Liquid Crystalline State

Blinov, L. M.; Chigrinov, Vladimir G.

doi:10.1007/978-1-4612-2692-5_1

Cited by 6 publications

(1 citation statement)

References 49 publications

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“…A planarly aligned cell was kept under a microscope with crossed polarizers and the spectra for transmitted light as a function of wavelength were recorded at each temperature for measuring birefringence. The transmitted light through a cell containing the sample as a function of wavelength can be expressed as: [57,58] T ¼ I 0 sin 2 2a ð Þsin 2 pDnd l…”

Section: Birefringence Measurementsmentioning

confidence: 99%

Nematic Phase of Polar Unsymmetrical Bent‐Core Molecules

et al. 2023

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In liquid crystalline systems, the presence of polar groups at lateral or terminal positions is fundamentally and technologically important. Bent-core nematics composed of polar molecules with short rigid cores usually exhibit highly disordered mesomorphism with some ordered clusters that favourably nucleate within. Herein, we have systematically designed and synthesized two new series of highly polar bent-core compounds comprised of two unsymmetrical wings, highly electronegative À CN and À NO 2 groups at one end, and flexible alkyl chains at the other end. All the compounds showed a wide range of nematic phases composed of cybotactic clusters of smectic-type (N cyb ). The birefringent microscopic textures of the nematic phase were accompanied by dark regions. Further, the cybotactic clustering in the nematic phase was characterized via temperature-dependent XRD studies and dielectric spectroscopy. Besides, the birefringence measurements demonstrated the ordering of the molecules in the cybotactic clusters upon lowering the temperature. DFT calculations illustrated the favourable antiparallel arrangement of these polar bent-core molecules as it minimizes the large net dipole moment of the system.

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Section: Birefringence Measurementsmentioning

confidence: 99%

Nematic Phase of Polar Unsymmetrical Bent‐Core Molecules

et al. 2023

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UV Induced Photoalignment and Colour Change in Nematic Liquid Crystals with Provitamin D Dopant

Gvozdovskyy

Orlova

Terenetskaya

2005

Molecular Crystals and Liquid Crystals

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Adsorption of provitamin D 3 molecules at glass=quartz substrate surface of a LC cell provided uniform alignment of nematic LCs in homeotropic orientation that was changed to the planar one under linearly polarized UV irradiation. Reversible switching between the two orientations has been achieved by applied electric field. The effects revealed are usable in optical imaging and data storage, in LC display technology and other applications.

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Frustrated structure of an anticlinic-like smectic-C phase

Sebastião¹,

Carvalho

Chaves

et al. 2006

Eur. Phys. J. E

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We present a polarising optical microscopy study of the low-temperature anticlinic-like tilted mesophase of the liquid-crystal compound octylphenyl-2-chloro-4-(p-cyano-benzoyloxy) (DB8Cl). This mesophase has been described as a bilayer smectic structure in which the molecules within each layer are organised in an anticlinic way. The optical textures observed in samples with planar orientation show a double stripe pattern, with the lines aligned parallel to the rubbing direction, characteristic of a double periodic modulation of the refractive index of the material. The long-period modulation is temperature dependent and disappears for thin sample cells (< 5 microm). The short-period modulation is nearly independent of the thickness of the cells. The experimental results are analysed in terms of a model which considers that there is a special distribution of the principal optical axis which may be in or out of the polariser-analyser plane. The observed periodic variation of the principal optical axis could not be interpreted in terms of the original structure proposed for this phase. DB8Cl presents a structure formed by dimers that can be viewed as flexible bent-core-like molecules, showing similarities with phases found in banana-like systems, but exhibiting a much more complex structure.

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Liquid Crystalline State

Cited by 6 publications

References 49 publications

Nematic Phase of Polar Unsymmetrical Bent‐Core Molecules

Nematic Phase of Polar Unsymmetrical Bent‐Core Molecules

UV Induced Photoalignment and Colour Change in Nematic Liquid Crystals with Provitamin D Dopant

Frustrated structure of an anticlinic-like smectic-C phase

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