Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5416956 | Journal of Molecular Structure: THEOCHEM | 2010 | 4 Pages |
Abstract
Anthocyanins are natural pigments that present a characteristic red color at low pH (<2). Anthocyanin-pyruvic acid adducts, commonly referred to as vitisins, are anthocyanin derivatives usually found in red wines. Looking at the two-dimensional structures, vitisins apparently have a greater conjugation system than anthocyanins. Following the common conjugation rules, making the chromophore more conjugated increases the value of λmax, and vitisins should have a longer λmax than anthocyanins. However, they have a surprising lower λmax, presenting an orange color, under the same pH conditions. Another class of anthocyanin-derived pigments, portisins have the expected relative behaviour with a longer λmax than anthocyanins. In this work, a quantum study on molecular models of pigment models was carried out. The results obtained enabled to present a putative explanation of the color change in these series.
Keywords
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Alexandre R.F. Carvalho, Joana Oliveira, Victor de Freitas, Nuno Mateus, André Melo,