substituents at the position 2 were synthesized. Their absorption and fluorescence
properties were studied in solvents of medium and high polarity. Almost all the synthesized
3HQs display dual fluorescence in the tested solvents, in line with an excited state
intramolecular proton transfer reaction. For N-methyl substituted compounds, the intensity
ratio of the two emission bands was found to be exquisitely sensitive to solvent polarity, with …