Biaxial smectic A phase in homologous series of compounds composed of highly polar unsymmetrically substituted bent-core molecules

Sadashiva, B. K.; Reddy, R. Amaranatha; Pratibha, R.; Madhusudana, N. V.

doi:10.1039/b109546c

Cited by 83 publications

(63 citation statements)

References 24 publications

(33 reference statements)

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“…There is also a claim for the observation of a biaxial SmA phase in an oxadiazole derivative [18], where the constituent molecules are boomerang in shape. Recently we have reported [19,20] the synthesis and characterization of the mesophases exhibited by several unsymmetrical compounds composed of strongly polar molecules. Many of these exhibit the biaxial SmA phase.…”

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confidence: 99%

A polar biaxial smectic A phase in new unsymmetrical compounds composed of bent-core molecules

Murthy

Sadashiva

2004

Liquid Crystals

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The synthesis and liquid crystalline properties of several new compounds unsymmetrically substituted about two different central phenyl rings are reported. All the compounds contain a strongly polar terminal cyano/nitro substituent. Some of the nitro-substituted compounds derived from 3-hydroxybenzoic acid show a transition from the partial bilayer uniaxial smectic A (SmA d ) phase to a polar partial bilayer biaxial smectic A (SmA d P A ) phase. The analogous cyano-substituted derivatives exhibit only a SmA d phase. However, compounds containing a 4-cyanobiphenyl moiety in the terminal position and derived from 1,3-dihydroxybenzene show the SmA d -SmA d P A transition. The mesophases were characterized using polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction studies, conoscopic examination and miscibility studies.

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A polar biaxial smectic A phase in new unsymmetrical compounds composed of bent-core molecules

Murthy

Sadashiva

2004

Liquid Crystals

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“…Essentially two different types of biaxial smectic phases were discovered: polar biaxial (Sm-C PA ) [ 12] in 2001 and nonpolar biaxial (Sm-A db ) [13] [here d stands for double layer (interdigitated) and b for biaxial] in 2002. Sm-C PA is composed of orthogonal polar smectic layers with antiferroelectric structure, i.e., alternating polar directions in the neighboring layers are antiferroelectrically arranged.…”

Section: Introductionmentioning

confidence: 99%

Biaxial order parameter in the homologous series of orthogonal bent-core smectic liquid crystals

Sreenilayam¹,

Panarin

Vij

et al. 2013

Phys. Rev. E

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This version is available at https://strathprints.strath.ac.uk/47177/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.PHYSICAL REVIEW E 88, 012504 (2013) Biaxial order parameter in the homologous series of orthogonal bent-core smectic liquid crystals The fundamental parameter of the uniaxial liquid crystalline state that governs nearly all of its physical properties is the primary orientational order parameter (S) for the long axes of molecules with respect to the director. The biaxial liquid crystals (LCs) possess biaxial order parameters depending on the phase symmetry of the system. In this paper we show that in the first approximation a biaxial orthogonal smectic phase can be described by two primary order parameters: S for the long axes and C for the ordering of the short axes of molecules. The temperature dependencies of S and C are obtained by the Haller's extrapolation technique through measurements of the optical birefringence and biaxiality on a nontilted polar antiferroelectric (Sm-AP A ) phase of a homologous series of LCs built from the bent-core achiral molecules. For such a biaxial smectic phase both S and C, particularly the temperature dependency of the latter, are being experimentally determined. Results show that S in the orthogonal smectic phase composed of bent cores is higher than in Sm-A calamatic LCs and C is also significantly large.

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“…This relationship has also been reported for monomeric terminally polar substituted banana-shaped compounds. [7,65,66] The sequence of two nematic phases, a (conventional) nematic and a twist bent nematic phase, is a topic of the present work. Definite connections between the appearance of the NTB phase and the chemical constitution of the molecules are unknown.…”

Section: Discussionmentioning

confidence: 99%

Banana-calamitic Dimers: Further Variations of the Bent-core Mesogenic Unit

et al. 2014

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Banana-calamitic dimers are a topic in the field of bent-core mesogens. New materials were prepared by chemical variations at the bent-core fragment that is by a cyano group terminally attached to the bent-core fragment, by lateral substitution with a chlorine atom and methyl group, respectively, and by increasing the number of phenyl rings from five to six. The bent-core and the calamitic mesogenic moieties are connected by aliphatic spacers of different length. The materials were investigated by optical microscopy, DSC, X-ray diffraction studies and electro-optical measurements. This way nematic, smectic and various types of polar columnar phases have been characterized. The low temperature phase in a sequence of two nematic phases exhibiting different properties can be classified as a nematic twist-bend phase. Such NTB phases are only formed if a bend exists along the molecular long axes. This prerequisite can be doubly achieved in banana-calamitic dimers: by the intrinsic bend of one of the mesogenic fragments and by an odd-numbered spacer.

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Biaxial smectic A phase in homologous series of compounds composed of highly polar unsymmetrically substituted bent-core molecules

Cited by 83 publications

References 24 publications

A polar biaxial smectic A phase in new unsymmetrical compounds composed of bent-core molecules

A polar biaxial smectic A phase in new unsymmetrical compounds composed of bent-core molecules

Biaxial order parameter in the homologous series of orthogonal bent-core smectic liquid crystals

Banana-calamitic Dimers: Further Variations of the Bent-core Mesogenic Unit

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