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 2n+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) doubledeckers , [(C n H 2n+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.

By functionalizing the phthalocyanine Pc ring with long aliphatic chains, liquid-crystalline compounds can be obtained. In order to investigate the influence of chain length on mesophase behaviour, we prepared a series of homologous peripherally octa-alkoxy substituted phthalocyanines. The alkoxy chain length was varied from CH O to C H O. Trivalent lanthanide ions form with 3 2 0 4 1 phthalocyanine ligand complexes of the type Pc Ln, where the lanthanide ion is sandwiched between two phthalocyanine rings. Hitherto, 2 Ž. most of the mesomorphic Pc Ln complexes described in literature have Lu III as the central metal ion. We prepared lanthanide 2 complexes of peripheral octa-alkoxy substituted phthalocyanines in order to investigate the influence of lanthanide ion on thermal behaviour. The thermal properties of ligands and complexes were investigated by hot-stage polarising optical microscopy and by Ž. differential scanning calorimetry DSC. The metallomesogens exhibit a columnar mesophase. Solution absorption and MCD spectra were also investigated.

Lanthanide bisphthalocyanine complexes are interesting objects for the construction of two-dimensional (2D) ordered arrays with prospective applications in molecular electronics due to their unique semiconductor and electrochromic properties as well as their double-decker architecture. The 2D self-assembly of dodecyloxy-substituted (bisphthalocyaninato)erbium(III) has been studied at the solid (highly oriented pyrolytic graphite)-liquid interface by scanning tunneling microscopy. The results show that the bisphthalocyanine molecules form an ordered quadratic 2D lattice (a = b = 3.0 +/- 0.1 nm, gamma = 90 +/- 3 degrees), which is nearly identical to that formed by its (phthalocyaninato)cobalt(II) analogue bearing alkoxy chains of the same length. This clearly shows that sandwich molecules adsorb to the graphite surface by one of the phthalocyanine disks and its eight alkoxy groups. Despite the very similar mode of interaction with the surface, mixtures of alkoxylated (bisphthalocyaninato)erbium(III) with its (phthalocyaninato)cobalt(II) analogue show partial phase separation on the nanoscale: areas are enriched in one of the compounds. A much clearer phase separation between (bisphthalocyaninato)erbium(III) and (phthalocyaninato)cobalt(II) molecules was achieved by mixing molecules containing alkoxy groups of different length. The results provide insight for the development of well-ordered nanostructures of bisphthalocyanines in the presence of phthalocyanines, which could be of importance for future nanometer-scale functional materials.