Flying-seed-like liquid crystals 5: Liquid crystals based on octakisphenylthiophthalocyanine and their optical properties

Abstract

We have synthesized three novel flying-seed-like liquid crystals based on phthalocyaninato copper(II) (abbreviated as PcCu ) substituted by bulky groups {(o- C1) PhS (i), (m- C1) PhS (j), [m, p-( C1)2] PhS (k)} instead of using long alkyl chains, in order to investigate their mesomorphism. Their phase transition behavior and the mesophase structures have been established by using a polarizing optical microscope, a differential scanning calorimeter, and a temperature-dependent small angle X-ray diffractometer. As the results, [(o-C1)PhS]8PcCu (8i), [(m-C1)PhS]8PcCu (8j) and {[m,p-(C1)2]PhS}8PcCu (8k) show a Coltet.omesophase at 314.9~362.9 °C, a Colro(P2m) mesophase at 287.4~334.2°C and a Colro(P2m) mesophase at 331.8~386.8°C, respectively. Very interestingly, each of the derivatives thus exhibits a columnar mesophase at very high temperatures. The mesomorphism is apparently originated from the novel bulky groups (i~k). It is also noteworthy that the Q-bands of the present PhS-containing Pc derivatives 8i~8k in THF significantly red-shift by about 35 nm in comparison with those of the corresponding PhO-containing derivatives in THF.