Effects of pH on aggregation and photodynamic activities of cationic zinc phthalocyanines substituted with amides

This work reports on the effects of pH (especially base addition) on the properties of two cationic phthalocyanines substituted with amide groups. The absorption spectra, photo-stability, singlet oxygen generation ability and photodegradation of CT DNA of the two cationic phthalocyanines in different pH were studied and compared. Results indicated that the base additive can promote a shift in the amide/imidohydrine balance toward imidohydrine, which resulted in the reduction of aggregate and enhancement of photodynamic activities. This base induced tautomeric transformation could be a novel way to generate low aggregated and high photodynamic efficiency cationic Pcs.