Generalization of the anthocyanins kinetics and thermodynamics multistate to 2,6-bis(2-hydroxybenzylidene)cyclohexanones

A. Alejo-Armijo, Artur J. Moro, A. Jorge Parola, João Carlos Lima, Fernando Pina, Livia Corici, Sergiu Shova, Liliana Cseh

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The thermodynamic and kinetic behavior of 4-(2,4-dihydroxybenzylidene)-6-hydroxy-1,2,3,4-tetrahydroxanthylium chloride was studied in detail. Similarly to anthocyanins, this compound generates a multistate of species that are reversibly interconverted by pH stimuli. The multistate system was studied by NMR and UV–visible (conventional spectroscopy and stopped-flow techniques). A theoretical approach adapted from the one reported for anthocyanins and related compounds was used to rationalize the complex multistate. In particular, the thermodynamic diagram where all the species are positioned was extended to the ionized species. Cis and trans isomers of flavylium cation, quinoidal bases, and ionized chalcone at extremely high pH values were identified. The multistate is dominated in the range 5 < pH < 8 by the spiro form in equilibrium with a small fraction of quinoidal bases. The spiro opening rates follow a different route and pH dependence in very acidic or moderately acidic pHs.

Original languageEnglish
Pages (from-to)573-588
Number of pages16
JournalDyes and Pigments
Publication statusPublished - 1 Apr 2019


  • Anthocyanins
  • Curcumin analogue
  • Flavylium cation
  • Spiro compounds
  • Stopped-flow


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