Pagona Georgia, Sandanayaka Atula S D, Araki Yasuyuki, Fan Jing, Tagmatarchis Nikos, Yudasaka Masako, Iijima Sumio, Ito Osamu
J Phys Chem B. 2006 Oct 26;110(42):20729-32. doi: 10.1021/jp064685m.
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.
四价阳离子水溶性卟啉（H(2)P(4+)）通过π-π堆积相互作用固定在碳纳米角（CNH）的骨架上，而不破坏其π电子网络。通过电子显微镜和光谱技术对CNH-H(2)P(4+)纳米聚集体的稳定水溶液进行了研究。通过稳态以及时间分辨荧光发射光谱探测了CNH-H(2)P(4+)纳米聚集体中H(2)P(4+)部分的有效荧光猝灭，这表明从光激发的H(2)P(4+)到CNH发生了电荷分离。在甲基紫精二价阳离子（MV(2+)）和空穴陷阱存在的情况下，通过对CNH-H(2)P(4+)进行光照射，观察到甲基紫精还原物种的积累，这表明从最初形成的电荷分离态发生了电子迁移。瞬态吸收光谱对瞬态物种如电荷分离态（CNH(-))-(H(2)P(4+))(+)有了进一步的了解，该电荷分离态在MV(2+)和空穴转移剂存在时被消耗，留下还原的甲基紫精。
