Voltammetric investigations

Figure 8.13. (a) Cyclic voltammetric investigation of the Ir02/YSZ interface (inset shows the circuit used to model the data)19 and (b) Effect of catalyst-electrode mass on the polarization resistance Rp and the double layer capacitance Cd.19 Scan rate 20 mV/s, T=380°C, pO2=20 kPa. 

An example of the electrolytic cell with an LM used for the voltammetric investigation is... 

Y.H. Wu and S.S. Hu, Voltammetric investigation of cytochrome c on gold coated with a self-assembled glutathione monolayer. Bioelectrochemistry 68, 105-112 (2006). 

Specific recognition of enzymes by their natural substrates and cosubstrates is a common rule but what about recognition of an enzyme by artificial cosubstrate The cyclic voltammetric investigation of glucose oxidase provides an answer to the question.11 Because the flavin prosthetic group... 

Kadish et al. (1989) have described the effect of axially bound anions on the electroreduction of tris(IV) porphyrins in THF. Cyclic voltammetric investigations of zinc tetraphenylporphyrin in dichloromethane in the presence of background electrolyte anions reveal significant perturbations of the met-alloporphyrin s first one-electron oxidation, ranging from 0.86 V for TBAPF6 to 0.50 V for TBAC1 (Seely et al., 1994). 

To adapt this fundamental relationship to the case of voltammetric investigations on redox processes of metal complexes, let us assume that the reversible reduction of any complex ... 

Arylindenes undergo sigmatropic 1,5-shifts, induced oxidatively [267], thermally [268], photochemically [269], and re-ductively [270]. The reductive rearrangement of 1,1,3-triphenylindene, yielding the dianion of l,2,3-triphenyl-2H-indene, has been the subject of voltammetric investigations in DMF-TBAP [271]. The reaction follows an EEC or EDisp C pathway. 

Beck 23,37,38) carried out voltammetric investigations of chelates in solution (phthalocyanine and tetra-aza-annulene in 85—90% H2SO4). The particularly active electrocatalysts (FePc and CoTAA) showed very positive redox potentials and a pronounced positivization of the polarographic oxygen step in 85 % sulfuric acid. On the basis of these results, Beck proposed the following mechanism... 

Various complexes of the type [M (M04 S )]2- (M = Fe, Co, Ni, Pd) and also [(FeCl2)2-MoS4]2- can be reduced reversibly in a one-electron process (equation 9) and some also in a second one-electron process (equation 10) according to cyclic voltammetric investigations. 

Raspor, B., Nurnberg, H.W., Valenta, P. and Branica, M., 1984. Studies in seawater and lakewater on interactions of trace metals with humic substances isolated from marine and estuarine sediments. 11. Voltammetric investigations on trace metal complex formation in the dissolved phase. Mar. Chem., 15 231-249. 

Although an early voltammetric investigation demonstrated that dioxygen in aqueous solutions is reduced to hydrogen peroxide at passivated platinum electrodes,18... 

The low solubility and apparent decomposition of the dithiolotrithiole (23) in solution prohibited voltammetric investigation of its structure <8lJOC775>. 

Fremy s salt, 0N(S03)22 is the last of the stable free radicals in aqueous solution to be described in this review. Quantitative studies of its chemistry are rare, and the reader is referred to a recent paper by Balasubramanian and Gould for details (26). According to these workers the protonated radical has a pK less than 5.6. They cite a potential of —0.350 V for the 0N(S03)2270N(S03)23 couple in alkaline media. This potential was derived from potentiometric titrations of this electrochemically reversible couple by Aoyagui and Kato, who also noted that for H0N(S03)22 the pKt = 12.0 (20). These results have been confirmed in a voltammetric investigation (255). 

Asymmetric functionalization was achieved in the two dendrimers 60 and 61, which contain two branches terminated with electron-donor TTF units and one branch terminated with electron-acceptor anthraquinone (AQ) units [131]. Cyclic voltammetric investigation in acetonitrile showed that each of these electroactive units are noninteracting, giving rise to two waves on oxidation (due to TTF) and to two waves on reduction (due to AQ). The number of electrons exchanged in each of... 

Polarographic and voltammetric investigations [20-22] of the behavior of tert-huXyX iodide and tert-huiy bromide have revealed that, depending on the solvent and supporting electrolyte, the iodide undergoes stepwise reduction and the bromide exhibits either a single two-electron reduction or a pair of one-electron reductions. 

The cyclic voltammetric investigations of MeHSiCb and PhHSiCb showed, in accordance to the results of non-hydrogenated silanes, a higher reduction potential for the methylated derivative than for the phenylated one [3], In both cases the reduction is quasi-reversible, hence, with increasing potential sweep, the reduction waves shift to more negative values. 

A systematic voltammetric investigation of the redox potentials of 23 different metal complexes of OEP including all members of the first transition series (Table 7) has yielded some electrochemical regularities [.Fuhrhop (74), Kadish (109)] ... 

In order to determine the kinetic parameters of the reaction corrected from diffusion phenomenon, a voltammetric investigation was pursued with a rotating platinum ring disk electrode. Figure 21.10 represents current density-potential curves obtained for different rotation speeds and for the positive variations of potential. It appears that the current density of the rotating disk increases with the rotation rate. 

The cyclic voltammetric investigation of the bis[2.2]paracyclophane 24 showed that up to four electrons can be introduced into this molecule. The... 

---