title: Aggregation kinetics of extended porphyrin and cyanine dye assemblies.
abstract: The kinetics of J-aggregate formation has been studied for two chromophores, tetrakis-4-sulfonatophenylporphine in an acid medium and pseudoisocyanine on a polyvinylsulfonate template. The assembly processes differ both in their sensitivity to initiation protocols and in the reaction profiles they produce. The porphyrin's assembly kinetics, for example, displays an induction period unlike that of the cyanine dye. Two kinetic models are presented. For the porphyrin, an autocatalytic pathway in which the formation of an aggregation nucleus is rate-determining appears to be applicable; for the pseudoisocyanine dye, an equation derived for diffusion-limited aggregation of a fractal object satisfactorily fits the data. These models are shown to be useful for the analysis of kinetic data obtained for several biologically important aggregation processes.
authors.affiliation: Department of Chemistry, Swarthmore College, Swarthmore Pennsylvania 19081, USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Pasternack
authors.forename: C
authors.initials: C
authors.lastname: Fleming
authors.forename: S
authors.initials: S
authors.lastname: Herring
authors.forename: P J
authors.initials: PJ
authors.lastname: Collings
authors.forename: J
authors.initials: J
authors.lastname: dePaula
authors.forename: G
authors.initials: G
authors.lastname: DeCastro
authors.forename: E J
authors.initials: EJ
authors.lastname: Gibbs
mesh_terms: D000327:Adsorption / Q000187:drug effects; D006851:Hydrochloric Acid / Q000737:chemistry / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007700:Kinetics; D011108:Polymers / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry*; D013053:Spectrophotometry; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D011108:Polymers; D011145:Polyvinyls; D011166:Porphyrins; D011804:Quinolines; D013451:Sulfonic Acids; C100254:pseudoisocyanine; C008959:lyapolate; C016136:tetraphenylporphine sulfonate; D006851:Hydrochloric Acid