Fluorescence spectra and decays of malvidin 3,5-diglucoside in aqueous solutions

Abstract

The fluorescence properties of malvidin 3,5-diglucoside in aqueous solutions at various pH values were investigated using steady state and time-resolved fluorescence techniques.

Fluorescence emission bands were assigned to the flavylium cation (AH+) (λmax = 620 nm), hemiacetal (B) (λmax = 370 nm), chalcone (C) (λmax = 435 nm), ionized chalcone (C−) (λmax = 495 nm), quinonoidal base (A) (λmax = 660 nm) and ionized quinonoidal base (A−) (λmax = 665 nm) forms.

The fluorescence decays of these forms are, in general, multiexponential. In some cases, this is due to the overlap of more than one emission band, and in others indicates an excited state interconversion between some of these forms.