Liquid-crystalline metallophthalocyanines containing late first-rowtransition metals

Abstract

Cobalt(II), nickel(II), copper(II) and zinc(II) phthalocyanines substituted by eight alkoxy chains in the peripheral (2,3,9,10,16,17,23,24) positions were prepared. The alkoxy chain lengths are octyloxy (C8H17O), dodecyloxy (C12H25O) and hexadecyloxy (C 16H33O). Studies by polarized optical microscopy and high-temperature X-ray diffraction revealed that all the complexes are liquid-crystalline and that they exhibit a hexagonal columnar mesophase (Colh). Transition enthalpies were determined by differential scanning calorimetry (DSC). The clearing point could only be observed for the compounds with the hexadecyloxy chains. The melting points depend on the central metal ion: NiII < CuII ≈ CoII < ZnII. The clearing point could only be observed for the compounds with the hexadecyloxy chains, and it was found that the nature of the metal ion has negligible influence on the clearing point.