title: Effect of interaction with micelles on the excited-state optical properties of zinc porphyrins and J-aggregates formation.
abstract: This work reports on the photophysical properties of zinc porphyrins meso-tetrakis methylpyridiniumyl (Zn(2+)TMPyP) and meso-tetrakis sulfonatophenyl (Zn(2+)TPPS) in homogeneous aqueous solutions and in the presence of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) micelles. The excited-state dynamic was investigated with the Z-scan technique, UV-Vis absorption, and fluorescence spectroscopy. Photophysical parameters were obtained by analyzing the experimental data with a conventional five-energy-level diagram. The interaction of the charged side porphyrin groups with oppositely charged surfactants can reduce the electrostatic repulsion between porphyrin molecules leading to aggregation, which affected the porphyrin characteristics such as absorption cross-sections, lifetimes and quantum yields. The interaction between anionic ZnTPPS with cationic CTAB micelles induced the formation of porphyrin J-aggregates, while this effect was not observed in the interaction of ZnTMPyP with SDS micelles. This difference is, probably, due to the difference in electrostatic repulsion between the porphyrin molecules. The insights obtained by these results are important for the understanding of the photophysical behavior of porphyrins, regarding potential applications in pharmacokinetics as encapsulation of photosensitizer for drug delivery systems and in its interaction with cellular membrane.
authors.affiliation: Instituto de Física, Universidade Federal de Goiás, Caixa Postal 131, 74001-970 Goiânia, GO, Brazil. pablo@if.ufg.br
authors.forename: P J
authors.initials: PJ
authors.lastname: Gonçalves
authors.forename: D S
authors.initials: DS
authors.lastname: Corrêa
authors.forename: P L
authors.initials: PL
authors.lastname: Franzen
authors.forename: L
authors.initials: L
authors.lastname: De Boni
authors.forename: L M
authors.initials: LM
authors.lastname: Almeida
authors.forename: C R
authors.initials: CR
authors.lastname: Mendonça
authors.forename: I E
authors.initials: IE
authors.lastname: Borissevitch
authors.forename: S C
authors.initials: SC
authors.lastname: Zílio
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D008665:Metalloporphyrins / Q000737:chemistry*; D008823:Micelles; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D002593:Cetrimonium Compounds; D008665:Metalloporphyrins; D008823:Micelles; D013501:Surface-Active Agents; C474512:zinc-tetrakis(p-sulfonatophenyl)porphyrin; C017802:zinc hematoporphyrin; D012967:Sodium Dodecyl Sulfate; C060088:zinc tetra(4-N-methylpyridyl)porphine; D000077286:Cetrimonium