A new procedure for the synthesis of water-soluble tri-cationic and -anionic phthalocyanines

A series of water-soluble tri-anionic and -cationic substituted phthalocyanines has been synthesized via iodinated boron subphthalocyanines. The latter were opened with differently substituted diiminoisoindolines via the Kobayashi ring expansion reaction followed by metal insertion to exclusively yield the asymmetrically 3:1 substituted iodinated zinc phthalocyanines. These iodinated phthalocyanines readily underwent palladium-catalyzed coupling reactions with terminal alkynes such as 5-hexynoic acid and 10-undecynoic acid to give anionic phthalocyanines, or with 2-ethynylpyridine and 3-ethynylpyridine followed by N -methylation to give cationic phthalocyanines. These novel asymmetrically substituted charged phthalocyanines could have interesting properties as photosensitizers for photodynamic therapy.