Issue 3, 2010

Characterization of the 4′-hydroxynaphthoflavylium network of chemical reactions

Abstract

The rate and equilibrium constants involved in the network of reactions of the 4′-hydroxynaphthoflavylium ion in moderately acidic and neutral media were characterized by means flash photolysis, stopped-flow and UV-vis absorption techniques. At the equilibrium, the network behaves as a two components system involving the naphthoflavylium ion and the trans-chalcone which is the thermodynamically stable species above pH = 2.9. All the rate and thermodynamic constants are very similar to those previously reported for 4′-hydroxyflavylium except the rate constant of the cis-trans isomerization which is much higher for the naphthoflavylium derivative. The lack of cis-trans isomerization barrier can be explained by the higher delocalization of the double bond between C(3) and C(4) charge through the naphthalene ring. Continuous irradiation experiments were carried out at the pH region that gives the higher photochromic efficiency.

Graphical abstract: Characterization of the 4′-hydroxynaphthoflavylium network of chemical reactions

Supplementary files

Article information

Article type
Paper
Submitted
19 Jun 2009
Accepted
14 Aug 2009
First published
06 Jan 2010

Photochem. Photobiol. Sci., 2010,9, 298-303

Characterization of the 4′-hydroxynaphthoflavylium network of chemical reactions

R. Gavara, V. Petrov and F. Pina, Photochem. Photobiol. Sci., 2010, 9, 298 DOI: 10.1039/B9PP00035F

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