Asymmetrically tetra-substituted phthalocyanine derivatives: synthesis, photophysical and photochemical properties

The syntheses of highly soluble asymmetrically substituted metal free and zinc phthalocyanine derivatives bearing three 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) and one 4-(2-(benzo[d]thiazol-2-yl)phenoxy) groups or bearing one 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) and three 4-(2-(benzo[d]thiazol-2-yl)phenoxy) groups were reported for the first time in this study. The successful synthesis of phthalocyanines was achieved through the common statistical condensation method utilizing two different phthalonitriles named as 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy)phthalonitrile and 4-(2-(benzo[d]thiazol-2-yl)phenoxy)phthalonitrile. The asymmetrical phthalocyanines were characterized by spectroscopic methods. Moreover, the aggregation behavior, photophysical and photochemical properties of the substituted A3B type asymmetrical metal free and Zn (II) phthalocyanines were investigated in DMF. The asymmetrical Zn (II) phthalocyanine complexes produced highly singlet oxygen and appropriate fluorescence behavior in DMF suggesting that they can be suitable candidates as Type II photosensitizers in photodynamic therapy (PDT) applications.