Synthesis, spectral and mesomorphic properties of octa-alkoxy substituted phthalocyanine ligands and lanthanide complexes

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 CH3O to C20H41O. Trivalent lanthanide ions form with phthalocyanine ligand complexes of the type Pc2Ln, where the lanthanide ion is sandwiched between two phthalocyanine rings. Hitherto, most of the mesomorphic Pc2Ln complexes described in literature have Lu(III) as the central metal ion. We prepared lanthanide 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 differential scanning calorimetry (DSC). The metallomesogens exhibit a columnar mesophase. Solution absorption and MCD spectra were also investigated.