Group IIA alkaline-earth metal phthalocyanines: Synthesis, photoluminescence and singlet oxygen formation

Abstract

We have synthesized Group IIA alkaline-earth metal phthalocyanine (PC) complexes (BePC, MgPC, CaPC, SrPC, BaPC) using four different methods to study their photoluminescence and singlet oxygen photosensitizing properties. Their UV–Vis electronic absorption, fluorescence emission and excitation spectra, fluorescence quantum yields and lifetimes, as well as singlet oxygen formation quantum yields have been measured. The results reveal that alkali-earth metal PCs (BePC, MgPC, CaPC, SrPC, and BaPC) have high fluorescence quantum yields (0.50 to 0.70) and long fluorescence lifetimes (7.1 to 7.9 ns). SrPC, and BaPC also show high quantum yield of singlet oxygen formation (0.40 to 0.50). Therefore, alkaline-earth metal phthalocyanines are appealing fluorescent sensors and singlet oxygen photosensitizers for photodynamic therapy of tumors.