Tuning reductive and oxidative photoinduced electron transfer in amide-linked anthraquinone-porphyrin-ferrocene architectures

Jascha Melomedov, Julian Robert Ochsmann, Michael Meister, Frederic Laquai, Katja Heinze*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Porphyrin amino acids 3a-3h with meso substituents Ar of tunable electron-donating power (Ar = 4-C6H4OnBu, 4-C 6H4OMe, 4-C6H4Me, Mes, C 6H5, 4-C6H4F, 4-C6H 4CF3, C6F5) have been linked at the N terminus to anthraquinone Q as electron acceptor through amide bonds to give Q-PAr dyads 4a-4h. These were conjugated to ferrocene Fc at the C terminus as electron donor to give the acceptor-chromophore-donor Q-P Ar-Fc triads 6a-6h. To further modify the energies of the electronically excited and charge-separated states, the triads 6a-6h were metallated with zinc(II) to give the corresponding Q-(Zn)PAr-Fc triads Zn-6a-Zn-6h. The Q-PAr1 dyad (Ar1 = C 6H5) was further extended with a second porphyrin P Ar2 (Ar2 = 4-C6H4Me) as well as appended to a ferrocene to give the tetrad Q-PAr1-PAr2-Fc 9. Almost all the conjugates show strongly reduced fluorescence quantum yields and excited-state lifetimes, which has been interpreted as photoinduced electron transfer (PET) either from the excited porphyrin to the quinone (oxidative PET) or from the ferrocene to the excited porphyrin (reductive PET). Electrochemical data, absorption spectroscopy, steady-state emission, time-resolved fluorescence, transient absorption pump-probe spectroscopy as well as DFT calculations have been used to elaborate the preferred PET pathway (reductive vs. oxidative PET) in these architectures with systematically varied electron-donating substituents at the central chromophore.

Original languageEnglish (US)
Pages (from-to)1984-2001
Number of pages18
JournalEuropean Journal of Inorganic Chemistry
Issue number11
DOIs
StatePublished - Jan 1 2014

Keywords

  • Density functional calculations
  • Electron transfer
  • Porphyrinoids
  • Quinones
  • Substituent effects

ASJC Scopus subject areas

  • Inorganic Chemistry

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