Viologens, uses

Electrochemical oxidation of X produces a polymer film with polythiophene as the backbone and viologen centers as pendant redox groups. The electrochemical properties of the polymer are the combination of polythiophene and viologen. Using viologen subunits as the internal standard (one per repeat unit of the polymer), the "doping level" of the oxidized polythiophene backbone at its maximum conductivity can be measured and is about 25%. The charge transport via the pendant V2+/+ of poly(l) has been studied by... 

All routes used toxic substances such as methanol, acetic acid (D), oxalic acid ethyl ester (A-D), cyclohexane (A), toluene, sulfuric acid and hydrochloric acid. Overall, no major differences were observed with the exception of viologen used in A This substance is toxic to fish, meaning that the sewage of A has to be processed in a water treatment plant, which is not necessary in B. 

T. Endo, Y. Saotome and M. Okamura, Viologen used in electron phase transfer . 

Evans and coworkers have published an interesting study of the electrochemical behavior of a ferrocene-carboxylic acid derivative in the presence of BCD [18] and a summary of general guidelines on the electrochemical methodology that can be used to assess the complexation of redox-active molecules by cyclodextrin hosts [19]. However, the amphiphilic character of the surfactant viologens used in this work prevented us from applying most of these methods because the voltammetric... 

Donor/acceptor association and the electron-transfer paradigm form the unifying theme for the C—C bond cleavage of various benzpinacols and diary-lethane-like donors in the presence of different electron acceptors (such as chloranil (CA), dichlorodicyanobenzoquinone (DDQ), tetracyanobenzene (TCNB), triphenylpyrylium (TPP+), methyl viologen, nitrosonium cation, etc.). Scheme 13 reminds us how this is achieved by either CT photolysis of the D/A pair or via diffusional quenching of the excited electron acceptor A by the electron donor D. 

Sometimes electron transfer via the transport of electron carrier and via electron exchange reactions occur simultaneously. Co-existence of both these channels was observed for dark electron transfer across the viologen-containing vesicle membrane [169, 201]. To illustrate this let us turn back to the experiments shown schematically in Fig. 5 a. In accordance with the reaction sequence (34)-(37) and... 

The formation of inclusion complexes and intertwined molecules, like the cate-nanes and rotaxanes discussed in Chapter 12, is the point of interest in most electrochemical investigations of CyDs in solution [23]. The internal hydrophobicity of the cavity with the hydrophilic bases of CyD allows us to increase the solubility of aromatic electroactive guests as shown for example in the use of azobenzene [24], ferrocene [25-28], or viologen [29], so that their electrochemistry can be carried out in an aqueous medium. 

Data obtained in presence of methyl viologen and methyl pyridinium are compared with different divalent and monovalent metal cations and allow us to calculate their binding constants (assuming that the difference is only due to binding). 

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