Synthesis and in vitro photodynamic activity of mono-substituted amphiphilic zinc(II) phthalocyanines

A series of novel zinc(II) phthalocyanines mono-substituted with a 1,3-bis(dimethylamino)-2-propoxy group at the α- or β-position, and the corresponding di-N-methylated derivatives, have been synthesized. All these compounds can generate singlet oxygen effectively and exhibit high in vitro photodynamic activities toward HT29 human colorectal carcinoma cells with IC50 values down to 0.08 μM. The dicationic derivatives have a higher affinity to the cell membrane compared with the non-ionic counterparts.