First anodic electrochemical

For anodic processes there are also two wave steps on the polarisation curves at potentials cpi and 92 corresponding to two electrochemical reactions. The first anodic electrochemical reaction for sulphide at the potential (pi corresponds to its anodic decomposition (transition of ions of metals in solution),... 

These processes represent the first anodic electrochemical reaction (FAER), which can he expressed hy the following overall equation ... 

Parent (unsubstituted) PF was first synthesized electrochemically by anodic oxidation of fluorene in 1985 [266] and electrochemical polymerization of various 9-substituted fluorenes was studied in detail later [220,267]. Cyclic voltammogram of fluorene ( r1ed= 1.33 V, Eox = 1.75 V vs. Ag/Ag+ in acetonitrile [267]) with repetitive scanning between 0 and 1.35 V showed the growth of electroactive PF film on the electrode with an onset of the p-doping process at 0.5 V (vs. Ag/Ag+). The unsubstituted PF was an insoluble and infusible material and was only studied as a possible material for modification of electrochemical electrodes. For this reason, it is of little interest for electronic or optical applications, limiting the discussion below to the chemically prepared 9-substituted PFs. 

When a typical active material is employed as the anode, a number of additional species generated on the electrode surface must also be considered. They can influence the process performance, causing additional chemical reactions on the electrode surface if the redox couple remains at the surface (i.e., Pt/PtO), or in the bulk solution if the electrogenerated species are dissolved (i.e., A1/A13+). A scheme outlining the processes that need to be considered in the anodic electrochemical zone is shown in Fig. 4.3. The first process to be taken into account is the formation of oxidized species on the electrode surface. These species can either remain on the surface or move toward the bulk zone. In the latter case, mass transfer to the bulk zone and possible chemical reactions in this zone must be considered. 

Another similarity between Cgo and C70 is their anodic electrochemical behavior. Of the solvents used thus far, the only one in which C70 undergoes a quasireversible oxidation process is in TCE [17]. Within the potential window of this solvent, two oxidation waves are observed by OSWV at + 1.20 and + 1.75 mV (see Fig. 4). The former is 60 mV more negative than the corresponding first oxidation potential of Cgo- Thus C70 is easier to oxidize than 50, a not surprising fact taking into account the lower ionization potential of C70 in the gas phase (7.3 eV) [13]. The second oxidation, which occurs at the limit of the... 

In 1862, Letheby [30] discussed the production of a blue substance by the electrolysis of sulfate of aniline, nowadays considered as the first reported electrochemical synthesis of a conjugated polymer, in his case poly(aniline). Since then a great number of different monomers were synthesized that form conducting polymers. The synthesis method of choice for preparing these polymers involves the anodic oxidation of a suitable monomer M into a cation radical... 

Electrochemical reduction of [CP-p and the fraction of CP not oxidized in the first anodic step at a fixed value of cathodic potential E, i.e. 

The selective electrochemical oxidation of one reaction partner gave rise to the first anodic phenol-arene cross-coupling (Scheme 4) [4]. The presence of additional water or methanol in the electrolyte turned out to be beneficial for the yield as well as selectivity [18]. In many cases, the ratio for the mixed biaryl (AB) vs. biphenyl (BB) exceeded 100 1. Since no leaving functionalities are required, simple starting materials can be employed, and the 1,1,1,3,3,3-hexafluoroisopropanol is almost quantitatively recovered. Biaryls 8-10 with different substitution patterns are feasible in good isolated yields. The transformation is compatible with a variety of functional groups and tolerates sulfide and tertiary alkyl moieties in the substrates. Compound 11 and 12 were the only observed mixed biaryls in the reaction mixture. Products originating... 

Polythiophene has been prepared first by electrochemical polymerization. Since a film is produced on the anode during polymerization, this method is suitable for the preparation of polymers such as polythiophene and poly(3-methylthiophene), which is not processable after polymers are formed. However, in electrochemical polymerization, the yield of polymers is low and the polymers often do not have a well-... 

Anodic Electrochemical Oxidation. The anodic electropolymerization of thiophene presents several distinct advantages such as the absence of catalyst, direct grafting of the doped conducting polymer onto the electrode surface (which is of particular interest for electrochemical applications), easy control of the film thickness by deposition charge, and possibility to perform a first in situ characterization of the growing process or of the polymer by electrochemical and/or spectroscopic techniques. 

Figure 7.34. (a) Voltammograms (first and second scan) recorded for film (approx. 22 nmol on approx. 1 cm Pt flag electrode) in 0.1 M TBAPFe solution after the electrochemical reduction and reoxidation of the film in 0.05 M Cd(bpy)3(Pp6)2 solution (see text). First scan, solid line second scan, broken line. Scan rate, 50 mV/s. 5=500 / A except for the portion of the first anodic scan between —0.1 V and -H 2.0 V, for which S was 20 /xA in order to detect any metallic Cd oxidation, (b) Voltammogram recorded for 1.7 mM Cd(bpy)3(Pp6)2 in 0.1 M TBAPp6 using the same electrode as in (a). Scan rate, 50 mV/s S = 500 fiA. Solid and broken lines represent scans performed in differential potential ranges. 

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