An electrochemical device for switching fluorescence with electronic and chemical signals

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15550116
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Functional materials chemistry
• Research Institution: Kanazawa University
• Principal Investigator: KOMURA Akitoshi Kanazawa University, Natural Science Departmen, Professor, 自然科学研究科, 教授 (00019746)
• Co-Investigator(Kenkyū-buntansha): YAMAGUCHI Takahiro Kanazawa University, Natural Science Departmen, Lecturer, 自然科学研究科, 講師 (90272947)
• Project Period (FY): 2003 – 2005
• Keywords: Azines / Fluorescence / Oxidation-reduction / Quenching / Chemically modified electrodes / Supramolecular systems / Electrochemical switching

Research Abstract

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.