Excitation-wavelength-dependent, ultrafast photoinduced electron transfer in bisferrocene/BF2-chelated-azadipyrromethene/fullerene tetrads

Venugopal Bandi, Mohamed E. El-Khouly, Kei Ohkubo, Vladimir N. Nesterov, Melvin E. Zandler, Shunichi Fukuzumi, Francis D'Souza

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

Donor-acceptor distance, orientation, and photoexcitation wavelength are key factors in governing the efficiency and mechanism of electron-transfer reactions both in natural and synthetic systems. Although distance and orientation effects have been successfully demonstrated in simple donor-acceptor dyads, revealing excitation-wavelength-dependent photochemical properties demands multimodular, photosynthetic-reaction-center model compounds. Here, we successfully demonstrate donor- acceptor excitation-wavelength-dependent, ultrafast charge separation and charge recombination in newly synthesized, novel tetrads featuring bisferrocene, BF2-chelated azadipyrromethene, and fullerene entities. The tetrads synthesized using multistep synthetic procedure revealed characteristic optical, redox, and photo reactivities of the individual components and featured "closely" and "distantly" positioned donor-acceptor systems. The near-IR-emitting BF2-chelated azadipyrromethene acted as a photosensitizing electron acceptor along with fullerene, while the ferrocene entities acted as electron donors. Both tetrads revealed excitation-wavelength-dependent, photoinduced, electron-transfer events as probed by femtosecond transient absorption spectroscopy. That is, formation of the Fc+-ADP-C60.- charge-separated state upon C60 excitation, and Fc+-ADP.--C 60 formation upon ADP excitation is demonstrated.

Original languageEnglish
Pages (from-to)7221-7230
Number of pages10
JournalChemistry - A European Journal
Volume19
Issue number22
DOIs
StatePublished - 27 May 2013

Keywords

  • X-ray analysis
  • artificial photosynthesis
  • electron transfer
  • fullerenes
  • photochemistry

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