Intrinsic chiral domains enantioselectively segregated from twisted nematic cells of bent‐core mesogens

Choi, Suk–Won; Kang, Sungmin; Takanishi, Yoichi; Ishikawa, Ken; Watanabe, Junji; Takezoe, Hideo

doi:10.1002/chir.20358

Cited by 27 publications

(9 citation statements)

References 34 publications

(47 reference statements)

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“…(This CD spectrum does not change on reversing the direction of light propagation). These CD values are considerably lower than those usually found in the DC phase [37] and no peak is observed in the measured wavelength range. The positive CD values in the ground state of the DC phase indicate that there already exists a bias towards one handedness over the other.…”

Section: Optical Experimentscontrasting

confidence: 75%

Unusual electric-field-induced transformations in the dark conglomerate phase of a bent-core liquid crystal

et al. 2014

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Unusual behaviour of the dark conglomerate (DC) phase seen in an oxadiazole-based achiral bent-core liquid crystal, which has not previously been reported for the DC phase of other liquid crystals, is described. Under polarizing optical microscopy, we see no domains of opposite handedness in the ground state of the DC phase. However, it shows unusual transformations when an electric field is applied to the system: On increasing the electric field, at first the domains of opposite handedness become visible and then they grow in size and slowly the sample transforms to a monochiral or single handed form which is followed by a nonchiral state at very high fields. The threshold electric fields required to achieve these changes are temperature dependent and the transformations are seen irrespective of the frequency of the applied electric field (100 Hz to 5 kHz), type of the waveform (sine, square and triangular) and the thickness (1.5 µm to 15 µm) or the geometry (planar and twisted) of the device used. Further, there is no field-induced high birefringence texture observed even though sufficiently large electric field (~22 V/µm) has been applied across the devices. The nature of the behaviour is investigated by various techniques such as optical microscopy, conoscopy, circular dichroic and Raman spectroscopies, electro-optics and dielectric spectroscopy. The possible physical phenomena behind these changes are discussed in detail.

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Section: Optical Experimentscontrasting

confidence: 75%

Unusual electric-field-induced transformations in the dark conglomerate phase of a bent-core liquid crystal

et al. 2014

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“…In fact then, they observed a nematic phase which exhibited the properties of a conglomerate. The enantioselective segregation has been obtained in the smectic and nematics phases of other banana oxadiazoles, without introducing any chiral species, by a Japanese group [30]. This sort of segregation is rather important for drugs, because the stereoisomers of chiral drugs often exhibit pronounced differences in their properties, so pronounced that it is necessary to study each stereoisomer separately [31].…”

Section: Enantioselective Segregation and Drugsmentioning

confidence: 99%

Some Features of Liquid Crystalline Oxadiazoles

Sparavigna¹

2013

ijSciences

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Abstract:We propose a survey of some features of those oxadiazole compounds which are mesogenic, that is, which are displaying liquid crystalline properties induced by their rod-or disk-like molecules. We will see that they can have bend-shaped molecules too, creating biaxial phases, and other interesting peculiarities in the nematic and smectic phases. With large electric dipoles and luminescent properties, these materials are also very appealing for technological applications.

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“…In fact then, they observed a nematic phase exhibiting the properties of a conglomerate. Enantioselective segregation has been obtained in the smectic and nematics phases of other banana oxadiazoles, without introducing any chiral species, by a Japanese group [28].…”

Section: Oxadiazoles For Electroluminescencementioning

confidence: 99%