Supramolecular triads bearing porphyrin and fullerene via 'two-point' binding involving coordination and hydrogen bonding

Francis D'Souza, Mohamed E. El-Khouly, Suresh Gadde, Melvin E. Zandler, Amy Lea McCarty, Yasuyaki Araki, Osamu Ito

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

Supramolecular triads composed of fullerene (C60) as primary electron acceptor, zinc porphyrin (ZnP) as primary electron donor, and either a ferrocene (Fc), or N,N-dimethylaminophenyl (DMA), or N,N-diphenylaminophenyl (DPA) entity as a second electron donor were constructed via a 'two-point' binding motif involving axial coordination and hydrogen bonding. The B3LYP/3-21G(*) optimized structures revealed disposition of the three entities of the triads in a triangular fashion. The redox behavior of the different components was studied using cyclic voltammetry in o-dichlorobenzene containing 0.1 M (n-C4H9)4NClO4. The oxidation potentials of the second electron donor followed the trend: Fc<DMA<DPA, and the free-energy calculations suggested the possibility of the occurrence of sequential hole transfer in these triads. Efficient electron transfer from the excited singlet state of zinc porphyrin to the fullerene entity was observed in all of the studied triads in o-dichlorobenzene. Longer charge-separated states were observed for zinc porphyrin with a carboxylic acid compared with that having an amide group. The ratios of the experimentally determined forward to reverse electron transfer rates, kCS/k CR were evaluated to be 103 for triads formed by zinc porphyrin with a carboxylic acid, suggesting charge stabilization in these triads.

Original languageEnglish
Pages (from-to)1967-1978
Number of pages12
JournalTetrahedron
Volume62
Issue number9
DOIs
Publication statusPublished - 2006 Feb 27

Keywords

  • Charge recombination
  • Fullerene
  • Photoinduced charge-separation
  • Supramolecular triads
  • Supramolecule
  • Zinc porphyrin

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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