Supramolecular triad and pentad composed of zinc-porphyrin(s), oxoporphyrinogen, and fullerene(s): Design and electron-transfer studies

Amy Lea Schumacher, Atula S.D. Sandanayaka, Jonathan P. Hill, Katsuhiko Ariga, Paul A. Karr, Yasuyuki Araki, Osamu Ito, Francis D'Souza

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

By adopting a "covalent-co-ordinate" bonding approach, novel supramolecular pentad and triad molecules composed of zinc-porphyrin(s), fullerene(s), and oxoporphyrinogen redox-/photoactive entities have been constructed, and also characterized by means of spectral and electrochemical techniques. The geometry and electronic structures of the pentad and the triad were deduced by means of DFT calculations. Free-energy calculations suggested that the photoinduced electron/energy transfer from the zinc-porphyrin (ZnP) singlet-excited state to the imidazole modified fullerene (ImC60) acceptor and oxoporphyrinogen (OxP) entities is feasible for both the triad and the pentad. The charge-separation rates (kCS) determined from picosecond time-resolved emission studies were higher for pentad (C 60Im:ZnP)2-OxP than for the corresponding triad. C 6()Im:ZnP-OxP. A comparison of the kCS values previously reported for the covalently linked bis-(zinc-porphyrin)-oxoporphyrinogen triad suggests that employing a fullerene acceptor improves the electron-transfer rates. Nanosecond transient absorption studies provide evidence for the occurrence of electron-transfer processes. Lifetimes of the radical ion pairs (τRIP) are in the range of hundreds of nanoseconds, which indicates that there is charge stabilization in the supramolecular systems.

Original languageEnglish
Pages (from-to)4628-4635
Number of pages8
JournalChemistry - A European Journal
Volume13
Issue number16
DOIs
Publication statusPublished - 2007 Jun 21

Keywords

  • Density functional calculations
  • Electron transfer
  • Fullerenes
  • Porphyrinoids supramolecular chemistry

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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