INTERACTION OF IODINE WITH AEROSOL-OT IN REVERSED MICELLES IN N-HEXANE

The interaction between iodine and AOT in reversed micelle solutions o f AOT in n-hexane is reported. The absorption spectrum of iodine exhib its two bands in n-hexane: lambda(max) = 520 and 290 nm. When AOT is a dded a new absorption band appears at 385 nm. This band shifts hypsoch romically and its intensity increases when the surfactant concentratio n is increased. The intensity of the 290-nm band also increases while that of the 520-nm band decreases. The existence of an isosbestic poin t at 488 nm may indicate an equilibrium between the iodine and the sur factant. When water is added to AOT-I2 solution in n-hexane the lambda (max) of the band at 380 nm at W = 0 shifts to 360 nm at W = 15, while its intensity dramatically decreases. Also, the band intensity at 290 nm decreases while that at 520 nm increases. The isosbestic point obs erved without water is maintained. Thus, water seems to decrease the m agnitude of the interaction observed on increasing [AOT]. These result s are interpreted in terms of the formation of electron donor-acceptor complexes between AOT and 12. A strong 1:1 outer complex that develop s in a 1:2 inner complex depending on the relative concentrations of 1 2 and AOT micelles is proposed. Both complexes seem to be formed at th e micelle interface, showing a microenvironment polarity dependency. T he changes are much more significant in the micelle domain (at W < 10) than in the microemulsion domain. This interaction has been quantifie d as a function of W and AOT concentration. (C) 1994 Academic Press, I nc.