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

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.