title: Structural basis for aggregation mode of oligo-p-phenylene ethynylenes with ionic surfactants.
abstract: In this letter, the aggregation modes of two classes of ionic p-phenylene ethynylene oligomers with oppositely charged surfactants are studied. The location of the ionic side chains was found to influence the type of aggregate formed when an equivalent number of surfactant molecules are added to solution. When the charged groups were located at the terminal ends of the molecule, strong H-aggregates were observed to form. Alternatively, when the ionic groups were both located on opposite sides of the central phenyl ring, the formation of J-aggregates was observed. Interestingly, as the surfactant concentration approaches the critical micelle concentration, the weakly bound aggregates are dissociated and the absorbance spectrum returns to what is observed in water. This study reveals the structural basis for aggregation effects between molecules based on the p-phenylene ethynylene backbone, and gives an understanding of how to influence the aggregation mode of similar compounds.
authors.affiliation: Center for Biomedical Engineering, Department of Chemical and Nuclear Engineering and ‡The Nanoscience and Microsystems Engineering Program and Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131-1341, United States.
authors.forename: Eric H
authors.initials: EH
authors.lastname: Hill
authors.forename: Dominic
authors.initials: D
authors.lastname: Sanchez
authors.forename: Deborah G
authors.initials: DG
authors.lastname: Evans
authors.forename: David G
authors.initials: DG
authors.lastname: Whitten
mesh_terms: D008823:Micelles; D011108:Polymers / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D008823:Micelles; D011108:Polymers; D013501:Surface-Active Agents; C473966:poly(phenylene ethynylene)