The first bent-core mesogens exhibiting a dimorphism B 7–SmCP A

Pelzl, G.; Schröder, Martin; Dunemann, Ulrike; Diele, Siegmar; Weißflog, W.; Jones, Chris D.; Coleman, David; Clark, Noel A.; Stannarius, Ralf; Li, Jianjun; Das, Bidisa; Grande, S.

doi:10.1039/b316892a

Cited by 57 publications

(32 citation statements)

References 28 publications

(31 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The in-plane modulations observed in freestanding films in this phase for all the compounds studied are characteristic feature of the B 7 phase. Synchrotron studies confirmed that it is the same variant as previously described [20] and may differ from that reported for other compounds [7,23]. The existence of two variants of the B 7 phase has already been mentioned [23].…”

supporting

confidence: 77%

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

Novotná¹,

Hamplová²,

Kašpar³

et al. 2005

Liquid Crystals

Self Cite

View full text Add to dashboard Cite

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.

show abstract

supporting

confidence: 77%

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

Novotná¹,

Hamplová²,

Kašpar³

et al. 2005

Liquid Crystals

Self Cite

View full text Add to dashboard Cite

show abstract

“…[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%

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

et al. 2015

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…[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. [50][51][52][53][54][55] By contrast, different mechanisms, such as the twisting power induced by an offset to the macroscopic polarization and the construction of an enantiomorphoic structure by tilting of molecules with respect to the layer normal, have also been proposed.…”

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

View full text Add to dashboard Cite

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.

show abstract

The first bent-core mesogens exhibiting a dimorphism B 7–SmCP A

Cited by 57 publications

References 28 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

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

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

Contact Info

Product

Resources

About

The first bent-core mesogens exhibiting a dimorphism B 7–SmCP A

Cited by 57 publications

References 28 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

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

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

Contact Info

Product

Resources

About

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

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