Analytical Sciences

Evidences of Electron Transfer of a Fullerene Anion Radical (C₆₀^•�|) Prepared under Visible-Light Illumination at a Nitrobenzene/Water Interface

Shigeru WATARIGUCHI,* Masaaki FUJIMORI,** Kosuke ATSUMI,** and Teruo HINOUE**

*Interdisciplinary Graduate School of Science and Technology, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
**Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan

Fullerene (C₆₀) changes to its anion radical (C₆₀^•−) in the presence of tetraphenylborate (TPB⁻) under visible-light illumination. Using voltammetry at a liquid/liquid interface, we investigated the electron transfer (ET) between C₆₀^•−, previously prepared based on this photochemical reaction, in a nitrobenzene (NB) solution and hexacyanoferrate(III) ([Fe(CN)₆]³⁻) or proton in an aqueous solution. We suggest that positive currents appearing in voltammograms are due to the ion transfer of decomposition products of TPB⁻ and ET from C₆₀^•− in the NB phase to [Fe(CN)₆]³⁻, or proton in the W phase. ¹¹B NMR revealed that TPB⁻ decomposed to some borate anions during the photochemical reaction of fullerene. Furthermore, when the NB solution containing C₆₀^•− was mixed with an aqueous solution containing [Fe(CN)₆]³⁻ or proton, absorption bands of C₆₀^•− in a visible/near infrared absorption spectrum disappeared. This disappearance supports the ET across the NB/W interface. This finding is significant as both an example of ET at a liquid/liquid interface including photochemical reactions and the photochemistry of C₆₀.

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