Synthesis, characterization and comparative studies on the photophysical and photochemical properties of peripherally and non-peripherally tetra-substituted zinc(II) phthalocyanines

In this study, the novel peripherally and non-peripherally tetra-substituted zinc(II) phthalocyanines were synthesized for the first time by cyclotetramerization reactions of corresponding four different phthalonitriles. All of these new zinc phthalocyanines were characterized by the spectral data (IR, 1H NMR, 13C NMR, UV–Vis and mass spectroscopies) as well as elemental analysis. These new zinc(II) phthalocyanines showed excellent solubility in many organic solvents. Surprisingly, the non-peripherally substituted zinc (II) phthalocyanine complexes (9 and 10) formed J-aggregates in non-coordinating solvents such as chloroform, dichloromethane and toluene. The formation of the J-aggregation was proved by UV–Vis and MALDI-TOF mass spectra of these complexes. The photophysical and photochemical properties of zinc phthalocyanine complexes were also investigated in DMSO. The investigation of the photophysical and photochemical properties of photosensitizers is very useful for photodynamic therapy (PDT) applications.