Electrochemical synthesis cyclic voltammetry

Shinohara et al.52n suggested that the diffusion rate of dopant ions in polypyrrole films depends upon the size of the anion used as counter-ion in the electrochemical synthesis so that films prepared with CI counter-ions were impermeable to larger ions, at least in the time-scale of a cyclic voltammetry experiment. Tietje-Girault et al. 522) made two-layer polypyrrole films in which a layer was prepared with a large... 

Electric arcs, in metal vapor synthesis, 1, 224 Electric-field-induced second harmonic generation Group 8 metallocenes, 12, 109 for hyperpolarizability measurement, 12, 107 Electrochemical cell assembly, in cyclic voltammetry, 1, 283 Electrochemical irreversibility, in cyclic voltammetry, 1, 282 Electrochemical oxidation, arene chromium carbonyls, 5, 258 Electrochemical properties, polyferrocenylsilanes, 12, 332 Electrochemical reduction, bis-Cp Zr(III) and (IV) compounds, 4, 745 Electrochemical sensors biomolecule—ferrocene conjugates... 

The stable did -azulcnyl)thieno[3,2-9]thiophene-2,5-diyl spacers 78a and 78b were prepared by hydride abstraction of the corresponding 2,5-bis[bis(methyl and 3,6-di-tert-butyl-l-azulenyl)methyl]thieno[3,2-9]thiophenes 77a and 77b, the synthesis of which was established by the reaction of 1-methyl- and 1,6-di-t-butylazulcncs 75a and 75b with thicno 3,2-9 thiophene-2,5-dicarbaldehyde 76 (Scheme 11). The dications 76 showed high stability with large pA"R+ values. The electrochemical behavior of 78 was examined by cyclic voltammetry (CV). Chemical reduction of 78 with Zn powder in acetonitrile afforded 79 as deep-colored crystals, which exhibited rather high... 

Apparatus and materials. All electrochemical polymerizations, amperometric measurements and cyclic voltammetry were carried out with an EG G Princeton Applied Research Potentiostat model 273. Pyrrole was purified by vacuum distillation and by passage over neutral alumina prior to electropolymerization. The polyanions (1) used as dopants are shown in Figure 1, and were purified twice by precipitation from methanol in 0.1 M HC1. Detailed information about their synthesis and catalytic... 

Several TTF-crown ether derivatives, such as LI, have been prepared and investigated as potential metal ion sensor systems [180]. Cyclic voltammetry studies revealed in all cases two one-electron reversible oxidation steps with Ei/2( ) = 0.48 and E]/2(i) = 0.64 V (vs. SCE), respectively. The addition of controlled amounts of metal ions such as Li", Na", K", and Ag leads to shifts of Ei/2H) up to 80 mV toward more anodic potentials, as expected for a repulsive coulombic interaction. The magnitudes of the observed shifts are dependent on the hole size in the crown ether and on the concentration of the metal ion, up to a certain limit. The synthesis and spectroscopic and electrochemical studies of unsym-metrical annelated TTF-crown ethers bound to Na, Ag", and Ba " have been recently described [181]. 

One line in bioelectrochemistry is rooted in electrochemical techniques, spectroscopy, and other physical chemical techniques. Linear and cyclic voltammetry are central.Other electrochemical techniques include impedance and electroreflectance spectroscopy," ultramicro-electrodes, and chronoamperometry. To this come spectroscopic techniques such as infiared, surface enhanced Raman and resonance Raman,second harmonic generation, surface Plasmon, and X-ray photoelectron spectroscopy. A second line has been to combine state-of-the-art physical electrochemistry with corresponding state-of-the-art microbiology and chemical S5mthesis. The former relates to the use of a wide range of designed mutant proteins, " the latter to chemical synthesis or de novo designed synthetic redox metalloproteins. " " ... 

Another route for the preparation of composites based on PANI and SWNTs is electrochemical synthesis [26,30,144]. A common method for the electrochemical polymerization of aniline is cychc voltammetry. The aqueous acidic medium frequently used is HCl or H2SO4. It is well known that cyclic voltammograms of polyaniUne recorded in aqueous acidic media usually show two redox couples associated with the inteconversion between leucoemeraldine and emeraldine (first couple) and between emeraldine and pernigraniline (the second couple) [ 151 ]. At the potential of the second oxidation peak, PANI is unstable in... 

In order to immobilize enzymes in conducting polymers to fabricate biosensors, the electrochemical synthesis of polypyrrole films was studied under different conditions. It was found that the size and morphology of polypyrrole films synthesized using cyclic voltammetry were affected by the concentration of the supporting electrolyte at a scan potential range between 0.0 and 1.0 V (vs. SCE), and at a scan rate of 48 mV s [47]. The diameters of particles prepared in a solution containing 0.10 M pyrrole and 0.10 M NaCl... 

The fabrication of polypyrrole wires via electropolymerization within poly(methyl methacrylate) nanochannels on an indium tin oxide (ITO) substrate was reported by Chen et al. [53]. The electrochemical synthesis of polypyrrole was performed by a cyclic voltammetry method in aqueous 0.1 M NaC104 containing 0.1 M pyrrole monomer. The potential was scanned 10 times between -0.7 and +0.6 V vs. Pt at a scan rate of 100 mV s . The nanochannels act as templates for electropolymerization of polypyrrole nanowires. 

Electrochemical oxidation and reduction of polyanilines has been extensively studiedlO,23,24 by cyclic voltammetry techniques, usually in aqueous acid solutiorv using either electrochemically synthesized polyaniline films/ or chemically synthesized powders. This is a convenient method for the electrochemical doping of extremely small amounts of leu-coemeraldine but it is not well suited for the synthesis of large quantities of oxidatively doped polymer in a known oxidation state. 

Not all workers, however, are convinced of the validity of the accepted mechanisms for these types of reactions. Tan et al have studied a phase transfer catalysed Williamson ether synthesis by electrochemical methods including cyclic voltammetry [23], and came to the conclusion that... 

Catalano and coworkers reported the synthesis and brief electrochemical characterization of [PtMe2Br(bpy-Fc2)CH2-]nR (R = substituted phenyl groups) [79]. In TBAH/AN solution, these dendrimers exhibited a single redox wave centered at -F0.50 V versus Ag/AgCl corresponding to the Fc/Fc+ redox reaction. Diffusion coefficients were also determined by a combination of chronocoulometry and cyclic voltammetry using a microelectrode and were found to be 1.1 to 1.7 x 10 cm s in DMF/TBAP solution. 

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