm chlorophyll fluorescence induction parameter, indicating the occurrence of photoinhibition during the hardening period in the light. Hardening in the light caused a downshift in the far-red induced AG (afterglow) thermoluminescence band. The faster dark re-reduction of P700+, monitored by 820-nm absorbance, could also be observed in these plants. These results suggest that the induction of cyclic photosynthetic electron flow may also contribute to the advantage of frost hardening under light conditions in wheat plants.

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