Tetra-2-[2-(dimethylamino)ethoxy]ethoxy substituted zinc phthalocyanines and their quaternized analoques: Synthesis, characterization, photophysical and photochemical properties

The new peripherally and non-peripherally tetra-2-[2-(dimethylamino)ethoxy]ethoxy substituted zinc (II) phthalocyanine complexes (2 and 4) and their quaternized amphiphilic derivatives (2a and 4a) have been synthesized and characterized for the first time. The quaternized complexes show excellent solubility in both organic and aqueous solutions, which makes them potential photosensitizer for use in photodynamic therapy (PDT) of cancer. Photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties of these novel phthalocyanines are investigated in dimethylsulfoxide (DMSO) for non-quaternized complexes and in DMSO, phosphate buffered solution (PBS) or PBS + triton X-100 (TX) for quaternized complexes. In this study, the effects of the aggregation of the molecules, quaternization and position (peripherally or non-peripherally) of the substituents and nature of the solvents (DMSO, PBS or PBS + triton X-100) on the photophysical and photochemical parameters of the zinc (II) phthalocyanines are also reported. A spectroscopic investigation of the binding of the quaternized cationic zinc (II) phthalocyanine complexes to bovine serum albumin (BSA) is also presented in this work.