Elucidation of the multiple equilibria of malvin in aqueous solution by One- and two-dimensional NMR

Helena Santos; David L. Turner; João C. Lima; Paulo Figueiredo; Fernando S. Pina; Antnio L. Maçanita

doi:10.1016/0031-9422(93)85054-U

Elucidation of the multiple equilibria of malvin in aqueous solution by One- and two-dimensional NMR

Helena Santos, David L. Turner, João C. Lima, Paulo Figueiredo, Fernando S. Pina, Antnio L. Maçanita

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Abstract

One- and two-dimensional NMR were used to characterize the several forms of malvin present in aqueous solution in the pH range 0.3-4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. The pathways for the interconversion of the different forms were derived and the molar absorbances of the species calculated by coupling NMR and UV/Vis data. Equilibrium constants were determined at different temperatures, and enthalpy and entropy changes were calculated for the interconversion processes. The conclusions are supported by molecular orbital calculations.

Original language	English
Pages (from-to)	1227-1232
Number of pages	6
Journal	Phytochemistry
Volume	33
Issue number	5
DOIs	https://doi.org/10.1016/0031-9422(93)85054-U
Publication status	Published - 23 Jul 1993

Keywords

Anthocyanins
malvin
multi-equilibria
two-dimensional NMR.

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title = "Elucidation of the multiple equilibria of malvin in aqueous solution by One- and two-dimensional NMR",

abstract = "One- and two-dimensional NMR were used to characterize the several forms of malvin present in aqueous solution in the pH range 0.3-4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. The pathways for the interconversion of the different forms were derived and the molar absorbances of the species calculated by coupling NMR and UV/Vis data. Equilibrium constants were determined at different temperatures, and enthalpy and entropy changes were calculated for the interconversion processes. The conclusions are supported by molecular orbital calculations.",

keywords = "Anthocyanins, malvin, multi-equilibria, two-dimensional NMR.",

author = "Helena Santos and Turner, {David L.} and Lima, {Jo{\~a}o C.} and Paulo Figueiredo and Pina, {Fernando S.} and Ma{\c c}anita, {Antnio L.}",

note = "This work was supported by grants from Junta National de Investigacao Cientifica e Tecno-logica (JNICT) and Instituto National de Investigacao Cientifica (INTC).",

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T1 - Elucidation of the multiple equilibria of malvin in aqueous solution by One- and two-dimensional NMR

AU - Santos, Helena

AU - Turner, David L.

AU - Lima, João C.

AU - Figueiredo, Paulo

AU - Pina, Fernando S.

AU - Maçanita, Antnio L.

N1 - This work was supported by grants from Junta National de Investigacao Cientifica e Tecno-logica (JNICT) and Instituto National de Investigacao Cientifica (INTC).

PY - 1993/7/23

Y1 - 1993/7/23

N2 - One- and two-dimensional NMR were used to characterize the several forms of malvin present in aqueous solution in the pH range 0.3-4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. The pathways for the interconversion of the different forms were derived and the molar absorbances of the species calculated by coupling NMR and UV/Vis data. Equilibrium constants were determined at different temperatures, and enthalpy and entropy changes were calculated for the interconversion processes. The conclusions are supported by molecular orbital calculations.

AB - One- and two-dimensional NMR were used to characterize the several forms of malvin present in aqueous solution in the pH range 0.3-4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. The pathways for the interconversion of the different forms were derived and the molar absorbances of the species calculated by coupling NMR and UV/Vis data. Equilibrium constants were determined at different temperatures, and enthalpy and entropy changes were calculated for the interconversion processes. The conclusions are supported by molecular orbital calculations.

KW - Anthocyanins

KW - malvin

KW - multi-equilibria

KW - two-dimensional NMR.

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JO - Phytochemistry

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IS - 5

ER -

Elucidation of the multiple equilibria of malvin in aqueous solution by One- and two-dimensional NMR

Abstract

Keywords

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