Zinc(II) phthalocyanines containing eight tert-butylphenoxy and tert-butylcarbazole groups at the molecule periphery (ZnPc(tBuPhO)8 and ZnPc(Carb)8, respectively) were obtained with about 20 % yield by the DBU activated phthalonitrile tetramerization in pentanol and dry quinoline, respectively. Their structure was confirmed using MALDI-TOF mass spectrometry, IR, 1H/13C NMR, and electronic absorption/fluorescence spectroscopy. The ZnPc(tBuPhO)8/ZnPc(Carb)8/H2Pc(tBuPhO)8 photophysical parameters, including the Q-band wavelength, fluorescence/singlet oxygen quantum yields, fluorescence lifetime, and radiative/non-radiative transition constant in organic solvents, were established. The presence of ZnPc(tBuPhO)8 and ZnPc(Carb)8 long-life excited states is confirmed by the fs-TA data. The peripheral carbazole substitution decreases slightly both the fluorescence quantum yield and fluorescence lifetime (by ∼0.6 ns) relative to that for ZnPc(tBuPhO)8, but simultaneously increases the possibility of singlet oxygen generation. The formation of the H2Pc(tBuPhO)8 proton transfer complex in dimethylformamide leading to the increase in singlet oxygen yield more than 3 times was established. Attractive photophysical parameters, non-aggregated state in solutions, and the bathochromically located Q absorption band allow us to consider ZnPc(Carb)8 as a promising photosensitizer.
