LUMINESCENCE CHARACTERISTICS OF 5-AMINOINDAZOLE IN CATIONIC AND ANIONIC MICELLES AT VARIOUS PH

Fluorescence characteristics of 5-aminoindazole (5-INH2) have been stu died at various acid-base concentrations in sodium dodecyl sulfate and cetyltrimethylammonium bromide (CTAB). The decrease in the fluorescen ce quantum yields of 5-INH2 in CTAB at pH 9 is partly due to the effec t of the medium and partly due to bromide ion-induced fluorescence que nching. Interaction of this amine with detergent molecules at pH 9 lea ds to premicellar formation. Prototropic reactions in the micellar int erface in S-0 and S-1 states involve the protonation and deprotonation of the amino group only. Biprotonic phototautomerism of singly proton ated species is not observed in the micellar interface. Apparent pK(a) values, which were determined for both equilibrium reactions, are dis cussed. (C) 1995 Academic Press, Inc.