Bent-core liquid crystals in the route to functional materials

Etxebarría, J.; Ros, M. Blanca

doi:10.1039/b803507e

Cited by 183 publications

(103 citation statements)

References 97 publications

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“…We find the optimal value of the curvature radius to be around α ≈ π/10 when the modulated-nematic phase occurs at the lowest packing density. This finding might be particularly useful in developing novel functional optical materials based on organic bent-core liquid crystals, 77,78 where the formation of polar domains can be used to tune the nonlinear optical properties of the material.…”

Section: Discussionmentioning

confidence: 99%

Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Tavarone

Stark

2015

The Journal of Chemical Physics

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We perform extensive Monte Carlo simulations of a two-dimensional bent hard-needle model in both its chiral zig-zag and its achiral bow-shape configurations and present their phase diagrams. We find evidence for a variety of stable phases: isotropic, quasi-nematic, smectic-C, anti-ferromorphic smectic-A, and modulated-nematic. This last phase consists of layers formed by supramolecular arches. They create a modulation of the molecular polarity whose period is sensitively controlled by molecular geometry. We identify transition densities using correlation functions together with appropriately defined order parameters and compare them with predictions from Onsager theory. The contribution of the molecular excluded area to deviations from Onsager theory and simple liquid crystal phase morphology is discussed. We demonstrate the isotropic-quasi-nematic transition to be consistent with a Kosterlitz-Thouless disclination unbinding scenario. C 2015 AIP Publishing LLC. [http://dx

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Section: Discussionmentioning

confidence: 99%

Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Tavarone

Stark

2015

The Journal of Chemical Physics

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“…[1][2][3] The formation of chiral smectic phases has been a key feature of achiral, banana-shaped molecules, with spontaneous symmetry breaking originally described in the B2 phase of P-9-OPIMB, also known as NOBOW. [4] The first observation of macroscopic chiral domains, however, was in the B4 phase of P-9-OPIMB homologs, [5] where large left-and right-handed chiral domains were distinguished under decrossed polarizer and analyzer.…”

Section: Introductionmentioning

confidence: 99%

Structure of the B4 Liquid Crystal Phase near a Glass Surface

Chen¹,

Heberling²,

Nakata³

et al. 2011

ChemPhysChem

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The B4 liquid crystal phase of bent-core molecules, a smectic phase of helical nanofilaments, is one of the most complex hierarchical self-assemblies in soft materials. We describe the layer topology of the B4 phase of mesogens in the P-n-OPIMB homologous series near the liquid crystal/glass interface. Freeze-fracture transmission electron microscopy reveals that the twisted layer structure of the bulk is suppressed, the layers instead forming a structure with periodic layer undulations, with the topography depending on the distance from the glass. The surface layer structure is modeled as parabolic focal conic arrays generated by equidistant parabolas whose foci are defect lines along the glass surface. Nucleation and growth of toric focal conics near the glass substrate is also observed. Although the growth of twisted nanofilaments, the usual manifestation of structural chirality in the B4 phase, is suppressed near the surface, the smectic layers are intrinsically chiral, and the helical filaments that form on top of them grow with specific handedness.

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“…During the last decade, spontaneous reflection symmetry breaking has been reported in several fluid LC phases of achiral bent-core molecules, with macroscopic, chiral conglomerate domains and a wide variety of novel structural phenomena involving the interplay of chiral, polar and liquid crystalline order observed in smectic phases of tilted molecules [22][23][24][25][26][27][28][29] . Among the novel phases exhibited by bent-core mesogens, the helical nanofilament (HNF) phase is one of the most fascinating and potentially useful.…”

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confidence: 99%

Diastereomeric liquid crystal domains at the mesoscale

et al. 2015

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In many technologies used to achieve separation of enantiomers, chiral selectors are designed to display differential affinity for the two enantiomers of a chiral compound. Such complexes are diastereomeric, differing in structure and free energy for the two enantiomers and enabling chiral discrimination. Here we present evidence for strong diastereomeric interaction effects at the mesoscale, manifested in chiral liquid crystal guest materials confined in a chiral, nanoporous network of semi-crystalline helical nanofilaments. The nanoporous host is itself an assembly of achiral, bent-core liquid crystal molecules that phase-separate into a conglomerate of 100 micron-scale, helical nanofilament domains that differ in structure only in the handedness of their homogeneous chirality. With the inclusion of a homochiral guest liquid crystal, these enantiomeric domains become diastereomeric, exhibiting unexpected and markedly different mesoscale structures and orientation transitions producing optical effects in which chirality has a dominant role.

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Bent-core liquid crystals in the route to functional materials

Cited by 183 publications

References 97 publications

Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Structure of the B4 Liquid Crystal Phase near a Glass Surface

Diastereomeric liquid crystal domains at the mesoscale

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