Electrophilicity and solvatochromic reversal of pyridinium phenolate betaine dyes

► The solvatochromic reversal can be predicted by the relative electrophilic Fukui functions of the dye structural moieties. ► As polarity increases, there is an inversion of the relative Fukui functions of the two moieties. ► The electrophilicity index ω may be used to distinguish the solvatochromic behavior of a phenolate betaine dye. ► Linear plots of ω against the dye solvation energy have slope values that increase in the order negative