title: Effect of chromophore-charge distance on the energy transfer properties of water-soluble conjugated oligomers.
abstract: The synthesis of 1,4-bis(9,9'-bis(3"-(N,N,N-trimethylammonium)-propyl)-2'-fluorenyl)benzene tetrabromide (C3), 1,4-bis(9,9'-bis(4"-(N,N,N-trimethylammonium)-butyl)-2'-fluorenyl)benzene tetrabromide (C4), 1,4-bis(9,9'-bis(6"-(N,N,N-trimethylammonium)-hexyl)-2'-fluorenyl)benzene tetrabromide (C6), and 1,4-bis(9,9'-bis(8"-(N,N,N-trimethylammonium)-octyl)-2'-fluorenyl)benzene tetrabromide (C8) is reported. Fluorescence energy transfer experiments between C3-C8 and the acceptors pentasodium 1,4-bis(4'(2",4"-bis(butoxysulfonate)-styryl)styryl)-2-(butoxysulfonate)-5-methoxybenzene (3), fluorescein labeled single-stranded DNA and fluorescein labeled double-stranded DNA in water, buffer, and methanol reveal the importance of hydrophobic and electrostatic forces in determining chromophore-chromophore close proximity. In water, the oligomers with longer side chain length show better energy transfer, as well as higher Stern-Volmer quenching constants (K(sv)), largely due to a stronger hydrophobic attraction between the optically active components. In methanol, the differences in energy transfer are leveled, and the oligomers with shorter side chain lengths show higher K(sv) values. Compounds C3, C4, C6, and C8 were also used to dissect the different contributors to DNA hybridization assays based on cationic conjugated polymers.
authors.affiliation: Institute for Polymers and Organic Solids, Departments of Chemistry and Materials, University of California-Santa Barbara, Santa Barbara, CA 93106, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Brent S
authors.initials: BS
authors.lastname: Gaylord
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.forename: Guillermo C
authors.initials: GC
authors.lastname: Bazan
mesh_terms: D001555:Benzene Derivatives / Q000138:chemical synthesis / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D019793:Fluorescein / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D009693:Nucleic Acid Hybridization / Q000379:methods; D000644:Quaternary Ammonium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D001555:Benzene Derivatives; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D000644:Quaternary Ammonium Compounds; D014867:Water; D004247:DNA; D019793:Fluorescein