Preparations and photosensitizing properties of 2,7,12,17-tetran-n- propylporphycenatotin(IV) dihalide complexes

2,7,12,17-Tetra-n-propylporphycenatodihalotin(IV) complexes ([Sn(TPrPc)X₂], X = F, Cl, and Br) were synthesized and their photophysical properties were investigated. These complexes exhibit strong absorptions in the red region (600630 nm). Strong quenching was observed during the fluorescence emission of the dibromotin(IV) complex, which is caused by an intramolecular heavy-atom effect. The complexes emit NIR phosphorescence in 1-iodopropane at room temperature and the intensity of the emission of the dibromotin(IV) complex is found to be smaller than that of the dichlorotin(IV) complex. The quantum efficiency (φ_δ) of generation of singlet oxygen using the dibromotin(IV) complex is the highest among the porphycenatotin(IV) complexes (φ_δ = 0.79). Photooxidation of 1,3-diphenylisobenzofuran catalyzed by the complexes upon irradiation with red light (over 600 nm) was studied and a rapid oxidation of the substrate was observed when using the dibromotin(IV) complex.