Why do flavylium salts show so various colors in solution?: Effect of concentration and water on the flavylium’s color changes

Abstract

When synthesized flavylium salts (FVs) were allowed to stand in an acetonitrile–water mixture, the color of the solutions changed from yellow to red via green. This color change in FV solution has been studied by observing the change in UV–VIS absorption spectra. In particular, change in the color from green to red depends on the concentration of FV and an amount of water. The solution color, however, changed from red to green on dehydration of the solution. It is concluded that water molecules are responsible for the change in solution color from green to red and the change is due to dimerization and/or aggregation of FVs.