Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions

Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.