Supermolecular stereochemistry in ferroelectric liquid crystals

Walba, David M.; Krblova, Eva; Shao, Renfan; Maclennan, Joseph E.; Link, Darren R.; Glaser, Matthew A.; Clark, Noel A.

doi:10.1002/1099-1395(200012)13:12<830::aid-poc327>3.0.co;2-j

Cited by 20 publications

(18 citation statements)

References 17 publications

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“…Three models could satisfy such an observation. According to the model described in [2], the field-free structure would be the chiral structure (SmC A P A ), while under the high electric field the racemic structure (SmC A P F ) occurs. This model should be disregarded as it involves the same birefringence in both field and field-free structures in …”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Liquid crystals composed of banana-like (bent-core) molecules have become an important subfield in the investigation of mesogenic compounds [1][2][3][4][5][6]. Chiral polar phases can exist even when the banana-like molecules are non-chiral.…”

Section: Introductionmentioning

confidence: 99%

“…Chiral polar phases can exist even when the banana-like molecules are non-chiral. Then the bent molecules packed in layers are tilted with respect to the layer normal [2]. Polarization switching originates from ordering of molecular dipoles within smectic layers by an external electric field.…”

Section: Introductionmentioning

confidence: 99%

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The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

Novotná¹,

Hamplová²,

Kašpar³

et al. 2005

Liquid Crystals

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2005) The B 2 -B 7 phase transition in symmetrical bent-shaped mesogens with methoxy substitution, Liquid Crystals, 32:8, 967-975, New mesogens composed of achiral bent molecules with thermally stable ester linkages, and laterally substituted by a methoxy group symmetrically near the central benzene ring, were synthesized. Texture, calorimetric, electro-optical, X-ray and dielectric measurements were performed. In most of studied compounds the antiferroelectric B 2 phase was found on cooling from the isotropic phase, followed by the B 7 phase at lower temperatures. Undulation of layers in the B 7 phase was confirmed by precise synchrotron studies.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

Novotná¹,

Hamplová²,

Kašpar³

et al. 2005

Liquid Crystals

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“…shaped molecules can be observed in their unique mesophases such as B 2 phase with electro-optical switchable property (the smectic layered chirality induced by the existence of the polar direction and the tilting molecular director with respect to the layer normal) [36][37][38][39][40] , B 4 phase with opposite optical activity (the different chiral domains formed from the helical morphology which is similar to the twist grain boundary phase), [41][42][43][44] and B 7 phase with macroscopic spiral and more complicated textures. [45][46][47][48][49] Watanabe and co-workers suggested that the asymmetric twisting conformation which is resulted from the ester linkage groups connecting the central phenyl ring with the side wings seems to be one of the origins for the formation of the helical morphology.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Superstructures with Helical Sense in Self‐Assembled Achiral Banana‐Shaped Liquid Crystalline Molecules

Lin

et al. 2008

Adv Funct Materials

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The self‐assembly of 1,3‐phenylene bis[4‐(4‐n‐heptyloxybenzoyloxy)‐benzoates] (BC7) is studied to examine the formation of helical morphologies from achiral banana‐shaped liquid crystal molecules at different self‐assembling levels. Various hierarchical superstructures including flat‐elongated lamellar crystal, left‐ and right‐handed helical ribbons, and tubular texture are observed while the BC7 molecules self‐assemble in THF/H2O solution. By contrast, only plate‐like morphology is observed in the self‐assembly of achiral linear shaped 1,4‐phenylene bis[4‐(4‐n‐heptyloxybenzoyloxy)‐benzoates] (LC7) molecules, indicating that the chirality of the self‐assembled texture is strongly dependent upon the molecular geometry of the achiral molecules. The formation of the helical superstructures, namely hierarchical chirality, is attributed to the conformational chirality from the achiral banana‐shaped liquid crystalline molecules, as evidenced by significant optical activity in time‐resolved circular dichroism experiments. Selective area electron diffraction is performed to examine the structural packing of the hierarchical superstructures. As observed, the molecular disposition of the lamellar crystal is identical to that of the helical superstructure. Also, the diffraction patterns of the helical superstructures appeared arc‐like patterns consisting of a series of reflections, suggesting that the helical morphology resulted from the curving of the lamellar crystals through a twisting and bending mechanism. Consequently, the model of molecular disposition in the self‐assembled helical superstructures from the achiral banana‐shaped molecules is proposed. The morphological evolution in this study may provide further understanding with respect to the chiral information transfer mechanism from specific molecular geometry to hierarchical chirality in the achiral banana‐shaped molecules.

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“…This phase also exhibits helical nuclei and a domain morphology quite similar to the original B 7 phase [9,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The B 7 9 phase has been reported for bent mesogens with quite different structures.…”

mentioning

confidence: 99%

Preliminary communication Helical superstructures in a novel smectic mesophase formed by achiral banana‐shaped molecules

et al. 2006

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Supermolecular stereochemistry in ferroelectric liquid crystals

Cited by 20 publications

References 17 publications

The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

Hierarchical Superstructures with Helical Sense in Self‐Assembled Achiral Banana‐Shaped Liquid Crystalline Molecules

Preliminary communication Helical superstructures in a novel smectic mesophase formed by achiral banana‐shaped molecules

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Supermolecular stereochemistry in ferroelectric liquid crystals

Cited by 20 publications

References 17 publications

The B2–B7phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

The B2–B7phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

Hierarchical Superstructures with Helical Sense in Self‐Assembled Achiral Banana‐Shaped Liquid Crystalline Molecules

Preliminary communication Helical superstructures in a novel smectic mesophase formed by achiral banana‐shaped molecules

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The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution

The B₂–B₇phase transition in symmetrical bent‐shaped mesogens with methoxy substitution