Bis[bis-(4-alkoxyphenyl)amino] derivatives of dithienylethene, bithiophene, dithienothiophene and dithienopyrrole: Palladium-catalysed synthesis and highly delocalised radical cations

Susan A. Odom, Kelly Lancaster, Luca Beverina, Kelly M. Lefler, Natalie J. Thompson, Veaceslav Coropceanu, Jean-Luc Bredas, Seth R. Marder, Stephen Barlow*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

Five diamines with thiophene-based bridges-(E)-1,2-bis-{5-[bis(4- butoxyphenyl)amino]-2-thienyljethylene (1), 5,5′-bis[bis(4-methoxyphenyl) amino]-2,2′-bithiophene (2), 2,6-bis[bis(4-butoxyphenyl)amino]dithieno[3, 2-b:2′,3′-d]thiophene (3), N-(4-tert-butylphenyl)-2,6-bis[bis(4- methoxyphenyl)amino]dithieno[3,2-b:2′,3′-d]pyrrole (4a) and N-tert-butyl-2,6-bis[bis(4-methoxyphenyl)amino]dithieno[3,2-b:2′, 3′-d]pyrrole (4b)-have been synthesised. The syntheses make use of the palladium(0)-catalysed coupling of brominated thiophene species with diarylamines, in some cases accelerated by microwave irradiation. The molecules all undergo facile oxidation, 4b being the most readily oxidised at about -0.4 V versus ferrocenium/ferrocene, and solutions of the corresponding radical cations were generated by addition of tris(4-bromophenyl)aminium hexachloroantimonate to the neutral species. The near-IR spectra of the radical cations show absorptions characteristic of symmetrical delocalised species (that is, class III mixed-valence species); analysis of these absorptions in the framework of Hush theory indicates strong coupling between the two amine redox centres, stronger than that observed in species with phenylenebased bridging groups of comparable length. The strong coupling can be attributed to high-lying orbitais of the thiophene-based bridging units. ESR spectroscopy indicates that the coupling constant to the amino nitrogen atoms is somewhat reduced relative to that in a stilbene-bridged analogue. The neutral species and the corresponding radical cations have been studied with the aid of density functional theory and time-dependent density functional theory. The DFT-calculated ESR parameters are in good agreement with experiment, while calculated spin densities suggest increased bridge character to the oxidation in these species relative to that in comparable species with phenylene-based bridges.

Original languageEnglish (US)
Pages (from-to)9637-9646
Number of pages10
JournalChemistry - A European Journal
Volume13
Issue number34
DOIs
StatePublished - Dec 7 2007

Keywords

  • Amination
  • Electron spin resonance
  • Mixed-valent compounds
  • Oxidation
  • Radicals

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint

Dive into the research topics of 'Bis[bis-(4-alkoxyphenyl)amino] derivatives of dithienylethene, bithiophene, dithienothiophene and dithienopyrrole: Palladium-catalysed synthesis and highly delocalised radical cations'. Together they form a unique fingerprint.

Cite this