title: Fluorescence of acridinic dyes in anionic surfactant solution.
abstract: The interaction of the cationic dyes acridine, 9-aminoacridine (9AA), and proflavine, with sodium dodecyl sulfate (SDS) was studied by electronic absorption, steady-state and time-resolved fluorescence spectroscopies. The dyes interact with SDS in the pre-micellar region leading in two cases to dimerization in dye-surfactant aggregates, but with distinct molecular arrangements. For proflavine, the observed red shift of the electronic absorption band indicates the presence of J-aggregate, which are nonfluorescent. In the case of 9AA, the aggregates were characterized as nonspecific (neither J- nor H-type is spectroscopically observed). The time-resolved emission spectra gives evidences of the presence of weakly bound dimers by the recovery of three defined decay times by global analysis: dye monomer (tau1 = 16.4 ns), dimer (tau2 = 7.1 ns), and a faster component (tau3 = 2.1 ns) ascribed to intracluster energy migration between monomer and dimer. Acridine has a weak interaction with SDS forming only an ion pair without further self-aggregation of the dye.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Fisico-Quimica, Av. Trabalhador So Carlense 400, São Carlos 13566590, SP, Brazil.
authors.forename: Robson Valentim
authors.initials: RV
authors.lastname: Pereira
authors.forename: Marcelo Henrique
authors.initials: MH
authors.lastname: Gehlen
mesh_terms: D000166:Acridines / Q000737:chemistry*; D000585:Aminacrine / Q000737:chemistry*; D000586:Amination; D000838:Anions / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry*; D005453:Fluorescence; D015394:Molecular Structure; D011370:Proflavine / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000166:Acridines; D000838:Anions; D004396:Coloring Agents; D012996:Solutions; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D000585:Aminacrine; D011370:Proflavine