DMSO, cyclic voltammetry

The electrical double-layer structure at Au(l 11), Au(110), Au(100), and Au(210) faces and at a pc-Au electrode has been studied in 5 x 10 3 and 1 x 10-2 M LiC104 solutions in DMSO by cyclic voltammetry and impedance methods.477 The electrodes were cleaned by heating in a flame ... 

To overcome some of the problems associated with aqueous media, non-aqueous systems with cadmium salt and elemental sulfur dissolved in solvents such as DMSO, DMF, and ethylene glycol have been used, following the method of Baranski and Fawcett [48-50], The study of CdS electrodeposition on Hg and Pt electrodes in DMSO solutions using cyclic voltammetry (at stationary electrodes) and pulse polarography (at dropping Hg electrodes) provided evidence that during deposition sulfur is chemisorbed at these electrodes and that formation of at least a monolayer of metal sulfide is probable. Formation of the initial layer of CdS involved reaction of Cd(II) ions with the chemisorbed sulfur or with a pre-existing layer of metal sulfide. 

The redox characteristics, using linear sweep and cyclic voltammetry, of a series of (Z)-6-arylidene-2-phenyl-2,3-dihydrothiazolo[2,3-r][l,2,4]triazol-5(6//)-ones 155 (Figure 24) have been investigated in different dry solvents (acetonitrile, 1,2-dichloroethane, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO)) at platinum and gold electrodes. It was concluded that these compounds lose one electron forming the radical cation, which loses a proton to form the radical. The radical dimerizes to yield the bis-compound which is still electroactive and undergoes further oxidation in one irreversible two-electron process to form the diradical dication on the newly formed C-C bond <2001MI3>. 

Cyclic voltammetry of iron(III) porphyrin-sulfate complexes has been described. Thiosulfate can add to iron(III) porphyrins to give an adduct which is high-spin at normal temperatures but low-spin at low temperatures. The tetraphenylporphyrin adduct undergoes decomposition slowly in DMF to give [Fe (tpp)] plus tetrathionate. In DMSO tetraphenylporphyrinatoiron(III) oxidizes thiosulfate by an autocatalytic process. Tetrathiotungstate complexes of iron(III)-tetra-phenylporphyrin undergo spontaneous reduction to iron(II) products with a half-life of about 30 minutes at ambient temperature. " ... 

An important feature of the rotaxane in Scheme 9.12 is that the translocation of the macrocycle is also achieved by the reduction of the fullerene to its trianion, which is both effected and observed by cyclic voltammetry. In DMSO, the proximity of the macrocycle to the fullerene stabilized substantially the electrogenerated trianion (A i/2 = 46 mV) through n—n interactions. Surprisingly, in THF where the macrocycle is preferentially positioned on the peptide station, a similar behavior was... 

Electrochemistry of [VO(acac)2] in DMSO has been studied by cyclic voltammetry and controlled-potential coulometry at a platinum electrode.516 [VO(acac)2] is irreversibly reduced by one electron at —1.9 V vs. SCE (saturated calomel electrode) to a stable Vm product. In the presence of an excess of ligand, [VO(acac)2] is reduced by two electrons to [V(acac)3] with the V111 species mentioned above and [V(acac)3] as intermediates. The one-electron oxidation of [VO(acac)2] at +0.81 V vs. SCE gives a product. 

Sc(OEP)C>2CMe is 0.4 s, which is the longest for any porphyrin, while the fluorescent yield of 0.2 is very high. The radiative properties are explained in terms of covalent interactions between the metal and the ring as modified by the probable location of the metal ion above the porphyrin plane.24 Scandium OEP complexes are reduced to the a, y-dihydro derivatives on reduction with sodium anthracenide and methanol.25 The redox potentials of Sc(OEP)OH have been determined by cyclic voltammetry to be ligand oxidation in PrCN, 1.03 and 0.70 ligand reduction in DMSO, —1.54 (Ey2 values in V vs. SCE) no metal redox wave was observed.26... 

