Solvent-free synthesis of aryl-substituted pyrylium salts and investigation of the auxochromes’ effects on their photophysical properties

Pyrylium compounds are structures based on an oxonium heterocycle that has been extensively studied thanks to their superior absorption and fluorescence properties. In this study, pyrylium salts were first shown to be obtained in the solvent-free medium. Six pyrylium compounds, three of which were novel, were synthesized using this method. These compounds have different auxochromes on the phenyl groups at the 2,4 and 6 positions. In the final step, the photophysical properties of these compounds were examined and the effects of basic auxochromes on pyrylium photophysics were revealed.