Long-Lived Photoinduced Charge Separation in Inclusion Complexes Composed of a Phenothiazine-Bridged Cyclic Porphyrin Dimer and Fullerenes

Takuya Kamimura, Kei Ohkubo, Yuki Kawashima, Shuwa Ozako, Ken Ichi Sakaguchi, Shunichi Fukuzumi, Fumito Tani

研究成果: Contribution to journalArticle査読

23 被引用数 (Scopus)


C60, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), lithium-cation-encapsulated C60 (Li+@C60), and [6,6]-diphenyl-C62-bis(butyric acid methyl ester) (bis-PCBM) were included into a phenothiazine-bridged cyclic free-base porphyrin dimer (H4-Ptz-CPDPy(TEO)) in a polar solvent (benzonitrile) with large association constants of 1.3 × 106, 6.4 × 105, 3.2 × 106, and 2.5 × 105 M-1, respectively. Based on the electrochemical data, the lowest energy levels of the charge-separated (CS) states for the inclusion complexes of H4-Ptz-CPDPy(TEO) with C60, PCBM, Li+@C60, and bis-PCBM (designated as C60⊂H4-Ptz-CPDPy(TEO), PCBM⊂H4-Ptz-CPDPy(TEO), Li+@C60⊂H4-Ptz-CPDPy(TEO), and bis-PCBM⊂H4-Ptz-CPDPy(TEO)) composed of the phenothiazine donor and fullerene acceptors were determined to be 1.30, 1.40, 0.66, and 1.51 eV, respectively. Both C60⊂H4-Ptz-CPDPy(TEO) and PCBM⊂H4-Ptz-CPDPy(TEO) underwent electron transfer upon photoexcitation of the porphyrin and fullerene chromophores, and the resultant photoinduced CS states comprised the phenothiazine cation and the fullerene anions with lifetimes of 0.71 ms determined by time-resolved transient absorption spectra. Li+@C60⊂H4-Ptz-CPDPy(TEO) also afforded a similar CS state with a lifetime of 0.56 ms. These lifetimes are the longest values ever reported for the CS states of phenothiazine-fullerene complexes in solution. The spin states of these long-lived CS states were assigned to be triplet by ESR spectroscopy. The remarkably long CS lifetimes are attributable mainly to the lower CS energies than the triplet energies of the phenothiazine, fullerenes, and porphyrin moieties and the spin-forbidden slow back-electron-transfer processes. On the other hand, the photoinduced CS state of bis-PCBM⊂H4-Ptz-CPDPy(TEO) was quenched rapidly by fast back electron transfer due to the relatively high CS energy comparable to the triplet energies of the porphyrin and fullerene.

ジャーナルJournal of Physical Chemistry C
出版ステータス出版済み - 10 23 2015

All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜


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