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.

Interaction between Poly(9,9-bis(6′-N,N,N-trimethylammonium)hexyl)fluorene phenylene) Bromide and DNA as Seen by Spectroscopy, Viscosity, and Conductivity: Effect of Molecular Weights and DNA Secondary Structure

“…17 We assume, in agreement with previous reports, 18 that almost quantitative conversion of the neutral copolymer into the cationic one (HTMA-PFP) occurred, and that did not affect the degree of polymerization.…”

Highly fluorescing solid DNA-cationic polyelectrolyte complexes prepared from a natural DNA and a poly(fluorenevinylene-alt-phenylene) bearing quaternary ammonium pendants

“…Such fluorescence amplification has been reported and discussed for many other DNA-polyelectrolytes 29 or fluorescent intercalator mixtures. 22,23 In addition, there is a possibility for Föster resonance energy transfer or fluorescence resonance energy transfer (FRET) 28 between the surrounding DNA molecules and embedded Q chains. DNA emission although its intensity may be insignificant, overlaps well with the absorption range (300-475 nm) of the polymer Q, which favors the FRET process.…”

“…E-mail: jijin@korea.ac.kr with soluble polyconjugated polyelectrolyte, in particular, are closely related with those described in this report. [27][28][29] In this report, we would like to discuss the fluorescence properties of a series of solid mixtures of a natural DNA partially complexed with a water-soluble fluorescing polyconjugated polymer (polymer Q 30 whose structure is shown below in Figure 2) that bears quaternary ammonium pendant groups ( Figure 1). Applications of polyelectrolyte polymers are very diverse, which can be found elsewhere.…”

“…Since natural DNA is water-soluble polyelectrolyte, their complexes or mixtures with other water-soluble polyelectrolyte or amphiphilic compounds have been studied with regard to DNA detection or optical sensors, 26 energy transfer, 27,28 and fluorescence amplification. 23,27,29 DNA complexes *Corresponding Author.…”

Optical, electro-optic and optoelectronic properties of natural and chemically modified DNAs

“…This result indicates the presence of an extremely efficient energy transfer from the excited state of the Cz unit (donor) to the PVP units (acceptor) via the socalled fluorescence resonance energy transfer (FRET) or Förster energy transfer mechanism. 35 The proximity of the donor-acceptor fluorophore pairs must promote efficient electronic interactions between them to result in a facile FRET. The special organization of the donor and acceptor moieties must be a key factor.…”