Bipyridinium thiols

A cation radical chain cycloaddition-polymerization catalysed by tris(4-bromophenyl)aminium hexachloroantimonate has been reported to afford polymers with an average molecular weight up to 150000. Both cyclobutanation and Diels-Alder polymers were obtained. " The reactivity of the phospine radical cation towards nucleophiles was studied. Tributylphosphine reacted with l,l-dimethyl-4,4-bipyridinium (methyl viologen, MV) in the presence of an alcohol or thiol (RXH X = O, S), which resulted in the gradual formation of the one-electron reduced form... 

Figure 7.4 Electroactive compounds incorporating 4,4 -bipyridinium dications and either one (6) or two (7) thiol groups.

The immersion of a polycrystalline gold electrode into a chloroform/methanol (2 1, v/v) solution of the tetrachloride salt of 6 (Fig. 7.4) results in the adsorption of this electroactive thiol on the metal surface.270 Consistently, the cyclic voltammogram (Fig. 7.5a), recorded after an immersion time of 24 h and extensive rinsing of the electrode surface, shows the reversible reduction of the bipyridinium dications to the corresponding radical cations. In addition, zp increases linearly with v (Fig. 7.6a),... 

Yan and Dong found that -cyclodextrin forms inclusion complexes with linear alka-nethiols in bulk medium and thereby effects solubilization of alkanethiols in the aqueous solution of -cyclodextrin. Such complexes self-assemble on the gold surface to give stable monolayers . 4,4 -Bipyridinium (viologen) containing thiols also form inclusion complexes with cyclodextrins in bulk solution which can be used to prepare self-assembled... 

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