The first examples of V-shaped compounds exhibiting a B 5 mesophase and a direct transition from the isotropic to a polar biaxial smectic A mesophase

Hegde, Rekha S.; Kumar, J.; Prasad, Veena; Monika, M.

doi:10.1016/j.molliq.2017.11.024

Cited by 7 publications

(2 citation statements)

References 36 publications

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“…However, when Cl is replaced with a highly electronegative fluorine atom, the compound BC-F of the present study exhibits enantiotropic nematic and smectic mesophases. Although it is stated that the effect of Cl is often similar to F on the mesomorphic properties, , in the present case, we found that the effect of F is much different from Cl. As can be seen, the compound BC-F exhibits a smectic mesophase in addition to a nematic mesophase.…”

Section: Resultscontrasting

confidence: 86%

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound

Kumar

Prasad

2018

J. Phys. Chem. B

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Here, we report the observation of ferroelectric nematic and ferrielectric smectic mesophases in an achiral bent-core azo compound consisting of nonsymmetrical molecules with a lateral fluoro substitution on one of the wings. These mesophases are enantiotropic in nature with fairly low transition temperatures and wide mesophase ranges. The liquid crystalline properties of this compound are investigated using polarizing optical microscope, differential scanning calorimeter, X-ray diffraction, and electro-optical studies. As revealed by X-ray diffraction measurements, the nematic mesophase is composed of skewed cybotactic clusters and, in the smectic mesophase, the molecules are tilted with respect to the layer normal. The polar order in these mesophases was confirmed by the electro-optical switching and dielectric spectroscopy measurements. The dielectric study in the nematic mesophase shows a single relaxation process at low frequency ( f < 1 kHz) measured in the range 10 Hz to 5 MHz, which is attributed to the collective motion of the molecules within cybotactic clusters. The formation of local polar order in these clusters leads to a ferroelectric-like polar switching in the nematic mesophase. Of particular interest is the fact that the smectic phase exhibits a field induced ferrielectric state, which can be exploited for designing of the potential optical devices due to multistate switching.

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Section: Resultscontrasting

confidence: 86%

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound

Kumar

Prasad

2018

J. Phys. Chem. B

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“…Studies regarding switching in the N b and SmA b LC phases are mostly limited to those of bent-core molecules, − disc-like molecules, − and mixtures of these molecules with rodlike molecules, − which are known to be effective. However, these core shape-assisted approaches have the problem of low electroresponsiveness due to the large excluded volume during molecular rotation.…”

Section: Introductionmentioning

confidence: 99%

Does Introduction of a Bent Tail Stabilize Biaxiality and Lateral Switching Behavior of Smectic A Liquid Crystal Phases of Rodlike Molecules?

et al. 2019

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By introducing an oleyl group at the end of the straight rodlike molecule, the effect of the tail shape on the liquid crystallinity, biaxiality, and lateral switching behavior of the smectic A phase was investigated. Three types of molecules possessing a fluorinated phenyl (pentafluorophenyl, 2,3,4-trifluorophenyl, or 2,3-difluorophenyl) group and a cis-octadec-9-enyl group were synthesized, and their liquid crystallinities were compared with the corresponding molecules with a straight alkyl (trans-octadec-9-enyl or n-octadecanyl) group. In switching experiments, the molecules with a bent terminal chain showed higher spontaneous polarization (P s) values than those with a straight terminal chain. Further, the directional changes of the long molecular axes were suppressed for the molecules possessing a bent terminal chain. These results show that the introduction of a bent terminal chain is highly effective for stabilizing ferroelectric switching behaviors.

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Influence of alkyl and alkoxy groups on photoresponsive behaviour of bent-core azo mesogens: Synthesis, mesomorphic and photoswitching properties

Hegde

Sunil²,

Hegde³

et al. 2020

Journal of Molecular Liquids

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The first examples of V-shaped compounds exhibiting a B 5 mesophase and a direct transition from the isotropic to a polar biaxial smectic A mesophase

Cited by 7 publications

References 36 publications

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound

Does Introduction of a Bent Tail Stabilize Biaxiality and Lateral Switching Behavior of Smectic A Liquid Crystal Phases of Rodlike Molecules?

Influence of alkyl and alkoxy groups on photoresponsive behaviour of bent-core azo mesogens: Synthesis, mesomorphic and photoswitching properties

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