Structure and Mesomorphic Behavior of Alkoxy-Substituted Bis(phthalocyaninato)lanthanide(III) Complexes

The influence of the lanthanide ion and the chain length on the thermal properties of bis[2,3,9,10,16,17,23,24-octakis(alkoxy)phthalocyaninato]lanthanide(III) complexes, denoted in the following as [(C n H 2 n +1 O) 8 Pc] 2 Ln, have been investigated. Two series of complexes were considered: a first series in which the alkoxy chain was kept constant with different lanthanide ions (Ln = Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), namely, [(C 12 H 25 O) 8 Pc] 2 Ln, and a second series of bis(phthalocyaninato)erbium(III) double-deckers, [(C n H 2 n +1 O) 8 Pc] 2 Er, with different alkoxy chain lengths ( n = 4−18). All these metallomesogens exhibit a hexagonal columnar mesophase (Col h ) over wide temperature ranges. It was found that the transition temperatures were not affected to a great extent by the lanthanide ion and that they could be tuned by a proper choice of the alkoxy chain length. The orientational behavior of [(C 12 H 25 O) 8 Pc] 2 Er in contact with a substrate has also been investigated by scanning tunneling microscopy.