Stereochemical rules govern the soft self‐assembly of achiral compounds: Understanding the heliconical liquid crystalline phases of bent‐core mesogens
A. Lehmann,Mohamed Alaasar,Mohamed Alaasar,Marco Poppe,Silvio Poppe,Marko Prehm,Mamatha Nagaraj,S. P. Sreenilayam,Yuri P. Panarin,Jagdish K. Vij,Carsten Tschierske +10 more
TLDR
One is the layer chirality, resulting from the combination of tilt and polar order, and the other one is the helical twist evolving between the layers, providing an alternative non‐chiral way for the transition from anticlinic to synclinic tilt.Abstract:
A series of bent-shaped 4-cyanoresorcinol bisterephthalates is reported. Some of these achiral compounds spontaneously form a short-pitch heliconical lamellar liquid-crystalline phase with incommensurate 3-layer pitch and the helix axis parallel to the layer normal. It is observed at the paraelectric-(anti)ferroelectric transition, if it coincides with the transition from random to uniform tilt and with the transition from anticlinic to synclinic tilt correlation of the molecules in the layers of the developing tilted smectic phase. For compounds with long chains the heliconical phase is only field-induced, but once formed it is stable in a distinct temperature range, even after switching off the field. The presence of the helix changes the phase properties and the switching mechanism from the naturally preferred rotation around the molecular long axis, which reverses the chirality, to a precession on a cone, which retains the chirality. These observations are explained by diastereomeric relations between two coexisting modes of superstructural chirality. One is the layer chirality, resulting from the combination of tilt and polar order, and the other one is the helical twist evolving between the layers. At lower temperature the helical structure is replaced by a non-tilted and ferreoelectric switching lamellar phase, providing an alternative non-chiral way for the transition from anticlinic to synclinic tilt.read more
Citations
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Heliconical smectic phases formed by achiral molecules
Jordan P. Abberley,Ross Killah,Rebecca Walker,John Storey,Corrie T. Imrie,Mirosław Salamończyk,Mirosław Salamończyk,Chenhui Zhu,Ewa Gorecka,Damian Pociecha +9 more
TL;DR: A series of achiral asymmetric dimers with an odd number of atoms in the spacer are reported, which form twisted structures in nematic as well as in lamellar phases, and the short-pitch helical structure in the smectic phases is confirmed by resonant X-ray measurements.
Journal ArticleDOI
Supramolecular Chirality Synchronization in Thin Films of Plasmonic Nanocomposites.
Piotr Szustakiewicz,Natalia Kowalska,Dorota Grzelak,Tetsuya Narushima,Monika Gora,Maciej Baginski,Damian Pociecha,Hiromi Okamoto,Luis M. Liz-Marzán,Wiktor Lewandowski +9 more
TL;DR: A rapid CD imaging technique based on the use of polarized light optical microscopy, which enabled probing the CD signal with micrometer-scale resolution, despite of linear dichroism and birefringence in the sample is developed.
Journal ArticleDOI
Mirror Symmetry Breaking in Liquids and Their Impact on the Development of Homochirality in Abiogenesis: Emerging Proto-RNA as Source of Biochirality?
TL;DR: A model is hypothesized, which assumes the emergence of uniform chirality by chiralities synchronization in dynamic “helical network fluids” followed by polymerization, fixing the chiral and leading to proto-RNA formation in a single process.
Journal ArticleDOI
Distinct twist-bend nematic phase behaviors associated with the ester-linkage direction of thioether-linked liquid crystal dimers
TL;DR: In this article, the twist-bend nematic phase (NTB) is observed in fluidic liquid crystal (LC) phases, which possesses a heliconical structure with a pitch ranging from several to tens of nanometers.
Journal ArticleDOI
Phase behaviors of classic liquid crystal dimers and trimers: Alternate induction of smectic and twist-bend nematic phases depending on spacer parity for liquid crystal trimers
TL;DR: In this article, a series of classic LC trimer homologs, namely 4,4′-bis[ω-(4-cyanobiphenyl-4-yloxy)alkoxy]bipenyls (CBOnOBOnOCB; n = 4−11), was synthesized, and their phase transitions and mesophase structures were evaluated in detail, to reinvestigate their elusive monotropic mesophases.
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