No. R = Melt NF-N/Iso N-Iso All the halogen terminated homologues exhibit monotropic nematic phases with only the iodine terminated derivative exhibiting the NF phase (Fig. ). The values of TN-I remain almost constant for the three largest halogens, with a significant decrease observed for the fluorine terminated derivative. We optimised the geometries of RM734 and compounds 6 -9 at the B3LYP/LAN2LDZ level of DFT in order to rationalise the trends in observed mesophase behaviour (Table ). Immediately it is clear that a halogen atom at the 4-position leads to the expected reduction in molecular electric dipole moment relative to the parent RM734. The shape anisotropy parameter is almost constant across this series, while the rotational anisotropy parameter follows the expected trend as a consequence of the large mass of the halogen atom.