Peripheral and non-peripheral tetrasubstituted aluminium, gallium and indium phthalocyanines: Synthesis, photophysics and photochemistry

The synthesis, photophysical and photochemical properties of soluble triethyleneoxythia substituted aluminium, gallium and indium phthalocyanines (6a–c and 7a–c) are reported for the first time. The new compounds have been characterized by elemental analysis, FT-IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for quantum yields of photodegradation, fluorescence and fluorescence lifetimes as well as singlet oxygen quantum yields of these compounds. The effects of the position of the substituents and the nature of the metal ion on the photophysical and photochemical parameters of the Al(III), Ga(III) and In(III) phthalocyanines (6a–c and 7a–c) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for photodynamic therapy (PDT) applications. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.27 to 0.90. The substituted Al(III), Ga(III) and In(III) phthalocyanines showed high singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.