title: The interaction of 2-hydroquinone-5,10,15,20-tetra(p-hydroxyphenyl)porphyrin with surfactants: solubilization and J-aggregates.
abstract: J-aggregates of 2-hydroquinone-5,10,15,20-tetra(p-hydroxyphenyl)porphyrin (HQTHPP) induced by N-lauroyl sarcosine (SKL) in aqueous neutral solutions have been studied by optical absorption, fluorescence, and resonance light-scattering spectroscopies. As SKL concentration increases, the spectra evolve to reveal the presence of four independent species with relative concentration. The most important species is J-aggregates. The J-aggregates have two strong exciton bands corresponding to the B-band and Q-bands of HQTHPP monomers, and are found to be stable when the surfactant concentration is below 8.0 mmol/L. But above 8.0 mmol/L, the J-aggregates dissolve gradually into another species: porphyrin monomers. The total fluorescence of HQTHPP is quenched due to the aggregate formation. A strong and sharply peaked resonance light-scattering signal (>1800 counts/s, centered at 490 nm) is observed just slightly to the red of the J-aggregate absorption maximum. In the case of cetyltrimethyl-ammonium bromide, increasing surfactant concentrations have only shown to favor solubilization of porphyrin monomers. Evidently, the nature of polar headgroups of surfactants influences the tendency of THPP to aggregate.
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan 430072, PR China.
authors.forename: Xiwen
authors.initials: X
authors.lastname: Li
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Xie
authors.forename: Zhangping
authors.initials: Z
authors.lastname: Chen
authors.forename: Guolin
authors.initials: G
authors.lastname: Zou
mesh_terms: D002412:Cations / Q000737:chemistry; D006873:Hydroquinones / Q000737:chemistry*; D008027:Light; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D012542:Scattering, Radiation; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: C504548:2-hydroquinone-5,10,15,20-tetra(p-hydroxyphenyl)porphyrin; D002412:Cations; D006873:Hydroquinones; D011166:Porphyrins; D012996:Solutions; D013501:Surface-Active Agents