Photophysical studies of some 5,10,15,20-tetraarylethynylporphyrinatozinc(II) complexes as potential lead compounds for photodynamic therapy

The photophysics of 5,10,15,20-tetraarylethynylporphyrinatozinc(II) complexes, 1 and 2, are reported, Compared to 5,10,15,20-tetraphenylporphyrinatozinc(II) (ZnTPP), the UV/visible spectra of 1 and 2 have red-shifted B and Q bands, with the Q bands of increased intensity relative to the B band. Fluorescence quantum yields and lifetimes and triplet quantum yields and lifetimes are similar to ZnTPP. However, quantum yields for in vitro singlet-oxygen generation are much larger than for ZnTPP and for 2 the quantum yield is near unity, These findings suggest that the title compounds could be potential lead compounds as sensitizers for photodynamic therapy.