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.

Fernandez-Palacio F., Poutanen M., Saccone M., Siiskonen A., Terraneo G., Resnati G., et al. (2016). Efficient light-induced phase transitions in halogen-bonded liquid crystals. CHEMISTRY OF MATERIALS, 28(22), 8314-8321 [10.1021/acs.chemmater.6b03460].

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

Saccone M.
Supervision
;
2016-01-01

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.
Settore CHIM/07 - Fondamenti Chimici Delle Tecnologie
https://pubs.acs.org/doi/10.1021/acs.chemmater.6b03460#
Fernandez-Palacio F., Poutanen M., Saccone M., Siiskonen A., Terraneo G., Resnati G., et al. (2016). Efficient light-induced phase transitions in halogen-bonded liquid crystals. CHEMISTRY OF MATERIALS, 28(22), 8314-8321 [10.1021/acs.chemmater.6b03460].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/398664
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