Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers

We report on the preparation and characterization of a new family of hydrogen-bonded nematogenic liquid crystalline dimers. The dimers are supramolecular complexes that consist of a benzoic acid derivative, acting as the proton donor, featuring a spacer with seven methylene groups and a terminal dec...

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Main Authors: Christian Anders, Muhammad Abu Bakar, Tejal Nirgude, Mohamed Alaasar
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Crystals
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Online Access:https://www.mdpi.com/2073-4352/15/6/576
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author Christian Anders
Muhammad Abu Bakar
Tejal Nirgude
Mohamed Alaasar
author_facet Christian Anders
Muhammad Abu Bakar
Tejal Nirgude
Mohamed Alaasar
author_sort Christian Anders
collection DOAJ
description We report on the preparation and characterization of a new family of hydrogen-bonded nematogenic liquid crystalline dimers. The dimers are supramolecular complexes that consist of a benzoic acid derivative, acting as the proton donor, featuring a spacer with seven methylene groups and a terminal decyloxy chain, paired with an azopyridine derivative as the proton acceptor. The latter was either fluorinated or nonfluorinated with variable alkoxy chain length. The formation of a hydrogen bond between the individual components was confirmed using FTIR and <sup>1</sup>H NMR spectroscopy. All supramolecules were investigated for their liquid crystalline behaviour via a polarized optical microscope (POM) and differential scanning calorimetry (DSC). All materials exhibit enantiotropic nematic phases as confirmed by X-ray diffraction (XRD) and POM investigations. The nematic phase range depends strongly on the degree and position of fluorine atoms. Additionally, the supramolecules demonstrated a rapid and reversible transition between the liquid crystal phase and the isotropic liquid state because of <i>trans-cis</i> photoisomerization upon light irradiation. Therefore, this study presents a straightforward approach to design photo-responsive nematic materials, which could be of interest for nonlinear optics applications.
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institution Kabale University
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series Crystals
spelling doaj-art-fa2b6c92ca5e441d894c90c57b8b93b72025-08-20T03:24:39ZengMDPI AGCrystals2073-43522025-06-0115657610.3390/cryst15060576Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline DimersChristian Anders0Muhammad Abu Bakar1Tejal Nirgude2Mohamed Alaasar3Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle Saale, GermanyInstitute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle Saale, GermanyInstitute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle Saale, GermanyInstitute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle Saale, GermanyWe report on the preparation and characterization of a new family of hydrogen-bonded nematogenic liquid crystalline dimers. The dimers are supramolecular complexes that consist of a benzoic acid derivative, acting as the proton donor, featuring a spacer with seven methylene groups and a terminal decyloxy chain, paired with an azopyridine derivative as the proton acceptor. The latter was either fluorinated or nonfluorinated with variable alkoxy chain length. The formation of a hydrogen bond between the individual components was confirmed using FTIR and <sup>1</sup>H NMR spectroscopy. All supramolecules were investigated for their liquid crystalline behaviour via a polarized optical microscope (POM) and differential scanning calorimetry (DSC). All materials exhibit enantiotropic nematic phases as confirmed by X-ray diffraction (XRD) and POM investigations. The nematic phase range depends strongly on the degree and position of fluorine atoms. Additionally, the supramolecules demonstrated a rapid and reversible transition between the liquid crystal phase and the isotropic liquid state because of <i>trans-cis</i> photoisomerization upon light irradiation. Therefore, this study presents a straightforward approach to design photo-responsive nematic materials, which could be of interest for nonlinear optics applications.https://www.mdpi.com/2073-4352/15/6/576azopyridinehydrogen bondingfluorinenematic phaseliquid crystals
spellingShingle Christian Anders
Muhammad Abu Bakar
Tejal Nirgude
Mohamed Alaasar
Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
Crystals
azopyridine
hydrogen bonding
fluorine
nematic phase
liquid crystals
title Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
title_full Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
title_fullStr Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
title_full_unstemmed Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
title_short Nematic Phases in Photo-Responsive Hydrogen-Bonded Liquid Crystalline Dimers
title_sort nematic phases in photo responsive hydrogen bonded liquid crystalline dimers
topic azopyridine
hydrogen bonding
fluorine
nematic phase
liquid crystals
url https://www.mdpi.com/2073-4352/15/6/576
work_keys_str_mv AT christiananders nematicphasesinphotoresponsivehydrogenbondedliquidcrystallinedimers
AT muhammadabubakar nematicphasesinphotoresponsivehydrogenbondedliquidcrystallinedimers
AT tejalnirgude nematicphasesinphotoresponsivehydrogenbondedliquidcrystallinedimers
AT mohamedalaasar nematicphasesinphotoresponsivehydrogenbondedliquidcrystallinedimers