X-ray diffraction investigation of two mesomorphic copper(II) complexes of tetra-4-[(4-alkoxycarbonyl)phenyleneoxy]phthalocyanine

The mesomorphism and supramolecular structure of two homologues of copper tetra-4-[(4-alkoxycarbonyl)phenyleneoxyl]phthalocyanines are investigated using optical polarizing microscopy, differential scanning calorimetry (DSC), and X-ray diffraction. It is revealed that both homologues, which contain four and nine carbon atoms in aliphatic fragments of the lateral substituents, exhibit thermotropic columnar mesomorphism with a hexagonal arrangement of ordered columns (Col _ho). A change in the length of the aliphatic fragment has no noticeable effect on the mesophase type and leads only to variations in the parameters of the hexagonal lattice formed by the columns. The glass transition temperature of the homologue with n = 4 (T _g = 88°C) is considerably lower than that of the homologue with n = 9 (T _g = 88°C). It is established that the introduction of the cyclic fragment into the lateral substituent substantially affects the type of column packing as compared to the copper tetra-4-[(n-alkoxy)carbonyl]phthalocyanines studied in our earlier works. The assumption is made that this difference is associated, in particular, with the specific features of the penetration of the lateral substituents of the adjacent columns either in the presence or in the absence of the cyclic fragment in the lateral substituent.