Ferrocene cyclic voltammetric response

Figure 5. Cyclic voltammetric response of Ferrocene - (A) in CH2CI2, (B) with added CN-[P], (C) after addition of Cr(CN-[P])6.

FIGURE 5.25. Avidin-biotin construction of a monolayer glucose oxidase electrode with an attached ferrocenium cosubstrate and cyclic voltammetric response in a phosphate buffer (pH 8) at 25°C and a scan rate of 0.04 V/s. a attached ferrocene alone, h In the presence of 0.5 M glucose, c Variation of the inverse of the plateau current with the inverse of substrate concentration. Adapted from Figure 1 in reference 24, with permission from the American Chemical Society. 

As far as the electrode adsorption phenomena caused by P° y erro cenes are concerned, Figure 26 shows the cyclic voltammetric response o the illustrated fluorenyl-ferrocene polymer (Fw 7000). 

It exhibits a single oxidation process (Ea = + 0.59 V, vs. SCE) affected by some adsorption problems. These adsorption phenomena, which typically affect the electrochemical response of these derivatives, sometimes make it difficult to ascertain by controlled potential coulometry the effective number of electrons involved in the oxidation step. In this case, the (approximate) number of electrons involved per molecule of dendrimer, nd, can be roughly calculated by comparing the cyclic voltammetric responses of the dendrimer with that of the ferrocene monomer using the following empirical equation.27,40... 

Figure 33 shows the cyclic voltammetric response of the 8-Fc derivative. It gives rise to two separate reversible oxidations (each one involving four electrons) separated by 0.19 V. This means that the overall oxidation proceeds through two separated steps each one involving four alternate ferrocene units. 

Cyclic voltammetric response of a ferrocene molecule (a) initial (b) after cation complexation... 

In order to illustrate the possibly extended redox aptitude of the ferrocene complexes, Figure 7 shows the cyclic voltammetric response of the ferrocenyl-terpyridine-Ru(II) complex [Fc -(C6H4)-terpy-Ru-terpy-(C6H4)-Fc ]2+ [Fc = (fj5-C5Me4H)Fe(i 5-C5Me4)].5... 

Figure 18 Cyclic voltammetric responses at different temperatures of ferrocene in a 16 17 1 chloroethane tetrahydrofuran 2-methyl-tetrahydrofuran solution containing LiBF4 (0.6 mol dm 3) as supporting electrolyte, (a) Platinum electrode (b) Tl 1223 ( Tl0.sPbo.s Sr2Ca2Cu306). Scan rate 0.025 V s. Potential values are referred to a pseudo-reference silver wire...

Table 2 shows the results of the cyclic voltammetry experiments carried out with benzoquinone solutions. It is seen that the cyclic voltammetric response is also well defined, before and after gamma irradiation. As soon as the electrode is exposed to air, however, important deformations in the cyclic voltammetric peaks are observed (Figs. 1,2). A very well-defined peak of ferrocene was still observed with this electrode, while the cyclic voltammetric peak of benzoquinone vanishes irreversibly. 

Because of the peculiar electrochemical behavior (a single cyclic voltammetric wave characterized by remarkable electrochemical and chemical reversibility), dendrimers terminated with ferrocene-type units can be profitable used as exoreceptors, provided that they contain a group able of interacting through noncovalent bonds with the species to be recognized. Furthermore, such a group has to be located near the ferrocene units to sufficiently perturb their electrochemical response as a consequence of the interaction with the guest species. 

Cyclic voltammetric measurements were made using well-characterized microcrystalline, boron-doped diamond thin-film electrodes to test the material s responsiveness for ferrocene as a function of scan rate, solvent. 

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