First Example of Ultrafast Photoisomerisation-Like Photophysics for Tetrapyrrol Systems: Ethylene-Bridged Porphyrin Dimers

  • V. S. Chirvony
  • M. Chachisvilis
  • A. M. Shulga
  • B. Källebring
  • S. Larsson
  • V. Sundström
Conference paper
Part of the Springer Series in Chemical Physics book series (CHEMICAL, volume 62)

Abstract

It is commonly accepted that porphyrin molecules are sufficiently rigid structures having relatively large (~15500 cm-1) ∆E(S1-S0) energy gap. As a result, if there is no quenching effect of central metal atom, S1→S0 radiationless decay (internal conversion) has only minor contribution, if any, to the S1 state deactivation. Sometimes, however, one can find evidences in literature that (metal-free) symmetric close-spaced porphyrin dimers, used as models of photosynthetic structures, exhibit quenched S1 state, in spite of quite normal long-lived photophysics of initial monomers. This effect usually either remained unexplained or was accounted for by a participation of some “accepting intermolecular vibration mode” in the S1 state deactivation [1]. We believe, however, that, due to steric hindrances, close-spaced tetrapyrrol dimers can have strongly distorted macrocycles, and after excitation, structural relaxation can occur resulting in decrease of S1-S0 energy gap and corresponding increase of S1→S0 internal conversion rate. Recently synthesized [2] ethylene-bridged porphyrin dimers, EBPDs, of side-to-side geometry (see Fig.1) can be considered as a striking example of such unknown earlier for tetrapyrrol systems photoisomerisation-like photophysics.

Keywords

Toluene Porphyrin Meso Macrocycle Stilbene 

References

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    S.G. Boxer. BBA 726, 265 (1983).Google Scholar
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    A.M. Shulga, G.V. Ponomarev. Chem. Heterocycl. Compounds. 24, 276 (1988).CrossRefGoogle Scholar
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    M. Chachisvilis, V.S. Chirvony, A.M. Shulga, B. Kállebring, S. Larsson, V. Sundström. J.Phys.Chem. 100 (1996) in press.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • V. S. Chirvony
    • 1
  • M. Chachisvilis
    • 2
  • A. M. Shulga
    • 1
  • B. Källebring
    • 3
  • S. Larsson
    • 4
  • V. Sundström
    • 2
  1. 1.Institute of Molecular and Atomic PhysicsAcademy of Sciences of BelarusMinskBelarus
  2. 2.Department of Chemical Physics, Chemical CenterLund UniversityLundSweden
  3. 3.Department of Biochemistry and BiophysicsChalmers University of TechnologyGothenburgSweden
  4. 4.Department of Physical ChemistryChalmers University of TechnologyGothenburgSweden

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