Structures and properties of dendrimers having peripheral 2,3-difluorobiphenyl mesogenic units: effects of dendrimer generation

1st-5th generation poly(propyleneimine) dendrimers having peripheral 2,3-difluorobiphenyl mesogenic groups have been synthesized. They exhibited smectic liquid crystalline behaviour. All the liquid crystalline dendrimers exhibited a smectic A (SmA) phase and a crystal E (E) phase. The SmA-isotropic phase transition temperature increased with increasing generation. In addition, a homeotropic structure was spontaneously formed on a glass plate in the SmA phase for the 2nd, 3rd, and 4th generation dendrimers. The hometropic structure remained unchanged in the phase.