The role of anthraquinones as mediators of one-electron transfer to molecular oxygen has been studied by cyclic voltammetry in DMSO and DMF solution.217 The reduction potentials of those anthraquinones containing OH groups were substantially shifted towards more positive values in the presence of 02, whereas those without OH groups... 

Two ureido functions introduced into the upper rim of calix[4]arene [52] or the corresponding calix[4]diquinone derivative 41 exhibit good complexa-tion abilities for various anions. Even in highly competitive solvents such as DMSO-d6, quinone 41 shows [53] very strong complexation for H2POj (K4l= 13,900 M-1) or for benzoate (K41=2,430 M-1). The complexation process can be observed using electrochemical methods (cyclic voltammetry) where the addition of anions generates substantial cathodic shifts. 

The receptor 67 [54] shows the sensing of F in DMSO. Upon addition of F to the solution of receptor 67 two bands at 323 and 525 nm decreased and a new band at 652 nm appeared. Furthermore, the color of the solution changed from red-pink to pale purple. These spectral changes were ascribed to the formation of a 1 1 adduct between the metal complex and F anion, in which F anion bound two dipyrrolylquinoxaline units (fC=54,000 M ) Receptor 67 was also studied electrochemically by cyclic voltammetry. A clearly reversible redox signal was observed at 160 mV (vs SHE), which was assigned to the Co(III)/Co(II) reduction. The addition of F led to a complete disappearance... 

Since in good hydrogen bond accepting solvents such as DMSO, the equilibrium content of ends of 2-arylpropionaldehydes is relatively high (up to 50%) [187], their oxidation potentials were readily determined by cyclic voltammetry in at tonitrile/DMSO mixtures [171], A closer analysis, however, indicated that actually enol DMSO complexes were measured exhibiting some enolate character, since the oxidation potentials found proved to be significantly lower than the ones calculated by the above procedure. 

In this Chapter the following common abbreviations are used CV, cyclic voltammetry RDE, rotating disk electrode rds, rate-determining step TBABF4, tetrabutylammonium tetrafluoroborate TBAPF6, tetrabutylammonium hexafluorophosphate TEAP, tetraethylammonium perchlorate TBAP, tetrabutylammonium perchlorate DMSO, dimethyl... 

The stability of phosphaferricinium ions in solution is low cyclic voltammetry reveals that it decreases as the polarity of the medium rises or the degree of ring substitution falls [33]. The parent diphosphaferrocene evolves chemically under electrochemical oxidation in CH2C12, MeCN, and DMSO and is only stable in solvents such as propylene carbonate [33]. Compounds 24 and 25 are reversibly oxidized in dichloromethane but decompose in DMF, probably to the corresponding l,l -biphosphole (Eq. 20) [33] ... 

For the rapid electron transfer process, which follows a reversible chemical step (CE), a procedure is presented for the determination of chemical and electrochemical kinetic parameters. It is based on convolution electrochemistry and was applied for cyclic voltammetry with digital simulation [59] and chronoamperometric curves [60]. The analysis was applied to both simulated and experimental data. As an experimental example, the electroreduction of Cd(II) on HMDE electrode in dimethylsulphoxide (DMSO) [59] and DMF [60] with0.5 M tetraethylammonium perchlorate (TEAP) was investigated. 

A similar response is obtained from the cyclic voltammetry (CV) of [Ru(NH3)5(dmso)]3+ at slow scan rates (<100 mV s-1) (Fig. 3C). However, at higher scan rates, since the scanning rate of CV is faster than the rates of the linkage isomerizations, both complexes display reversible cyclic voltammo-grams for [Ru(NH3)5(dmso)]2+ at 1 V s-1, a couple is observed at 0.97 V, while for [Ru(NH3)5(dmso)]2+ at 20 V s-1, a couple is observed at 0.07 V (Fig. 3B and 3D). This linkage isomerization scheme is illustrated in Fig. 5. 

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