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

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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2016-11-22
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Language
en
Pages
8
8314-8321
Series
Chemistry of Materials, Volume 28, issue 22
Abstract
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.
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Fernandez-Palacio , F , Poutanen , M , Saccone , M , Siiskonen , A , Terraneo , G , Resnati , G , Ikkala , O , Metrangolo , P & Priimägi , A 2016 , ' Efficient light-induced phase transitions in halogen-bonded liquid crystals ' , Chemistry of Materials , vol. 28 , no. 22 , pp. 8314-8321 . https://doi.org/10.1021/acs.chemmater.6b03460