Ferrocene-ferricinium coupl

A combined computational and electrochemical investigation revealed that arylated TEEs may also have potential as electrochemically driven molecular switches [27]. The electrochemical studies showed that the first reduction potentials of mono- and bis(4-nitrophenyl)-substituted TEEs occur at similar values (around —1.35 to —1.38 V versus the ferrocene/ ferricinium couple, Fc/Fc+) on steps involving one and two electrons, respectively. Moreover, the first reduction potential of nitrophenyl-substituted TEEs is hardly affected by the presence of other aryl substituents, such as the DMA donor groups, attached to the TEE frame. These findings suggest that the nitrophenyl redox centers behave as independent redox centers. However, ab initio calculations on singly-reduced trans-13 (Figure 4)... 

The caesium assumption is popular with electrochemists and gives results comparable with the ferrocene-ferricinium assumption (ii) at least for solutions in water, formamide, methanol, and acetonitrile (Kolthoff, 1964 Strehlow, 1952 Koepp et al., 1960). However, we favour the tetraphenylarsonium-tetraphenylboride assumption of Grunwald et al. (1960) because it makes a more satisfactory allowance for size effects, such as making and breaking of solvent structure, while still preserving the attractive features, as to electrostatic solvation, possessed by the ferrocene-ferricinium couple and the caesium cation. 

Kolthoff and Thomas measured e.m.f. s of cells of the type (XVII) where M M+ represents a redox couple such as trisip-phenanthroline) Fe(III) rrw(o-phenanthroline)Fe(II) couple (abbreviated Fe(phen) Fe(phen)f ), or the ferrocene-ferricinium couple (abbreviated Fe(C5H5)2 Fe(C5H5)2). Measurements were made in the presence and absence of supporting electrolyte (Et4NC104). E values were obtained from... 

These ligands form different host-guest complexes, 39, and the redox potential of the ferrocene-ferricinium couple is sensitive to coronand complexation by alkali metals [84a]. 

A three-electrode cell with one or two compartments. If the potentiostatic or potentiodynamic method is used, a reference electrode is necessary. The reference electrode may be simply a silver wire, pseudoreference. Its potential is not particularly stable and it should be standardized before or after every use by measuring a cyclic voltammogram of ferrocene. The redox potential of the ferrocene-ferricinium couple is well known in all common solvents and hence this couple is generally used as a potential standard. 

Figure 1 displays derivative cyclic voltammograms for the oxidation of Cp Mn(CO)2(NCMe) (1 left) and Cp Mn(CO)2(Pl%3) (2 right) at a voltage sweep rate v - 0.2 V/s. Cyclic voltammetry peak potentials correspond to the intersections between the DCV curves and the base line. The reversible potentials for the oxidation of 1 and 2, taken as the midpoints between the anodic and cathodic CV peaks, are located at -0.12 and +0.22 V vs the ferrocene/ferricinium couple (Fc), respectively. The unity ratio of the cathodic to anodic derivative peak currents demonstrates the chemical reversibility of the 1/1 and 2/2- couples. 

Electrosynthesis of the polythiopene was realized on an indium-tin-oxide (ITO) electrode (glass blade covered with an indium-doped tin-oxide film). Before conducting the experiment, each electrode was cleaned by ultrasonication for 10 min in different solvents (acetone, dichloromethane, ether). Electrochemical experiments were performed in a three-compartment cell. The working electrode was the ITO electrode, the counter electrode was a Pt wke, and the reference electrode was an aqueous-saturated calomel electrode (E°/SCE = E°/NHE — 0.2412 V) with a salt bridge containing the supporting electrode. The SCE electrode was checked against the ferrocene/ferricinium couple (E = -1-0.405 V/SCE) before and after each experiment. 

Solvation coefficients of ions [such as H, Ag etc.] in aqueous-organic mixtures 269 evaluation by means of the ferrocene-ferricinium couple... 

Figures 3b-3d show the progressive decrease in the enzyme activity with time at room temperature. The two hour voltammogram (Figure 3d) approaches that obtained for the ferrocene/ferricinium couple on the...

Nafion, a perfluorinated sulfonated polymer introduced by Rubinstein and Bard 4 5, which is able to immobilize electroactive cations by electrostatic binding, has been coated on gold electrodes in order to display the electrochemical behaviours of the ferrocene-ferricinium couple . Ru(NH3)e and Ru(bpy)3 have also been used as redox centers ". Nafion has been proposed to modify microvoltammetric electrodes for in vivo use . 

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