B 2 -B 4 Dimorphism in a New Series of Banana-Shaped Mesogens

Nádasi, Hajnalka; Lischka, Ch.; Weißflog, W.; Wirth, I.; Diele, Siegmar; Pelzl, G.; Kresse, H.

doi:10.1080/15421400390225471

Cited by 11 publications

(16 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[24]) is a five-ringed, banana-shaped mesogen derived from isophthalaldehyde. [24]) is a five-ringed, banana-shaped mesogen derived from isophthalaldehyde.…”

Section: Resultsmentioning

confidence: 99%

“…The chemical structure and phase sequence of W624 are shown in Figure 1 a. [24], with one more carbon at each tail) has been studied in detail by Nµdasi et al, which shows two current peaks per half-period of a triangular voltage. The B2 phase of the W624 homologue (compound 2e in ref.…”

Section: Resultsmentioning

confidence: 99%

“…[25] Upon cooling, the B2 phase appears from the isotropic phase with a typical banana-leaf-like texture shown in Figure 2 a and b. [24] Upon further cooling, the texture changes completely and the overall birefringence is very low, as shown in Figure 2 c and d. No left-or right-handed chiral domains can be distinguished in the neat material by decrossing the polarizers, and the phase does not respond to applied electric field. [24], with one more carbon at each tail) has been studied in detail by Nµdasi et al, which shows two current peaks per half-period of a triangular voltage.…”

Section: Resultsmentioning

confidence: 99%

“…W624 (originally reported as compound 2d in ref. [24]) is a five-ringed, banana-shaped mesogen derived from isophthalaldehyde. The chemical structure and phase sequence of W624 are shown in Figure 1 a.…”

Section: Resultsmentioning

confidence: 99%

“…[24], with one more carbon at each tail) has been studied in detail by Nµdasi et al, which shows two current peaks per half-period of a triangular voltage. [24] Upon further cooling, the texture changes completely and the overall birefringence is very low, as shown in Figure 2 c and d. No left-or right-handed chiral domains can be distinguished in the neat material by decrossing the polarizers, and the phase does not respond to applied electric field. There is no further change in the texture when the sample is cooled to room temperature.…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Chiral Isotropic Sponge Phase of Hexatic Smectic Layers of Achiral Molecules

et al. 2013

View full text Add to dashboard Cite

Smectic layers of tilted, bent-core liquid crystals have a tendency to exhibit spontaneous saddle-splay curvature, a mechanical response that relieves the internal strain of the layers. When this tendency is strong enough, the smectic layers form complex, equilibrium, non-planar structures such as the helical nanofilaments in the B4 phase and the disordered focal conics in the chiral dark conglomerate (DC) phase. The DC phase is usually observed on cooling directly from the isotropic phase, with the disordered focal conics analogous to the disordered sponge phase found in lyotropic systems. We report a DC phase observed below a B2 phase that is stable down to room temperature. In mixtures with the calamitic liquid crystal 8CB, the low-temperature DC phase forms a more ordered, bicontinuous structure, resembling the cubic phase observed in the lyotropic systems, which is attributed to the enhanced intralayer ordering of the bent-core molecules in the mixtures.

show abstract

“…[24]) is a five-ringed, banana-shaped mesogen derived from isophthalaldehyde. [24]) is a five-ringed, banana-shaped mesogen derived from isophthalaldehyde.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Chiral Isotropic Sponge Phase of Hexatic Smectic Layers of Achiral Molecules

et al. 2013

View full text Add to dashboard Cite

show abstract

Helical Nano‐crystallite (HNC) Phases: Chirality Synchronization of Achiral Bent‐Core Mesogens in a New Type of Dark Conglomerates

Alaasar

Prehm

Tschierske

2016

Chemistry A European J

View full text Add to dashboard Cite

Spontaneous generation of macroscopic homochirality in soft matter systems by self-assembly of exclusively achiral molecules under achiral conditions is a challenging task with relevance for fundamental scientific research and technological applications. Dark conglomerate phases (DC phases), being optically isotropic mesophases composed of conglomerates of macroscopic chiral domains and formed by some non-chiral bent-core mesogens, represent such a case. Here we report two new series of non-symmetric bent-core molecules capable of forming a new type of mirror symmetry broken DC phases. In the synthesized molecules, a bent 4-bromoresorcinol core is connected to a phenyl benzoate wing and an azobenzene wing with or without additional peripheral fluorine substitution. The self-assembly was investigated by DSC, polarizing microscopy, electro-optical studies and XRD. Chiral and apparently achiral DC phases were observed besides distinct types of lamellar liquid crystalline phases with different degree of polar order, allowing the investigation of the transition from smectic to DC phases. This indicates a process in which increased packing density at first gives rise to restricted rotation and thus to growing polar order, which then leads to chirality synchronization, layer frustration and nano-scale crystallization. Topological constraints arising from the twisted packing of helical conformers in lamellar crystals is proposed to lead to amorphous solids composed of helical nano-crystallites with short coherence length (HNC phases). This is considered as a third major type of DC phases, distinct from the previously known liquid crystalline sponge phases and the helical nano-filament phases (HNF phases). Guidelines for the molecular design of new materials capable of self-assembly into these three types of DC phases are proposed.

show abstract

Nanoconfinement of the Low‐Temperature Dark Conglomerate: Structural Control from Focal Conics to Helical Nanofilaments

Foley

Park

Yang

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

The helical nanofilament (HNF) and low‐temperature dark conglomerate (DC) liquid‐crystal (LC) phases of bent‐core molecules show the same local layer structure but present different bulk morphologies. The DC phase is characterized by the formation of nanoscale toric focal conics, whereas the HNF phase is constructed of bundles of twisted layers. Although the local layer structure is similar in both phases, materials that form these phases tend to form one morphology in preference to the other. Targeted control of the nanostructures would provide pathways to potential applications and insight into how conditions drive a specific phase formation. Here, W624, a compound known to form the DC phase is confined in nanometer scale channels of porous anodized aluminum oxide (AAO) membranes. Within each nanochannel, the DC phase is suppressed forming the HNF structure instead, indicating the nanoscale spatial limitation can control the phase structure of the DC phase.

show abstract

B 2 -B 4 Dimorphism in a New Series of Banana-Shaped Mesogens

Cited by 11 publications

References 16 publications

Chiral Isotropic Sponge Phase of Hexatic Smectic Layers of Achiral Molecules

Chiral Isotropic Sponge Phase of Hexatic Smectic Layers of Achiral Molecules

Helical Nano‐crystallite (HNC) Phases: Chirality Synchronization of Achiral Bent‐Core Mesogens in a New Type of Dark Conglomerates

Nanoconfinement of the Low‐Temperature Dark Conglomerate: Structural Control from Focal Conics to Helical Nanofilaments

Contact Info

Product

Resources

About