Synthesis of novel push-pull unsymmetrically substituted alkynyl phthalocyanines

Two families of "push-pull" phthalocyanines 1-3 having an unusually strong dipole moment have been prepared. The syntheses of unsymmetrically substituted phthalocyanines 1a,b and 2 bearing one or two electron-withdrawing 4-nitrophenylethynyl moieties, respectively, and six alkoxy substituents were performed by combination of a zinc or nickel templated cyclotetramerization and cross-coupling palladium mediated methodologies. In a similar way, the "push-pull" compounds 3a,b having a reversal substitution pattern, characterized by the presence of one electron-donor 4-(dimethylamino)phenylethynyl unit and six strong acceptor alkylsulfonyl substituents were prepared. The compounds show very large second-order nonlinear optical responses.