Efficient light-induced phase transitions in halogen-bonded liquid crystals

Research output: Contribution to journalArticleScientificpeer-review


  • Francisco Fernandez-Palacio
  • Mikko Poutanen
  • Marco Saccone
  • Antti Siiskonen
  • Giancarlo Terraneo
  • Giuseppe Resnati
  • Olli Ikkala
  • Pierangelo Metrangolo
  • Arri Priimägi

Research units

  • Polytechnic University of Milan
  • VTT Technical Research Centre of Finland
  • Tampere University of Technology


Here, we present a new family of light-responsive, fluorinated supramolecular liquid crystals (LCs) showing efficient and reversible light-induced LC-to-isotropic phase transitions. Our materials design is based on fluorinated azobenzenes, where the fluorination serves to strengthen the noncovalent interaction with bond-accepting stilbazole molecules, and increase the lifetime of the cis-form of the azobenzene units. The halogen-bonded LCs were characterized by means of X-ray diffraction, hot-stage polarized optical microscopy, and differential scanning calorimetry. Simultaneous analysis of light-induced changes in birefringence, absorption, and optical scattering allowed us to estimate that <4% of the mesogenic units in the cis-form suffices to trigger the full LC-to-isotropic phase transition. We also report a light-induced and reversible crystal-to-isotropic phase transition, which has not been previously observed in supramolecular complexes. In addition to fundamental understanding of light-responsive supramolecular complexes, we foresee this study to be important in the development of bistable photonic devices and supramolecular actuators.


Original languageEnglish
Pages (from-to)8314-8321
Number of pages8
JournalChemistry of Materials
Issue number22
Publication statusPublished - 22 Nov 2016
MoE publication typeA1 Journal article-refereed

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