title: A spectral approach to determine location and orientation of azo dyes within surfactant aggregates.
abstract: The UV-vis absorption properties of azo dyes are known to exhibit a variation with the polarity and acidity of the dye environment. The spectral properties of a series of anionic azo dyes were characterized to further probe the interaction of these dyes with two types of surfactant aggregates: (1) the spherical micelles formed in aqueous solution by alkyltrimethylammonium bromide (C(n)TAB) surfactants with n=10-16 and (2) the unilamellar vesicles spontaneously formed in water from binary mixtures of the oppositely-charged double-tailed surfactants cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium dioctylsulfosuccinate (Aerosol OT or AOT). The observed dye spectra reflect the solvatochromic behavior of the dyes and suggest the location and orientation of the dye within the surfactant aggregates. Deconvolution of the overall spectra into sums of Gaussian curves more readily displays any contributions of tautomeric forms of the azo dyes resulting from intramolecular hydrogen bonding. The rich variation in UV/vis absorption properties of these anionic azo dyes supports their use as sensitive tools to explore the nanostructures of surfactant aggregates.
authors.affiliation: Department of Chemistry, Harvey Mudd College, Claremont, CA 91711, USA. Kerry_Karukstis@hmc.edu
authors.forename: Kerry K
authors.initials: KK
authors.lastname: Karukstis
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Litz
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Garber
authors.forename: Laura M
authors.initials: LM
authors.lastname: Angell
authors.forename: George K
authors.initials: GK
authors.lastname: Korir
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry*; D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry; D004560:Electricity; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013501:Surface-Active Agents / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D002593:Cetrimonium Compounds; D004396:Coloring Agents; D008823:Micelles; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D012997:Solvents; D013501:Surface-Active Agents; D053835:Unilamellar Liposomes; D004143:Dioctyl Sulfosuccinic Acid; C046112:didodecyldimethylammonium; D000077286:Cetrimonium