Long chain heterocyclic dyes. Part one. Hydrophobic structures

A series of polymethine dyes and of their precursors, containing long and short alkyl chains, was prepared and their chemical and spectroscopic (uv, 1 H‐nmr) properties were briefly discussed. The electronic absorption spectra of the dyes in aqueous medium and in presence of anionic or cationic surfactants evidenced aggregation phenomena. The best deaggregating effect was shown by the anionic surfactant when added above its critical micellar concentration.