Unsymmetrical phthalocyanines with alkynyl substituents

We report on the synthesis and characterisation of unsymmetrical metallophthalocyanines (M = Zn, Ni, Co) which carry two peripheral hexylthio substituents on each of three of the benzenoid groups, while the fourth one carries two phenylethynyl groups. The synthesis of unsymmetrically substituted metallophthalocyanines (M = Zn, Ni, Co) bearing two phenylethyl moieties and six alkythio substituents was achieved by co-cyclotetramerization of two different phthalonitrile derivatives, namely 4,5-di(hexylthio)phthalonitrile and 4,5-di(phenylethynyl)phthalonitrile in the presence of zinc, cobalt or nickel salts. In contrast to the totally alkyne substituted phthalocyanines, these partially alkyne-containing derivatives are more soluble and their Q band absorptions are red-shifted when compared with all alkylthio phthalocyanines. Electrochemical properties of the phthalocyanines were studied by cyclic voltammetry.