Photophysical properties of 5,10,15,20-tetrakis(m-hydroxyphenyl)porphyrin-(m-THPP), 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (m-THPC) and 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (m-THPBC): a comparative study

For the tumour photosensitisers m-THPP, m-THPC,and m-THPBC in methanol the following photophysical properties have been measured. absorption and fluor escence spectra, E-s, Stokes shift, Phi(f), Phi(T), tau(T), dioxygen quench ing rates, and Phi(Delta) for air-saturated and oxygen-saturated solutions. The properties of the first excited triplet-state are quite uniform across this series. The quantum yields of singlet oxygen formation are high, bein g 0.43-0.46 in air-saturated methanol, and 0.59-0.62 in oxygen-saturated me thanol; For a constant substitution pattern and a standard given light dose , tumour photonecrosis in vivo appears to parallel the product of drug dose and the molar extinction at the irradiation wavelength in the red region o f the visible spectrum.