Related Experiment Video
Updated: Jun 3, 2026
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Protic equilibria as the key factor of quercetin emission in solution. Relevance to biochemical and analytical
Alberto Mezzetti1, Stefano Protti, Christine Lapouge
1Laboratoire de Photocatalyse et Biohydrogène, SB2SM, CNRS URA 2096, CEA-Saclay, DSV/iBiTecS, 91191 Gif-sur-Yvette cedex, France. alberto.mezzetti@cea.fr
Abstract:
A detailed spectrofluorimetric study on quercetin in aqueous solution proves that its anionic forms are responsible for a strong fluorescence enhancement observed at pH > 6. Anion fluorescence is also observed in organic solvents with strong hydrogen bond acceptor properties. The results provide a new interpretation of biophysical and analytical literature data where the fluorescence of the anionic forms of quercetin has never been explicitly taken into account. In particular, comparison with published binding studies strongly suggests that quercetin deprotonation and consequent fluorescence enhancement takes place when the flavonoid binds to several biological macromolecules. This observation can be very helpful in the understanding at a molecular level of the interaction between quercetin and the biomolecule.
Related Concept Videos
Reaction Quotient
Variables Affecting Phosphorescence and Fluorescence
The Equilibrium Binding Constant and Binding Strength
Photoluminescence: Applications
Calculating the Equilibrium Constant
For example, gaseous nitrogen dioxide forms dinitrogen tetroxide according to this equation:
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
