Liquid-Crystalline Phthalocyanine Derivatives Bearing Oligosiloxane Moieties: Soft Columnar Mesophases Stabilized by Nanosegregation

摘要

Novel liquid-crystalline (LC) nickel phthalocyanine (Ni-Pc) complexes bearing eight oligosiloxane moieties such as disiloxane and trisiloxane were synthesized and their liquidcrystalline properties, as well as their carrier transport characteristics in the liquid-crystalline phase, were studied. These LC Ni-Pc complexes with eight oligosiloxane moieties exhibited a columnar mesophase over a wide range of temperatures, including room temperature. The bulky oligosiloxane moieties inhibited the aggregation of the Ni-Pc cores and stabilized the columnar structure by nanosegregation. Moreover, these LC Pc-Ni complexes showed homeotropic alignment in sandwichtype cells consisting of substrates coated with indium tin oxide. Time-of-flight measurements revealed ambipolar carrier transport properties in the columnar mesophases, in which electron transport was predominant.