Acid−Base and Aggregation Processes of Acridine Orange Base in n-Heptane/AOT/Water Reverse Micelles

The properties of the base acridine orange (AOB) in n-heptane/AOT/water reverse micelles were investigated by using absorption, fluorescence, and single photon counting techniques. For comparison, studies in homogeneous media (water and n-heptane) were also performed. The absorption spectra of AOB in water at pH 10 in the same [AOB] range, only the basic form, AOB, was detected with a band in the visible at λmax = 435 nm, which obeys Lambert−Beer's law. This species was also the only one detected in n-heptane at 417 nm. These results show that only the protonated base dimerizes as confirmed by fluorescence techniques. The absorption spectra of AOB in the micellar media at various W0 (W0 = [H2O]/[AOT]) and pH = 4, working above the operational critical micellar concentration and below [AOT] = 3 × 10-3 M, show the disappearance of the ban...