AGGREGATION OF AN AZO DYE IN AQUEOUS-SOLUTION

The investigation of the aggregation of a simple monoazo dye carrying fluorine atoms was performed by means of **1**9F nuclear magnetic resonance spectroscopy. As the concentration of the dye increased, the signals of the fluorine showed progressive shifts to the higher field. From the changes in shift it is concluded that the fluorine atoms are oriented above an adjacent aromatic nucleus. The results of the visible absorption spectroscopy indicate that the dye solutions are a polydispersed system. The equilibrium constant of the aggregation was estimated on the basis of an isodesmic model. A molecular model of the aggregates was proposed.