Zinc Porphyrins Covalently Bound to the Side Walls of Single-Walled Carbon Nanotubes via Flexible Bonds: Photoinduced Electron Transfer in Polar Solvent

Single-walled carbon nanotubes (SWCNTs) tethering zinc porphyrins (ZnP) with flexible aliphatic bonds, ZnP-(spacer)-SWCNT, were prepared with applying the Prato reaction. Under illumination by visible light (>500 nm), ZnP- (spacer)-SWCNT effectively catalyzed the reduction of the benzylviologen dication (BV(2+)) by 1-benzyl-1,4-dihydronicotinamide in dimethylformamide (DMF). The H(2) evolution was also confirmed when the ZnP- (spacer) -SWCNT aqueous solution was illuminated by visible light in the presence of Pt particles. Furthermore, the photocurrent and photovoltage were observed to respond to the on-off cycles of the visible light irradiation in a solar cell consisting of a transparent glass electrode modified with ZnP- (spacer) -SWCNT. The time-resolved fluorescence and absorption spectral measurements revealed the photoinduced electron-transfer mechanism.