Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism

Abstract

Long-range global chirality is confirmed in the twist-bend nematic phase of bent dimers using circular dichroism spectroscopy. The phase absorbs left and right circularly polarized light differently, confirming its helical rather than wavy character.

Methylene- and thioether-linked cyanobiphenyl-based liquid crystal dimers CBnSCB exhibiting room temperature twist-bend nematic phases and glasses

“…In contrast, a macroscopic chirality was detected in the N TB phase of CB7CB by using circular dichroism spectroscopy. 33 Scanning electron microscopy observations of the photo-crosslinked samples of the N TB phase revealed a helical organization of the nanostructures. [34][35][36] In addition to the N TB phase, other structurally associated mesophases, such as heliconical smectic (Sm) phases based on bent-core molecules 37,38 and bent LC dimers, 39,40 the twist grain-boundary-twistbend nematic phase, 41 and the splay-bend N (N SB ) phase electrically induced from the N TB phase [42][43][44] have been experimentally verified.…”

Distinct twist-bend nematic phase behaviors associated with the ester-linkage direction of thioether-linked liquid crystal dimers

“…[15][16][17] Macroscopic chirality of the N TB phase was verified using circular dichroism spectroscopy. 18 Several techniques, including electro-optical measurements, 19 freeze-fracture transmission electron microscopy, 20,21 and resonant soft, hard, and tender X-ray scattering measurements, [22][23][24][25][26][27] suggest that the helical pitch of an N TB phase formed by several molecules is B10 nm, which is significantly shorter than the pitch of a typical chiral N phase or cholesteric phase exhibiting a helicoidal helix (generally hundreds of nanometers). Materials that exhibit the N TB phase have been employed for various LC applications, such as wavelength-tunable selective light reflection [28][29][30][31] and optical memory 32 devices, LC physical gels, 33 photo-switchable viscoelastic bodies, 34 and photoalignment technology.…”

Supramolecular Chirality Synchronization in Thin Films of Plasmonic Nanocomposites

“…In this context, the phenomenon of chirality synchronization in liquid crystal thin films, in which achiral organic molecules break the mirror symmetry by cooperative locking at a given chiral state, seems particularly appealing. One of the most prominent cases of chiral synchronization is related to selected bent-core liquid crystalline compounds , that are able to form helical nanofilament (HNF) phases. , At a phase transition into the LC state, nucleation points adopt a certain chiral symmetry, which then propagates through the growth of a domain . The final state is a conglomerate structure made of domains with both left and right handedness.…”