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 [(CnH2n+1O)(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, [(C12H25O)(8)Pc] 2Ln, and a second series of bis(phthalocyaninato)erbium(III) double-deckers, [(CnH2n+1O)(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 [(C12H25O)(8)Pc](2)Er in contact with a substrate has also been investigated by scanning tunneling microscopy.