title: Synthesis, characterisation and electrical properties of supramolecular DNA-templated polymer nanowires of 2,5-(bis-2-thienyl)-pyrrole.
abstract: Supramolecular polymer nanowires have been prepared by using DNA-templating of 2,5-(bis-2-thienyl)-pyrrole (TPT) by oxidation with FeCl(3) in a mixed aqueous/organic solvent system. Despite the reduced capacity for strong hydrogen bonding in polyTPT compared to other systems, such as polypyrrole, the templating proceeds well. FTIR spectroscopic studies confirm that the resulting material is not a simple mixture and that the two types of polymer interact. This is indicated by shifts in bands associated with both the phosphodiester backbone and the nucleobases. XPS studies further confirm the presence of DNA and TPT, as well as dopant Cl(-) ions. Molecular dynamics simulations on a [{dA(24):dT(24)}/{TPT}(4)] model support these findings and indicate a non-coplanar conformation for oligoTPT over much of the trajectory. AFM studies show that the resulting nanowires typically lie in the 7-8 nm diameter range and exhibit a smooth, continuous, morphology. Studies on the electrical properties of the prepared nanowires by using a combination of scanned conductance microscopy, conductive AFM and variable temperature two-terminal I-V measurements show, that in contrast to similar DNA/polymer systems, the conductivity is markedly reduced compared to bulk material. The temperature dependence of the conductivity shows a simple Arrhenius behaviour consistent with the hopping models developed for redox polymers.
authors.affiliation: Chemical Nanoscience Laboratories, School of Chemistry, Newcastle University, Newcastle, NE1 7RU, UK.
authors.forename: Scott M D
authors.initials: SM
authors.lastname: Watson
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Hedley
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Galindo
authors.forename: Said A F
authors.initials: SA
authors.lastname: Al-Said
authors.forename: Nick G
authors.initials: NG
authors.lastname: Wright
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Connolly
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Horrocks
authors.forename: Andrew
authors.initials: A
authors.lastname: Houlton
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004553:Electric Conductivity; D005290:Ferric Compounds / Q000737:chemistry*; D008968:Molecular Conformation; D053770:Nanowires / Q000737:chemistry*; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: C577872:2,5-(bis-2-thienyl)-pyrrole; D002712:Chlorides; D005290:Ferric Compounds; D011108:Polymers; D011758:Pyrroles; D004247:DNA; C024555:ferric chloride