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In this article we report on the characterization and properties of several unsymmetrical phenyl-benzoate bimesogens that exhibit the soft-matter, twist-bend nematic (NTB) phase. We use this study as a basis to examine the phase behaviour of associated novel trimeric and tetrameric materials, in order to investigate the potential for oligomeric materials to form the NTB phase. Based on our results we hypothesise that higher oligomers and even polymers are highly likely to exhibit the NTB phase, provided they retain a gross bent structure between consecutive mesogenic units. Thus we show at the level of nanoscale organization, dimers can template with respect to one another to form mesophases that are also found in macromolecular systems.

In the current fascination with liquid crystalline dimers, bimesogens and oligomers the role of the central spacer in these systems has perhaps been somewhat neglected. In compound 1, a phenyl 4-cyanobenzoate bimesogen, the central spacer incorporates a methyl group at the 2-position and is therefore chiral. The helical twisting power of 1, measured in both 5CB and E7, was found to be 0.36 and 0.35 μm

A large selection of photochromic dihydroazulene (DHA) molecules incorporating various substituents at position 2 of the DHA core was prepared and investigated for their ability to form liquid crystalline phases. Incorporation of an octyloxy-substituted biphenyl substituent resulted in nematic phase behavior and it was possible to convert one such compound partly into its vinylheptafulvene (VHF) isomer upon irradiation with light when in the liquid crystalline phase. This conversion resulted in an increase in the molecular alignment of the phase. In time, the meta-stable VHF returns to the DHA where the alignment is maintained. The systematic structural variation has revealed that a biaryl spacer between the DHA and the alkyl chain is needed for liquid crystallinity and that the one aromatic ring in the spacer cannot be substituted by a triazole. This work presents an important step towards employing the dihydroazulene-vinylheptafulvene photo/thermoswitch in photoactive liquid crystalline materials.