Confirmation of excited-state proton transfer and ground-state heterogeneity in hypericin by fluorescence upconversion

D. S. English, K. Das, K. D. Ashby, J. Park, J. W. Petrich, E. W. Castner

Research output: Contribution to journalArticle

68 Citations (Scopus)


Fluorescence upconversion measurements of hypericin and its methylated analog, O-hexamethoxyhypericin, which possesses no labile protons, confirm excited-state proton (or hydrogen atom) transfer as the primary photophysical event in hypericin. The presence of a rising component in the time-resolved fluorescence of hypericin and the absence of such a component for the hexamethoxy analog are consistent with our assignment of excited state proton or atom transfer as the primary photophysical process in the light-activated antiviral compound, hypericin. The results using the fluorescence upconversion technique, which detects only emission front the excited state, are in good agreement with our previous transient absorbance measurements. The results are also consistent with a heterogeneous ground state of hypericin.

Original languageEnglish
Pages (from-to)11585-11590
Number of pages6
JournalJournal of the American Chemical Society
Issue number48
Publication statusPublished - Dec 1 1997


ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this