Singlet oxygen quantum yields and photostability of planar binuclear phthalocyanines

The singlet oxygen (1O2) quantum yield of the near-infrared absorbing (λmax = 839 nm) planar π-conjugated binuclear zinc phthalocyanine (ZnPc) was measured and compared to the 1O2 quantum yields of the mononuclear and the planar binuclear phthalocyanine without π-conjugation between Pc rings. In addition, the photooxidative stability of the π-conjugated binuclear Pc was determined and compared to the stabilities of the mononuclear ZnPc and the known near-infrared photosensitizer, zinc tetra-tert-butylnaphthalocyanine (λmax = 761 nm). The results are explained by DFT calculations and cyclic voltammetry.