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

A homologous series of new thioalkylated double-decker cerium phthalocyanine complexes, [(CnH2n+1S)(8)Pc](2)Ce, 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 Colh mesophase of the longer chain homologue was successfully measured by a TOF technique as having a value of 7 x 10(-3) cm(2) V-1 s(-1).