Syntheses and photophysics of new phthalocyanine derivatives of zinc, cadmium and mercury

Abstract

The syntheses of novel tetra{2,(3)-pyridyloxyphthalocyaninato} complexes of zinc, cadmium and mercury (TPyZnPc, TPyCdPc and TPyHgPc) are presented. Their spectral and photophysical properties (as well as those of their unsubstituted counterparts: ZnPc, CdPc and HgPc) are investigated. TPyZnPc and TPyCdPc are aggregated in non-coordinating solvents such as chloroform, while TPyHgPc is demetallated, as evident from their respective absorption spectra. The trends in fluorescence (Φ_F), triplet (Φ_T) and singlet oxygen (Φ_Δ) quantum yields are explained in terms of relative strengths of spin–orbit coupling induced by the respective central metal ions in the complexes. The effect of the pyridyloxy substituents is a decrease in Φ_F and an increase in Φ_T values. The complexes are less fluorescent in DMSO but possess higher Φ_T, triplet lifetimes (τ_T) and Φ_Δ therein.