Towards photocontrol over the helix-coil transition in foldamers: Synthesis and photoresponsive behavior of azobenzene-core amphiphilic oligo(meta-phenylene ethynylene)s

Anzar Khan, Stefan Hecht

Research output: Contribution to journalArticle

79 Citations (Scopus)

Abstract

Introduction of photochromic azobenzene units into amphiphilic oligo(meta-phenylene ethynylene)s allowed photocontrol over the helix-coil transition in this important class of foldamers. Two design principles were followed in efforts to accommodate cis- and trans-azobenzene moieties within the helical structure to selectively turn the helical state on and off, respectively. Several oligomer series with varying connectivities to the central azobenzene chromophore were synthesized and these photochromic oligomers were investigated with regard to their folding behavior in both dark and irradiated states. Both the foldamers' chain lengths and the electronic structures of the azobenzene moieties had to be optimized to ensure folding differences and selective excitation of the photochrome. The design of such stimuli-responsive macromolecules, displaying large structural changes upon irradiation, should guide the design of future materials in, for example, "smart" delivery applications.

Original languageEnglish
Pages (from-to)4764-4774
Number of pages11
JournalChemistry - A European Journal
Volume12
Issue number18
DOIs
Publication statusPublished - 2006 Jun 14

Keywords

  • Azo compounds
  • Chirality
  • Foldamers
  • Helical structures
  • Photochromism

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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