Synthesis and characterisation of an unsymmetrical, ether-linked, fluorinated bimesogen exhibiting a new polymorphism containing the NTB or ‘twist-bend’ phase

Abstract

In this article we report on the liquid crystal phases and properties of the bimesogen 4-((11-((4′-fluoro-[1,1′-biphenyl]-4-yl)oxy)undecyl)oxy)-2,3-difluoro-4′-(4-propylcyclohexyl)-1,1′-biphenyl. This material was shown to exhibit an Iso Liq–N–N_TB–SmA phase sequence, thereby clearly indicating that the N_TB phase possesses an ordering of the constituent molecules that is between that of a conventional nematic and the smectic A phase. This compound allows us to better understand the relationship between molecular structure and the N_TB phase, and we conclude it is the gross topology that dictates the incidence of this fascinating phase and not molecular properties such as dipole moment and bend angle.