Polarization splay as the origin of modulation in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>B</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>B</mml:mi><mml:mn>7</mml:mn></mml:mrow></mml:math>smectic phases of bent-core molecules

Coleman, David; Jones, Chris D.; Nakata, Michi; Clark, Noel A.; Walba, David M.; Weißflog, W.; Fodor‐Csorba, Katalin; Watanabe, Junji; Novotná, Vladimı́ra; Hamplová, Věra

doi:10.1103/physreve.77.021703

Cited by 40 publications

(39 citation statements)

References 18 publications

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“…The multiple-step "cliffs" show the layer undulation propagating through many layers without changing the smectic structure. This kind of layer undulation has so far been observed in the ripple phase of phospholipids (39) and in the B1 and B7 phases of bent-core LCs (40)(41)(42). This observation indicates that engineered supercharged polypeptides are able to self-assemble into ordered-layer TLC structures in the absence of any solvent, although they did not exhibit a typical α-helical or β-sheet secondary structure.…”

Section: Resultsmentioning

confidence: 61%

Thermotropic liquid crystals from biomacromolecules

Li¹,

Chen

Marcozzi³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Complexation of biomacromolecules (e.g., nucleic acids, proteins, or viruses) with surfactants containing flexible alkyl tails, followed by dehydration, is shown to be a simple generic method for the production of thermotropic liquid crystals. The anhydrous smectic phases that result exhibit biomacromolecular sublayers intercalated between aliphatic hydrocarbon sublayers at or near room temperature. Both this and low transition temperatures to other phases enable the study and application of thermotropic liquid crystal phase behavior without thermal degradation of the biomolecular components.L iquid crystals (LCs) play an important role in biology because their essential characteristic, the combination of order and mobility, is a basic requirement for self-organization and structure formation in living systems (1-3). Thus, it is not surprising that the study of LCs emerged as a scientific discipline in part from biology and from the study of myelin figures, lipids, and cell membranes (4). These and the LC phases formed from many other biomolecules, including nucleic acids (5, 6), proteins (7,8), and viruses (9, 10), are classified as lyotropic, the general term applied to LC structures formed in water and stabilized by the distinctly biological theme of amphiphilic partitioning of hydrophilic and hydrophobic molecular components into separate domains. However, the principal thrust and achievement of the study of LCs has been in the science and application of thermotropic materials, structures, and phases in which molecules that are only weakly amphiphilic exhibit LC ordering by virtue of their steric molecular shape, flexibility, and/or weak intermolecular interactions [e.g., van der Waals and dipolar forces (11)]. These characteristics enable thermotropic LCs (TLCs) to adopt a wide variety of exotic phases and to exhibit dramatic and useful responses to external forces, including, for example, the electro-optic effects that have led to LC displays and the portable computing revolution. This general distinction between lyotropic LCs and TLCs suggests there may be interesting possibilities in the development of biomolecular or bioinspired LC systems in which the importance of amphiphilicity is reduced and the LC phases obtained are more thermotropic in nature. Such biological TLC materials are very appealing for several reasons. Most biomacromolecules were extensively characterized in aqueous environments, but in TLC phases, their solvent-free properties and functions could be investigated in a state in which no or only traces of water are present. Water exhibits a high dielectric constant and has the ability to form hydrogen bonds, greatly influencing the structure and functions of biomacromolecules or compromising electronic properties such as charge transport (12-15). Indeed, anhydrous TLC systems containing glycolipids (16-19), ferritin (20), and polylysine have been reported (21-23). However, a general approach to fabricating TLCs based on nucleic acids, polypeptides, proteins, and protein assemblies of larg...

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Section: Resultsmentioning

confidence: 61%

Thermotropic liquid crystals from biomacromolecules

Li¹,

Chen

Marcozzi³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…[9][10][11][12][13][14] The amazing optical B7 textures attracted an intense research that lead to many important findings. [7][8][9]13,[15][16][17][18][19][20][21] Small angle X-ray scattering (SAXS) [7,16,19] studies revealed a number peaks [16,19] that can be indexed by a slightly oblique monoclinic 2D unit cell with a~3-5 nm and b~8-20 nm periodicities. This can be interpreted either as a columnar [19,21] or as an undulated smectic layer structure [16]; in the columnar model, the layers break into ribbons with half layer steps, whereas the undulated layers are continuous.…”

Section: Introductionmentioning

confidence: 99%

“…This can be interpreted either as a columnar [19,21] or as an undulated smectic layer structure [16]; in the columnar model, the layers break into ribbons with half layer steps, whereas the undulated layers are continuous. [21] Direct visualisation of nanostructures requires transmission electron microscopy (TEM). Freeze fracture TEM (FF-TEM) technique uses a replica created on the fracture surface of a few micron thick film or filament quenched by liquid nitrogen, and measures the reflected electron intensity, therefore provides information on the surface of a bulk material.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale structures of polarisation-modulated bent-core materials in thin films

et al. 2015

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We present small angle X-ray and cryogenic transmission electron microscopy (cryo-TEM) studies of three nitrosubstituted (n-OPIMB-NO 2 , n = 7, 9 and16) bent-core liquid crystals (LCs) that form peculiar optical patterns known as B7 textures. Small angle X-ray scattering studies show two periodicities between a~3.4-4.7 nm and b X~9 -16 nm. Cryo-TEM images of about 100 nm thick films do not show the a-periodicity, but only periodicities b T that are about 1 nm smaller than b X measured in bulk by X-ray. Additionally, an intensity modulation with a period c~100-200 nm is observed. These observations can be explained by a B1-type structure, where there are half-layer step discontinuities at the boundaries of the splay domains, and where the molecules are everywhere normal to the substrate.

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“…It is characterized by a smectic order of the tilted molecules, displaying polar order within the smectic layers described by the director p(x,y), orthogonal to the c-director. Compared to a nonmodulated SmCP [28] phase, the layers in the polarization-modulated SmCP U A phase are undulated and this undulation is coupled to the variation of the director field, resulting in a periodic splay deformation of p in the bulk [27,29]. Here we present a study of the formation of the labyrinthine structure in freely suspended films of SmCP U A and discuss its relation to the polarization-modulated structure of the phase.…”

Section: Introductionmentioning

confidence: 96%

“…In this paper, we show another example of the labyrinthine instability in freely suspended films of a nonintercalated polarizationmodulated layer undulated tilted smectic phase. This phase belongs to a group of B 7 mesophases of bent-core mesogens and designated as SmCP U A [27]. It is characterized by a smectic order of the tilted molecules, displaying polar order within the smectic layers described by the director p(x,y), orthogonal to the c-director.…”

Section: Introductionmentioning

confidence: 99%

Labyrinthine instability in freely suspended films of a polarization-modulated smectic phase

et al. 2013

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We report on fingering and labyrinthine instabilities of the layer dislocation lines in freely suspended polar liquid-crystalline films. These polar fingerlike and labyrinth structures reversibly form upon a transition into a modulated phase. External electric fields of several kV/m applied in the film plane can reversibly influence the formation of the finger textures. We show that the labyrinthine pattern is intrinsically related to regular splay deformations of the polarization.

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Polarization splay as the origin of modulation in theB1andB7smectic phases of bent-core molecules

Cited by 40 publications

References 18 publications

Thermotropic liquid crystals from biomacromolecules

Thermotropic liquid crystals from biomacromolecules

Nanoscale structures of polarisation-modulated bent-core materials in thin films

Labyrinthine instability in freely suspended films of a polarization-modulated smectic phase

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