A nematic Schlieren texture containing both 2-and 4-point brush defects observed for compound 4 (a), an example of the banded texture of the NF phase observed for compound 3 (b), and the growth of point singularities at the isotropic-NF phase transition observed on cooling for compound 2 (c). All textures were observed between untreated glass slides. Transition temperatures (T, °C) and associated enthalpies (ΔH, kJ mol -1 ) for compounds 1-5.