Temperature dependence of the excited-state intramolecular proton transfer reaction in hypericin and hypocrellin A

Article Abstract:

The naturally occurring quinones hypericin and hypocrellin are known to induce antiviral and antitumor activity. For this reason, their proton-transfer reactions have been examined previously using various spectroscopic methods, leading to the conclusion that intramolecular excited-state proton transfer is a dominant nonradiative process in both of these polycyclic quinones. Their proton-transfer reactions are further elaborated using 1:1 mixtures of ethanol and methanol to demonstrate the temperature dependence of these excited-state reactions.

Excited state chemistry, Alcohols

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Hypericin, hypocrellin, and model compounds: steady-state and time-resolved fluorescence anisotropies

Article Abstract:

The steady-state and time-resolved fluorescence anisotropies of hypericin, hypocrellin and five other model compounds were investigated. The steady-state excitation anisotropies for each of the analogues have an extensive minimum at -400 nm with a negative value. The value of the anisotropy is positive at the blue and red edges of the spectrum. The limiting anisotropies were found to be consistent with the corresponding steady-state values.

Anisotropy, Spectra, Fluorescence spectroscopy, Polycyclic compounds, Molecular spectra

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