The synthesis and reaction network of 2-styryl-1-benzopyrylium salts: An unexploited class of potential colorants

Investigation of the pH effect and UV radiation on kinetic degradation of anthocyanin mixtures extracted from Hibiscus acetosella

“…5(B) -pH 6.1. As explained before, the aromatic ring of C C structure is opened (Asenstorfer & Jones, 2007;Brouillard & Dubois, 1977;Brouillard et al, 1982;Dougall & Baker, 2008;Gomes et al, 2009;Maestri et al, 2000;Melo et al, 2002;Petrov et al, 2009). Nevertheless, the A À species was also detected up in samples exposed to UV radiation with similar behaviour, as previously observed for A À to the not-exposed samples.…”

“…5(B)), both clearly formed from the species AH + deprotonation. To the species represented by the dashed line in pH 2.4, 4.0 and 5.2, Pina et al (Gomes, Diniz, Jesus, Parola, & Pina, 2009;Maestri et al, 2000;Melo et al, 2002;Petrov, Gomes, Parola, & Pina, 2009) suggested that this species could be a different conformation of B species (see structures in Fig. 1), named as hemiketal B 4 , which can only be detected when samples were exposed to light.…”

A Photoelectrochemical Study of Bioinspired 2-Styryl-1-Benzopyrylium Cations on TiO2 Nanoparticle Layer for Application in Dye-Sensitized Solar Cells

“…Styrylflavylium salts 7-hydroxy-2-styryl-1-benzopyrylium tetrafluoroborate (GK1), 7-hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium chloride (GK2), and 7-hydroxy-2-(4-dimethylaminostyryl)-1benzopyrylium chloride (GK4) were available from previous studies [14,15]. Compounds 7-hydroxy -2-(4-methoxystyryl)-1-benzopyrylium perchlorate (GK3) and 7,8-dihydroxy-2-(4-dimethylaminostyryl)-1-benzopyrylium hydrogensulphate (GK5) were prepared from condensation of the respective salicylaldehydes and styrylmethylketones, according to published methodology [7].…”

“…Flavylium as well as styrylflavylium compounds are known to exist as chemical reaction networks where different chemical species are connected through several equilibria and the mole fraction distribution of species depends on the pH of the solution [7]. Figure 7 depicts this equilibria network for compound GK2 [14,15]. The styrylflavylium cation (AH + ) is the stable species at acidic pH values.…”

Synthesis, characterization and photochromism of 3′-butoxyflavylium derivatives

“…In recent years, a new family of photochromic compounds derived from 2-phenyl-1-benzopyrylium, the so-called synthetic flavylium compounds, have been reported in literature [2,3]. Synthetic flavylium compounds possess the same basic structure of anthocyanins, the ubiquitous colorants of most flowers and fruits and follow together with deoxyanthocyanins [4][5][6][7] styrylflavylium [8][9][10][11][12] and naphthoflavylium analogues [13,14], the same network of chemical reactions. The flavylium cation (red in anthocyanins), is stable only at very acidic pH values.…”