title: Electronic interplay on illuminated aqueous carbon nanohorn-porphyrin ensembles.
abstract: Tetracationic water-soluble porphyrin (H(2)P(4+)) has been immobilized by pi-pi stacking interactions onto the skeleton of carbon nanohorns (CNH), without disrupting their pi-electronic network. The stable aqueous solution of the CNH-H(2)P(4+) nanoensemble was examined by both electron microscopy and spectroscopic techniques. The efficient fluorescence quenching of the H(2)P(4+) moiety in the CNH-H(2)P(4+) nanoensemble was probed by steady-state as well as time-resolved fluorescence emission spectroscopy, suggesting charge separation from the photoexcited H(2)P(4+) to CNH. In the presence of methyl viologen dication (MV(2+)) and a hole trap, accumulation of the reduced species of methyl viologen was observed by the photoillumination of CNH-H(2)P(4+), suggesting that the electron migration from the initially formed charge-separated state takes place. Transient absorption spectroscopy gave further insights on the transient species such as the charge-separated state (CNH(*-))-(H(2)P(4+))(*+), which was consumed in the presence of MV(2+) and hole shifter, leaving the reduced methyl viologen.
authors.forename: Georgia
authors.initials: G
authors.lastname: Pagona
authors.forename: Atula S D
authors.initials: AS
authors.lastname: Sandanayaka
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Araki
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
authors.forename: Nikos
authors.initials: N
authors.lastname: Tagmatarchis
authors.forename: Masako
authors.initials: M
authors.lastname: Yudasaka
authors.forename: Sumio
authors.initials: S
authors.lastname: Iijima
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito