Effect of β-cyclodextrin on the chemistry of 3′,4′,7-trihydroxyflavylium
2013; Royal Society of Chemistry; Volume: 37; Issue: 10 Linguagem: Inglês
10.1039/c3nj00588g
ISSN1369-9261
AutoresNuno Basílio, Ana Fernandes, Víctor de Freitas, Sandra Gago, Fernando Piña,
Tópico(s)Photochromic and Fluorescence Chemistry
ResumoThe pH dependence of the network of chemical reactions involving 3′,4′,7-trihydroxyflavylium was studied and all the rate and equilibrium constants were determined in the presence and absence of β-cyclodextrin. The β-cyclodextrin increases the rate constant of the flavylium cation hydration to give the hemiketal and decreases the reverse rate constant (de-hydration). The quantum yield of the flavylium cation formation from irradiation of the trans-chalcone increases from 0.023 to 0.055, respectively, in the absence and presence of β-cyclodextrin. NMR spectral characterization of the inclusion complex between 3′,4′,7-trihydroxyflavylium and β-cyclodextrin was performed by ROESY and suggests a structure in which the hydroxyl substituents at positions 3′ and 4′ interact with the internal surface of the β-cyclodextrin.
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