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N. E. Galanin¹, G. P. Shaposhnikov¹, A. I. Smirnova², А. V. Kazak², N. V. Usol'tseva²

Author affiliations
¹Research Institute of Macroheterocyclic compounds, Ivanovo State University of Chemistry and Technology,
Sheremetievsky Ave, 7, 153000 Ivanovo, Russia. 
E-mail: nik-galanin@yandex.ru
²Nanomaterials Research Institute, Ivanovo State University,
Ermak str., 39, 153025 Ivanovo, Russia. 
E-mail: antonia_smirnova@mail.ru

Abstract
New phthalocyanines with different quantity and ratio of donor and acceptor substituents in one molecule of the A₃B, ABAB and AABB types were synthesized by mixed-condensation of 3,6-dioctyloxyphthalonitrile (component A) and 4,5-dichlorophthalonitrile (component B). On the basis of the synthesized ligands the corresponding complexes with holmium (types A₃B-Ho, ABAB-Ho and AABB-Ho) were obtained. The spectral properties of the ligands and their holmium complexes in solutions were studied. A comparative analysis of the absorption and fluorescence spectra of new phthalocyanine derivatives with tetra-chloro-substituted analogues, which were obtained previously using 3,4,5,6-tetrachlorophthalonitrile, was performed. It was found out that the decrease in the number of acceptor substituents (chlorine atoms) in the phthalocyanine molecule results in a bathochromic shift of the maxima position of the Q band components for the ligands and their hypsochromic shift for holmium complexes. The mesomorphic properties of the synthesized phthalocyanines were studied by polarizing optical microscopy and differential scanning calorimetry. All the studied compounds as well as the corresponding analogues with 3,4,5,6-tetrahlorophthalonitrile fragments exhibit a thermotropic two-dimensionally ordered columnar mesophase; at temperatures of about 250 ^oC they are exposed to thermal decomposition, and therefore the transition to the isotropic phase cannot be reached. At low temperatures the compounds transform to glass state maintaining the texture of the mesophase.

Keywords: phthalocyanine, synthesis, mesomorphism, discotic mesogens, absorption spectra, fluorescence, holmium complexes