Liquid crystalline and charge transport properties of double-decker cerium phthalocyanine complexes

Abstract

A homologous series of new thioalkylated double-decker cerium phthalocyanine complexes, [(C_nH_2n+1S)₈Pc]₂Ce, were synthesised and their mesomorphisms were clarified by DSC, polarized optical microscopy and X-ray diffraction. Unlike other lanthanide phthalocyanines, these double-decker cerium compounds were found by spectroscopy and X-ray crystallography to be neutral complexes. A hexagonal columnar mesophase (Col_h) was exhibited by all homologues prior to melting to the isotropic liquid. Interestingly, the columnar mesophases of these compounds showed strong tendencies for spontaneous homeotropic alignment on non-treated glass substrates or ITO coated glass. The hole mobility in the Col_h mesophase of the longer chain homologue was successfully measured by a TOF technique as having a value of 7 × 10⁻³ cm² V⁻¹ s⁻¹.