<p>The nematic twist-bend (N<sub>TB</sub>)
liquid crystal phase possesses a local helical structure with a pitch length of
a few nanometres and is the first example of spontaneous symmetry breaking in a
fluid system. All known examples of the N<sub>TB</sub> phase occur in materials
whose constituent mesogenic units are aromatic hydrocarbons. It is not clear if
this is due to synthetic convenience or a <i>bona
fide</i> structural requirement for a material to exhibit this phase of matter.
In this work we demonstrate that materials consisting largely of saturated
hydrocarbons could also give rise to this mesophase. Furthermore, replacement
of 1,4-disubstituted benzene with <i>trans</i>
1,4-cyclohexane or even 1,4-cubane does not especially alter the transition
temperatures of the resulting material nor does it appear to impact upon the
heliconical tilt angle, suggesting the local structure of the phase is
unperturbed. Calculating the probability distribution of bend angles reveals
that the choice of isosteric group has little impact on the overall molecular
shape, demonstrating the shape-driven nature of the N<sub>TB</sub> phase. </p>
Landau theory for helical nematic phases