Viologen monocation radical

Figure 11.17 illustrates a representative process for the catalytic conversion of hydrogen ions to hydrogen gas. It begins (A, Fignre II.I7) with excitation of the photosensitizer [Ru(bpy)3] to afford [Ru(bpy)3], which is quenched by the dicationic electron mediator methyl viologen in step C to afford a monocation radical. The electron from... 

When dimethyl viologen dication is entrapped in DPPC vesicles and irradiated in the presence of external K4[Fe(CN)g], the viologen is reduced to the radical monocation and iron is oxidized. Light-induced membrane potential is thus built up (Calvin, 1978). Electrons can be stored and released in viologen-benzoquinone polymers on electrode surfaces. At first the quinone is reduced to the hydroquinone at low pH. Two electrons are entrapped per hydroquinone monomer. Upon raising the pH to 6-9, the viologen becomes reduced by the hydroquinone anions and delivers the electrons to the electrode (Smith et al., 1989)... 

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