▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

/pdf/proton-coupled-electron-transfer-3oyvp0w9qd.pdf

Proton-Coupled Electron Transfer

An integrated approach to the control of ΔE1/2 values, and therefore comproportionation equilibria, through medium effects was delineated for multi-step redox reactions involving cationic products. ΔE1/2 values (defined as E1/22+/1+ − E1/21+/0) of the two one-electron oxidations of bis(fulvalene)dinickel, 1, were measured under 45 different conditions of solvent and supporting electrolyte. The smallest value, 212 mV, was found in anisole/0.1 M [NBu4]Cl and the largest, 850 mV, in CH2Cl2/0.02 M Na[B(C6H3(CF3)2)4]. By systematically changing the solvent properties, the degree of ion-pairing strengths of the supporting electrolyte ions, and the concentration of the electrolytes, a set of ideal properties was found for maximizing ΔE1/2 values involving positively charged electrode products. Most importantly (i) the solvent must be of lower polarity and low donor strength and (ii) the supporting electrolyte must have a weakly coordinating anion (WCA). The contrast in ion-pairing tendencies of 12+ with WCAs (on...

Use of Weakly Coordinating Anions to Develop an Integrated Approach to the Tuning of ΔE1/2 Values by Medium Effects

The electrochemistry, UV−vis spectrophotometry, photoluminescence, and electrogenerated chemiluminescence (ECL) of perylenedicarboxylic imide, perylenetetracarboxylic diimide (PDI), terrylenetetracarboxylic diimide (TDI), and quaterrylenecarboxylic diimide (QDI) were investigated. All compounds undergo two reversible one-electron reductions and one reversible one-electron oxidation reaction. The first reduction potential shifts to less negative values and the potential for oxidation to less positive values for the diimide series with increasing size of the aromatic core. These changes in potential correlate well with orbital energies from molecular orbital calculations. The difference in potential between the first and second reduction waves decreased with increasing distance between the imide groups, so that TDI and QDI show only a single reduction wave, equivalent to a two-electron reduction. These reduction potentials provide estimates for the equilibrium constant for disproportionation of the radical ...

/pdf/electrochemistry-spectroscopy-and-electrogenerated-1gbyds4y3c.pdf

Electrochemistry, Spectroscopy and Electrogenerated Chemiluminescence of Perylene, Terrylene, and Quaterrylene Diimides in Aprotic Solution

Convolution potential sweep voltammetry

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.

https://downloads.hindawi.com/journals/ijelc/2011/816202.pdf

F. Ammar

Papers

Convolution potential sweep voltammetry: II. Multistep nernstian waves

Thermodynamics of successive electron transfers: Internal and solvation enthalpy and entropy variations in a series of polynitro compounds

Development of a novel and efficient biochar produced from pepper stem for effective ibuprofen removal.

Linear sweep voltammetry: kinetic control by charge transfer and/or secondary chemical reactions: II. Reduction of carbonyl compounds

Electrochemical cyclization: II. Intramolecular pinacolization of 1,3-dibenzoylpropane in acetonitrile