The Chiral Twist‐Bend Nematic Phase (N*_TB)

Abstract

The twist‐bend nematic, NTB, phase has been observed for chiral materials in which chirality is introduced through a branched 2‐methylbutyl terminal tail. The chiral twist‐bend nematic phase, N*TB, is completely miscible with the NTB phase of the standard achiral material, CB6OCB. The N*TB phase exhibits optical textures with lower birefringence than those observed for the achiral NTB phase, suggesting an additional mechanism of averaging molecular orientations. The N*−N*TB transition temperatures for the chiral materials are higher than the NTB−N transition temperatures seen for the corresponding racemic materials. This suggests the double degeneracy of helical twist sense in the NnormalTnormalB* phase is removed by the intrinsic molecular chirality. A square lattice pattern is observed in the N* phase over a temperature range of several degrees above the N*TB–N phase transition, which may be attributed to a non‐monotonic dependence of the bend elastic constant.

Ether‐ and Thioether‐Linked Naphthalene‐Based Liquid‐Crystal Dimers: Influence of Chalcogen Linkage and Mesogenic‐Arm Symmetry on the Incidence and Stability of the Twist–Bend Nematic Phase

“…[17] Besides liquid-crystal dimers, the N TB phase has also been observedi nb ent-core molecules, [5,[18][19][20] oligomers, [21][22][23][24][25] and polymers. [3,4,26] Although the majority of twist-bend nematogens developeds of ar are achiral,t here have been af ew reports on formation of the N TB phase based on chiral bentshaped molecules,i nw hicht he chirality is located in the mesogenic-arm core, [27,28] terminal chain, [29] or spacer. [30] The N TB liquid crystalsh ave successfully been employedf or photonic applications.…”

Twist-Bend Nematogenic Supramolecular Dimers and Trimers Formed by Hydrogen Bonding

“…As this induction of chirality is spontaneous, there exists an equal probability of the formation of either handedness of the helix, and hence, the N TB phase consists of doubly degenerate locally chiral domains of opposite handedness giving a globally achiral phase. However, the presence of intrinsic molecular chirality removes this degeneracy and the chiral N TB phase is formed [5]. In his seminal work, Dozov also predicted the formation of heliconical smectic phases [3] and examples of these have recently been reported [6][7][8].…”

Nematogenic Laterally Substituted Supramolecular H-Bonded Complexes Based on Flexible Core

“…H-bonding interactions are power tools for forming and inducing new mesophases [7][8][9][10][11][12][13]. Thus, HBSMCs have been attracting considerable attention based on the preparation of new geometrical molecules, as well as the mesomorphic characterizations and the structure-property relationships of them [1][2][3][4][5][6][14][15][16][17][18].…”