Solubilization and photophysical and photochemical behaviour of depsides and depsidones in water and Brij-35 solutions at different pH values

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 1992-07, Vol.67 (2), p.245-254
• Main Authors: Hidalgo, M.E., Fernandez, E., Quilhot, W., Lissi, E.A.
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Intermediary metabolites. Miscellaneous; Other biological molecules
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/1010-6030(92)85233-K

Atranorine, pannarine and 1-chloropannarine are lichenic metabolites bearing ortho- hydroxybenzaldehyde chromophoric units. The photochemical and photophysical behaviour in aqueous solutions, as well as in Brij-35 solutions, is strongly pH dependent. At pH 2, the behaviour is similar to that observed in aprotic solvents. The singlet lifetimes are extremely short (less than 1 ns), fluorescence yields are low, and the compounds show high photostability. This behaviour is compatible with a fast intramolecular enolization. At pH 10, the absorption and emission spectra are red-shifted, the singlets are longer lived and fluorescence yields are higher. The compounds readily photodecompose. The possible role of these compounds in the lichen is discussed.