Structural variants of RM734 in the design of splay nematic materials

The recent discovery of the splay nematic phase, a new nematic polymorph that has been found to be both polar and ferroelectric, is the lead paragraph in an entirely new chapter in the history of liquid crystals. The potential for transformative applications utilising this state of matter–such as photonics, non-linear optics, memory applications and so on–can only be met with significant improvements in the temperature range of existing materials such as 4-(4-nitrophenoxycarbonyl)phenyl 4-methoxy-2-methoxybenzoate (RM734). Herein we present several families of materials which are structurally related to the archetypal new nematic material, RM734, including the first non-rod-like materials within the context of the splay nematic phase. We find that the incidence (or absence) of this new nematic variant in a designer material cannot be easily rationalised in terms of molecular dipole moment or polarisability. However, mixture formulation shows promise for the engineering of materials with improved working temperature ranges.