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Updated: Jun 15, 2026
Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies
Published on: November 27, 2013
Characterization of the 4'-hydroxynaphthoflavylium network of chemical reactions
Raquel Gavara1, Vesselin Petrov, Fernando Pina
1Departamento de Química, REQUIMTE, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal.
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.
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