Controlling the reactivity of phthalonitriles for the efficient synthesis of chiral phthalocyanines with self-assembly abilities

Binaphthol-bridged phthalonitriles are common precursors for the preparation of chiral phthalocyanines (Pcs). However, self-condensation of these phthalonitriles usually leads to the target Pcs in extremely low yields. In this work, we report a smart approach to enhance the reactivity towards self-condensation of binaphthol-bridged phthalonitriles, which relies on the addition of another highly reactive phthalonitrile that initiates the macrocyclization process, but it is eventually released. After optimization of the reaction conditions, ethynyl-containing binaphthyloxy-bridged Zn(ii)Pc (AA)2-2 has been obtained in remarkable yields. This Pc synthon has been further endowed with hydrophilic cationic tails, giving the strongly amphiphilic Zn(ii)Pc 1, which has shown the ability to form nanostructures in aqueous solutions. 4-Nitrophthalonitrile was used to initiate the self-condensation of binaphthyloxy-bridged phthalonitrile AA-2, rendering the elusive Zn(ii) phthalocyanine (AA)2-2 that was further endowed with cationic tails to form an amphiphilic derivative.

Automated summary

In this work, a smart approach to enhance the reactivity towards self-condensation of binaphthol-bridged phthalonitriles was reported, which relies on the addition of another highly reactive phthalonitrile. By optimizing the reaction conditions, a high-yield ethynyl-containing binaphthyloxy-bridged Zn(ii)Pc was obtained, which has the ability to form nanostructures in aqueous solutions.