Premium
EXCITED STATES OF ANTHOCYANINS: THE CHALCONE ISOMERS OF MALVIDIN 3,5‐DIGLUCOSIDE
Author(s) -
Lima J. C.,
Danesh Parvin,
Figueiredo Paulo,
Pina Fernando S.,
Maçanita António
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb05057.x
Subject(s) - chalcone , chemistry , fluorescence , excited state , photochemistry , protonation , anthocyanin , malvidin , spectroscopy , absorption spectroscopy , aqueous solution , fluorescence spectroscopy , analytical chemistry (journal) , stereochemistry , cyanidin , organic chemistry , ion , physics , food science , quantum mechanics , nuclear physics
The excited state properties of the chalcone isomers of malvidin 3,5‐diglucoside (malvin) in acidic aqueous solution (0 < pH < 4) were investigated using steady‐state and time‐resolved fluorescence spectroscopy. The two chalcone isomers of malvin were first isolated by high‐performance liquid chromatography and then characterized by UV/visible absorption and fluorescence spectroscopy. The results were supported by molecular orbital calculations. The rate constants for photodeprotonation ( k 1 = 1 × 10 9 s −l ) and protonation ( k −1 = 1.3 × 10 10 L mol −1 s −l ) were determined, both from the multiexponential fluorescence decays and the fluorescence intensities measured at the emission wavelengths of the neutral and ionized chalcone forms. The results here obtained are relevant for the understanding of the photoreactivity of anthocyanins in acidic medium.