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Spectroscopic and computational study of β-ethynylphenylene substituted zinc and free-base porphyrins

Journal Article


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Abstract


  • A series of tetraphenylporphyrins appended at the β-pyrrolic position with an ethynylphenylene- or ethynylpyridine-substituent have been subjected to spectroscopic and density functional theory (DFT) analyses. The mean absolute deviation between corresponding experimental and DFT-derived vibrational spectra is up to 10.2 cm -1, suggesting that the DFT B3LYP/6-31G(d) method provides an accurate model of the β-substituted porphyrin systems. The configuration interactions that give rise to prominent electronic absorptions have been calculated using time-dependant DFT (TD-DFT) and have been rationalized with reference to the energy and topology of DFT calculated molecular orbitals. As the electron withdrawing capacity of the β-substituent increases the LUMO orbital gains appreciable amplitude over the substituent moiety and is stabilised. This represents a departure from the assumptions underpinning the Gouterman four-orbital model, resulting in atypical electronic absorption spectra. This phenomenon is also manifested in the enhancement patterns of the resonance Raman spectra insofar as B-band excitation engenders an enhancement of substituent based modes. These observations demonstrate that the β-substituent exerts an appreciable electronic influence on the porphyrin π-electron system and provides a means of introducing charge-transfer character to prominent electronic transitions. © 2011 the Owner Societies.

Authors


  •   Earles, John C. (external author)
  •   Gordon, Keith C. (external author)
  •   Stephenson, Adam (external author)
  •   Partridge, Ashton (external author)
  •   Officer, David L.

Publication Date


  • 2011

Citation


  • Earles, J. C., Gordon, K. C., Stephenson, A. W. I., Partridge, A. C. & Officer, D. L. (2011). Spectroscopic and computational study of β-ethynylphenylene substituted zinc and free-base porphyrins. Physical Chemistry Chemical Physics, 13 (4), 1597-1605.

Scopus Eid


  • 2-s2.0-78651341541

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2188&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1120

Number Of Pages


  • 8

Start Page


  • 1597

End Page


  • 1605

Volume


  • 13

Issue


  • 4

Abstract


  • A series of tetraphenylporphyrins appended at the β-pyrrolic position with an ethynylphenylene- or ethynylpyridine-substituent have been subjected to spectroscopic and density functional theory (DFT) analyses. The mean absolute deviation between corresponding experimental and DFT-derived vibrational spectra is up to 10.2 cm -1, suggesting that the DFT B3LYP/6-31G(d) method provides an accurate model of the β-substituted porphyrin systems. The configuration interactions that give rise to prominent electronic absorptions have been calculated using time-dependant DFT (TD-DFT) and have been rationalized with reference to the energy and topology of DFT calculated molecular orbitals. As the electron withdrawing capacity of the β-substituent increases the LUMO orbital gains appreciable amplitude over the substituent moiety and is stabilised. This represents a departure from the assumptions underpinning the Gouterman four-orbital model, resulting in atypical electronic absorption spectra. This phenomenon is also manifested in the enhancement patterns of the resonance Raman spectra insofar as B-band excitation engenders an enhancement of substituent based modes. These observations demonstrate that the β-substituent exerts an appreciable electronic influence on the porphyrin π-electron system and provides a means of introducing charge-transfer character to prominent electronic transitions. © 2011 the Owner Societies.

Authors


  •   Earles, John C. (external author)
  •   Gordon, Keith C. (external author)
  •   Stephenson, Adam (external author)
  •   Partridge, Ashton (external author)
  •   Officer, David L.

Publication Date


  • 2011

Citation


  • Earles, J. C., Gordon, K. C., Stephenson, A. W. I., Partridge, A. C. & Officer, D. L. (2011). Spectroscopic and computational study of β-ethynylphenylene substituted zinc and free-base porphyrins. Physical Chemistry Chemical Physics, 13 (4), 1597-1605.

Scopus Eid


  • 2-s2.0-78651341541

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2188&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1120

Number Of Pages


  • 8

Start Page


  • 1597

End Page


  • 1605

Volume


  • 13

Issue


  • 4