Synthesis, photophysics, and photochemistry of ball-type phthalocyanines

Abstract

Phthalocyanines (Pcs) have numerous potential applications, including use as photosensitizers for photodynamic cancer therapy. These applications depend on specific photodynamic properties; therefore, new Pc compounds with unique and well characterized properties are in constant demand. In this study, four novel ball-type Pc compounds were synthesized with 1,2-benzenediol as a substituent, including one non-metal complex (H4Pc2) and three metal-containing complexes (Mg2Pc2, Co2Pc2, and Zn2Pc2). The structures of the synthesized compounds were characterized using common spectroscopic methods. Quantum yields for fluorescence (ΦF), triplet state (ΦT), singlet oxygen (ΦΔ), and photodegradation (Φd) were measured except Co2Pc2 in dimethylsulfoxide. All the three compounds exhibited low fluorescence quantum yield, high triplet quantum yield, and good stability in organic solvent, suggesting acceptable photostability. Complexes with H4Pc2 and Mg2Pc2 demonstrated differences in the Q band in their Uv–Vis spectra. Singlet oxygen quantum yield was 0.35 for Zn2Pc2. Fluorescence lifetimes (τF) for the complexes ranged from 6.67 to 2.95 ns, while triplet state lifetimes (τT) ranged from 50 to 440 μs. This novel group of Pcs possesses properties suitable for photodynamic therapy, particularly ZnPc.