title: Chiroptical properties of poly(p-phenyleneethynylene) copolymers in thin films: large g-values.
abstract: A series of chirally substituted poly (p-phenyleneethynylene) copolymers was prepared by alkyne metathesis of mixtures of two different 2,5-dialkyl-1,4-dipropynylbenzenes. One of the monomers was the chiral bis-2,5-(S)-3,7-dimethyloctyl-1,4-dipropynylbenzene, and the second one was an achiral dipropynyl monomer. If the content of chiral monomer is 25-50 mol %, unusually large chiroptical effects, that is, optical dissymmetries, result in absorption (g = -0.38) and emission (g = -0.19) of these copolymers. The large dissymmetries can be explained by a supramolecular ordering of the PPEs into stranded features that are visualized by dark-field transmission electron microscopy. The strands of chirally substituted PPEs display a striated structure that suggests that the whole feature is a single chirally twisted crystallite.
authors.affiliation: Department of Chemistry and Biochemistry, The University of South Carolina, Columbia, South Carolina 29208, USA.
authors.forename: James N
authors.initials: JN
authors.lastname: Wilson
authors.forename: Winfried
authors.initials: W
authors.lastname: Steffen
authors.forename: Trent G
authors.initials: TG
authors.lastname: McKenzie
authors.forename: Günter
authors.initials: G
authors.lastname: Lieser
authors.forename: Masao
authors.initials: M
authors.lastname: Oda
authors.forename: Dieter
authors.initials: D
authors.lastname: Neher
authors.forename: Uwe H F
authors.initials: UH
authors.lastname: Bunz