Synthesis of all-cis and all-trans tetrakis(phenylvinylene)-phthalocyanines

We have synthesized a series of tetrakis(arylvinylene)phthalocyanines from the corresponding phthalonitriles. Substitution of the para-fluorine in the pentafluorphenyl ring with an alkoxy group from the solvent occurs during the synthesis. This substitution can be suppressed by the addition of zinc chloride or tin chloride to the reaction mixture. According to 1 H and 19 F NMR data, the cis- or trans-conformations of the starting materials are retained during condensation; thus the phthalocyanines formed are in all-cis or all-trans form. Cis-trans photoisomerization occurs easily for phthalonitriles, while phthalocyanines retain their conformations under UV beam.