The twist bend nematic: a case of mistaken identity

  title={The twist bend nematic: a case of mistaken identity},
  author={Edward T. Samulski and Alexandros G. Vanakaras and Demetri J. Photinos},
  journal={Liquid Crystals},
  pages={2092 - 2097}
ABSTRACT We review the physics underlying Meyer’s conjecture of how macroscopic-scale twist and bend conspire within the Frank-Oseen elasticity theory of nematics to create a heliconical arrangement of the uniaxial, apolar nematic director, the so-called ‘twist bend nematic’ NTB. We show that since 2011 a second, lower-temperature nematic phase observed in odd methylene-linked cyanobiphenyl dimers discovered by Toriumi and called NX, has been incorrectly identified as NTB. Moreover, as more… 
Phase diagram of a model melt of bent--core molecules
ABSTRACT The Landau theory of phase transitions with single-order parameter (second rank alignment tensor) has been applied to study the formation of modulated nematic phases in a melt of the
A generalized density-modulated twist-splay-bend phase of banana-shaped particles
It is shown that the coupling between polar order and bend deformations drives the formation of modulated phases in systems of curved rods, and that splay distortions are always accompanied by periodic density modulations due to the coupling of the particle curvature with the non-uniform curvature of the splayed director field.
Thioether-linked azobenzene-based liquid crystal dimers exhibiting the twist-bend nematic phase over a wide temperature range
ABSTRACT Two homologous series of sulfur-containing thioether-linked 4-cyanoazobenzene-based liquid crystal (LC) dimers were developed: a symmetric series based on 4-cyanoazobenzene arms
'Setting things straight' by twisting and bending?
We explain the origins of the controversy about the classification of the $N_X$ phase observed in cyanobiphenyl dimers and why it is a polar twisted phase, an entirely new kind of nematic.
All Structures Great and Small: Nanoscale Modulations in Nematic Liquid Crystals
It is shown that the low temperature nematic phase (NX), first observed in symmetric mesogenic dimers of the CB-n-CB series with an odd number of methylene spacers, is unrelated to any of the elastic deformations stipulated by the continuum elasticity theory of nematics, and presented a coherent formulation of one-dimensionally modulated nematics based on the Frank–Oseen elasticity Theory.
Methylene- and thioether-linked cyanobiphenyl-based liquid crystal dimers CBnSCB exhibiting room temperature twist-bend nematic phases and glasses
A homologous series of methylene- and thioether-linked cyanobiphenyl-based liquid crystal dimers, CBnSCB, was developed and found to exhibit stable twist-bend nematic (NTB) phases, which undergo
Molecular biaxiality determines the helical structure - infrared measurements of the molecular order in the nematic twist-bend phase of difluoro terphenyl dimer.
The orientational order, distinctly reverses its monotonic trend of increase to decrease at the transition temperature, from the uniaxial nematic to the twist-bend nematic phase as result of the director tilt in latter/(twist- bend) phase.
The interplay between spatial and heliconical orientational order in twist-bend nematic materials.
This work presents hard and resonant tender X-ray scattering studies of two novel sulfur containing dimer materials and finds that at the transition to the NTB phase the positional correlation length drops, which indicates a layered (SmATB) phase wherein the rigid units of the dimers are tilted with respect to the smectic layer normal.
Setting things straight in ‘The twist-bend nematic: a case of mistaken identity’
ABSTRACT Stimulated by the paper that precedes this, our aim is to correct an error made concerning the twist-bend nematic phase and to place its development, both theoretical and experimental, in


Elastic continuum theory: towards understanding of the twist-bend nematic phases.
The twist-bend nematic phase, N_{TB}, may be viewed as a heliconical molecular arrangement in which the director n precesses uniformly about an extra director field, t. It corresponds to a nematic
Molecular geometry, twist-bend nematic phase and unconventional elasticity: a generalised Maier-Saupe theory.
Here, using a major extension of the Maier-Saupe molecular field theory, the transition from the nematic (N) to the NTB phase is described, and it is shown that on approaching the transition there is a gradual softening of the bend mode in the N phase.
A Liquid Crystalline Oligomer Exhibiting Nematic and Twist-Bend Nematic Mesophases.
  • R. Mandle, J. Goodby
  • Materials Science, Medicine
    Chemphyschem : a European journal of chemical physics and physical chemistry
  • 2016
This Communication presents a study on T49, a liquid-crystalline oligomer exhibiting the twist-bend nematic phase, which has a molecular length that is of comparable dimensions to the sub-10 nm pitch determined for CB9CB, and provides new insights into the differentiation between the nano- and macro-science for self-assembling supermolecular systems.
A molecular theory of nematic-nematic phase transitions in mesogenic dimers.
A simple molecular model that mimics the key features and symmetry (C2V) of this class of mesogens is presented and key experimental results on the NX phase of liquid crystalline dimers are discussed in the light of the theoretical predictions, which are also contrasted with the predictions of the twist-bend nematic model.
Nematic phase of achiral dimers spontaneously bends and twists
  • M. Čopič
  • Chemistry, Medicine
    Proceedings of the National Academy of Sciences
  • 2013
Chen et al. (1) report on experiments that confirm the existence of a fourth nematic phase with some very interesting properties, which form the basis for the ubiquitous use of modern liquid-crystal displays.
Molecular dynamics simulations of nematic phases formed by cyano-biphenyl dimers
ABSTRACT Molecular dynamics simulations of selected members of the cyano-biphenyl (CB) series of dimers (CBnCB) have been set up using atomistic detail for the description of the alkyl spacer and
The chirality of a twist-bend nematic phase identified by NMR spectroscopy.
The use of NMR spectroscopy is described to determine experimentally whether in reality the phase is chiral or not, and how the phase chirality can be demonstrated with probe molecules which contain deuteriated prochiral methylene groups.
Molecular shape as a means to control the incidence of the nanostructured twist bend phase.
A computational study of the conformational landscape reveals the octam methyleneoxy spacer to have a broader distribution of bend-angles than the nonamethylene equivalent, leading to reductions in the thermal stability of the TB phase.
Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase
ABSTRACT We produced controlled heliconical structures of a twist-bend nematic (NTB) liquid-crystal (LC) phase in nanoconfinement in a porous anodic aluminium oxide (AAO) film. The structural
Liquid crystals of the twenty-first century – nematic phase of bent-core molecules
Bent-core (BC) materials that form nematic liquid crystals (BC nematics (BCNs)) are known only since 2000, but since then they have been intensively studied. In this review we give a comprehensive