An electrochemical device for switching fluorescence with electronic and chemical signals

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The reduced form of azines is non-fluorescent, whereas their oxidized form is strongly fluorescent. When the redox-active dye was incorporated into the polyelectrolyte film Nafion【○!R】 or electropolymerized on glassy carbon, thus, the dye-modified electrodes in acidic solutions fulfiled the requirements for the design of a bistable electro-photoswitch. The dye-loaded film electrode can operate as a dual-mode switching device when the electronic input signal is coupled with the acid-base reaction of the dye molecule. Its second protonation lowered the fluorescence strength greatly because the fully protonated oxidized-form was non-fluorescent ; however, the corresponding pK was too low to change the pH of the electrolyte solution rapidly.The addition of 1,1'-ferrocenedimethal to the solution quenched the fluorescence of the oxidized form efficiently to switch off the fluorescence. The gust molecule incorporated into the film formed a nonfluorescent complex with the cationic dye, thereby deactivating it electrochemically. Although there remains a question about the response speed for application to an electronic/photonic device, the modified electrode has another immediate use as a selective electrofluorometric 1,1'-ferrocenedimethal sensor.Polyazine films electrocatalized the direct oxidation of reduced β-nicotinamide adenine dinucleotide and dopamine. The binding interaction decreased with protonation of the polymer. Its mediating properties can arise from the coupled electron and proton transport in the electroactive nitrogen-including polymers. Thus, one requires examining electron exchange between the catalytic center and solution substrate : the electron exchange can depend on both the reduction and protonation levels of the polymer.