Concentration-Dependent Association of Flavylium Chloride with Differential Hydroxy Moieties in Ethanol

Flavylium ions (6a–6e) were synthesized using Aldol condensation to compare the spectroscopic properties caused by different numbers and locations of hydroxy groups on flavylium cations (AH+). Without addition acid, increasing concentration 10 mM in ethanol led following observation. The with least number OH (6a 6b) showed a change peak at higher concentrations, whereas 6c 6d did not show same degree their 1H-NMR signals. This suggests an equilibrium that shifts isomers B, CE, Cz more towards ion even low concentrations. One possibility for cause this shift is become stable through aggregation. In NMR results, UV measurements confirmed fewer dramatic Using modeling data DFT//B3LYP/6311**G(d) level, self-association was investigated hydrogen bonding main player but cannot stabilize entirely without presence chloride complex.