Charge-transfer emission of compact porphyrin-fullerene dyad analyzed by Marcus theory of electron-transfer

Visa Vehmanen, Nikolai V. Tkachenko, Hiroshi Imahori, Shunichi Fukuzumi, Helge Lemmetyinen

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A porphyrin-fullerene dyad, which is characterized by a close proximity of the porphyrin donor and the fullerene acceptor, was found to undergo a photoinduced electron transfer both in solutions and in solid films. Near-infrared charge-transfer (CT) emission was observed and analyzed in frame of the semi-classical Marcus electron-transfer theory yielding values for the reaction free energy, -ΔGo = 1.75 eV, the internal reorganization energy, λv = 0.05 eV, and the donor-acceptor vibrational energy, hvv = 0.14 eV, both in solution and in solid film. The influence of the environment on the CT properties of the dyad is described by a single parameter, the outer-sphere reorganization energy, λs, which varies from 0.05 eV in non-polar solvents and films to 0.13 eV in solvents of moderate polarity. At low temperatures (T < 200 K), the CT emission consists of distinct bands shifted from each other by value hvv. This is the first direct observation of the vibrational frequencies of a porphyrin-fullerene donor-acceptor system.

Original languageEnglish
Pages (from-to)2229-2244
Number of pages16
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Issue number11
StatePublished - 14 Sep 2001

Bibliographical note

Funding Information:
The authors are grateful to Dr Koichi Tamaki for his help in measuring the CT absorption spectrum. This work was supported by the National Programme on Material and Structure Research, Academy of Finland, Grant-in-Aids from Ministry of Education, Science, Sports and Culture, Japan, and the Sumitomo Foundation.


  • Charge-transfer emission
  • Fullerene
  • Marcus electron-transfer theory
  • Porphyrin


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