Ground-state, fluorescence, triplet-state and singlet-oxygen luminescence studies are reported for two purpurins, a metallo (Sn^IV) purpurin and a porphyrin tautomer, NTW, containing an unsaturated meso-substituent. Fluorescence lifetimes of the purpurins are short (ca. 2 ns) and the fluorescence yields are low (<0.1). At room temperature, no fluorescence could be detected from NTW. Triplet quantum yields ϕ_T and singlet-oxygen quantum yields ϕ_Δ are high for the purpurins with ϕ_Δ/ϕ_T≈ 0.8 and triplet lifetimes in deoxygenated solvent are ca. 100 µs. The porphyrin NTW, however, has ϕ_T < 0.1 and a triplet lifetime of 18 µs. The dominant deactivation pathway (ϕ_1C > 0.9) for NTW is suggested to be free rotation/isomerisation of the unsaturated meso-substituent. These results are discussed with respect to the possible role of purpurins, the tautomeric porphyrin, NTW, and the photo-oxidation products as sensitisers for photodynamic therapy of cancer.