Heterocyclic hydrophobic dyes and their interactions with surfactant and oil-in-water microemulsions

Starting from 2-methyl-6-alkylamidoquinolines containing alkyl chains in the range C 1 –C 15 , a series of styryl and symmetrical polymethine dyes was synthesized. Besides the characterization and a short discussion on physical and spectroscopic constants of dyes and of their intermediates, attention has been focussed on the aggregation of dyes in solution and on their interaction with amphiphilic systems. The dyes in water showed a marked tendency to form aggregates (even in the presence of fairly short alkyl chains) and the addition of anionic, cationic and nonionic surfactants (below, at and above their c.m.c.) did not afford satisfactory deaggregation. Preliminary, encouraging results were attained by resorting to oil-in-water microemulsions.