Display options
Cite
Tait CE, Neuhaus P, Peeks MD, et al. Transient EPR Reveals Triplet State Delocalization in a Series of Cyclic and Linear π-Conjugated Porphyrin Oligomers. J Am Chem Soc. 2015;137(25):8284-93doi: 10.1021/jacs.5b04511.
Tait, C. E., Neuhaus, P., Peeks, M. D., Anderson, H. L., & Timmel, C. R. (2015). Transient EPR Reveals Triplet State Delocalization in a Series of Cyclic and Linear π-Conjugated Porphyrin Oligomers. Journal of the American Chemical Society, 137(25), 8284-93. https://doi.org/10.1021/jacs.5b04511
Tait, Claudia E, et al. "Transient EPR Reveals Triplet State Delocalization in a Series of Cyclic and Linear π-Conjugated Porphyrin Oligomers." Journal of the American Chemical Society vol. 137,25 (2015): 8284-93. doi: https://doi.org/10.1021/jacs.5b04511
Tait CE, Neuhaus P, Peeks MD, Anderson HL, Timmel CR. Transient EPR Reveals Triplet State Delocalization in a Series of Cyclic and Linear π-Conjugated Porphyrin Oligomers. J Am Chem Soc. 2015 Jul 01;137(25):8284-93. doi: 10.1021/jacs.5b04511. Epub 2015 Jun 19. PMID: 26035477; PMCID: PMC4569062.
Copy Download .nbib Format: NLM
Share it on

J Am Chem Soc. 2015 Jul 01;137(25):8284-93. doi: 10.1021/jacs.5b04511. Epub 2015 Jun 19.

Transient EPR Reveals Triplet State Delocalization in a Series of Cyclic and Linear π-Conjugated Porphyrin Oligomers.

Journal of the American Chemical Society

Claudia E Tait, Patrik Neuhaus, Martin D Peeks, Harry L Anderson, Christiane R Timmel

Affiliations

  1. †Department of Chemistry, Centre for Advanced Electron Spin Resonance, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
  2. ‡Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.

PMID: 26035477 PMCID: PMC4569062 DOI: 10.1021/jacs.5b04511

Abstract

The photoexcited triplet states of a series of linear and cyclic butadiyne-linked porphyrin oligomers were investigated by transient Electron Paramagnetic Resonance (EPR) and Electron Nuclear DOuble Resonance (ENDOR). The spatial delocalization of the triplet state wave function in systems with different numbers of porphyrin units and different geometries was analyzed in terms of zero-field splitting parameters and proton hyperfine couplings. Even though no significant change in the zero-field splitting parameters (D and E) is observed for linear oligomers with two to six porphyrin units, the spin polarization of the transient EPR spectra is particularly sensitive to the number of porphyrin units, implying a change of the mechanism of intersystem crossing. Analysis of the proton hyperfine couplings in linear oligomers with more than two porphyrin units, in combination with density functional theory calculations, indicates that the spin density is localized mainly on two to three porphyrin units rather than being distributed evenly over the whole π-system. The sensitivity of the zero-field splitting parameters to changes in geometry was investigated by comparing free linear oligomers with oligomers bound to a hexapyridyl template. Significant changes in the zero-field splitting parameter D were observed, while the proton hyperfine couplings show no change in the extent of triplet state delocalization. The triplet state of the cyclic porphyrin hexamer has a much decreased zero-field splitting parameter D and much smaller proton hyperfine couplings with respect to the monomeric unit, indicating complete delocalization over six porphyrin units in this symmetric system. This surprising result provides the first evidence for extensive triplet state delocalization in an artificial supramolecular assembly of porphyrins.

References

  1. Chem Commun (Camb). 2013 Oct 28;49(84):9722-4 - PubMed
  2. J Am Chem Soc. 2015 May 27;137(20):6670-9 - PubMed
  3. Angew Chem Int Ed Engl. 2008;47(27):4993-6 - PubMed
  4. J Magn Reson. 2006 Jan;178(1):42-55 - PubMed
  5. J Am Chem Soc. 2009 Jul 29;131(29):10092-106 - PubMed
  6. Photochem Photobiol Sci. 2007 Jun;6(6):675-82 - PubMed
  7. J Am Chem Soc. 2002 Dec 11;124(49):14642-54 - PubMed
  8. Angew Chem Int Ed Engl. 2015 Jun 15;54(25):7344-8 - PubMed
  9. Acc Chem Res. 2000 Nov;33(11):791-804 - PubMed
  10. Acc Chem Res. 2002 Jan;35(1):57-69 - PubMed
  11. Philos Trans A Math Phys Eng Sci. 2012 Aug 13;370(1972):3802-18 - PubMed
  12. J Phys Chem Lett. 2014 Dec 18;5(24):4356-61 - PubMed
  13. Nature. 2000 Nov 30;408(6812):541-8 - PubMed
  14. Phys Rev Lett. 2003 Feb 7;90(5):057402 - PubMed
  15. J Am Chem Soc. 2006 Jul 5;128(26):8380-1 - PubMed
  16. J Phys Chem A. 2006 Nov 9;110(44):12267-75 - PubMed
  17. Nat Mater. 2007 Nov;6(11):841-50 - PubMed
  18. Biochem Biophys Res Commun. 1976 Nov 22;73(2):501-6 - PubMed
  19. Angew Chem Int Ed Engl. 2011 Nov 4;50(45):10522-53 - PubMed
  20. Nat Chem. 2015 Apr;7(4):317-22 - PubMed
  21. Biochim Biophys Acta. 2003 Aug 18;1605(1-3):35-46 - PubMed
  22. Nat Mater. 2008 Mar;7(3):179-86 - PubMed
  23. Acc Chem Res. 2004 Oct;37(10):735-45 - PubMed
  24. Nat Mater. 2005 Apr;4(4):335-9 - PubMed
  25. J Am Chem Soc. 2011 Dec 28;133(51):20962-9 - PubMed
  26. Nature. 2001 Oct 25;413(6858):828-31 - PubMed
  27. J Am Chem Soc. 2011 Nov 2;133(43):17262-73 - PubMed
  28. Science. 1994 May 20;264(5162):1105-11 - PubMed
  29. Chemphyschem. 2008 Feb 1;9(2):282-92 - PubMed

Publication Types

Grant support