WAVELENGTH DEPENDENCE OF THE FLUORESCENCE AND SINGLET OXYGEN QUANTUM YIELDS OF NEW PHOTOSENSITIZERS

The photophysical properties of Mg and Zn tetrabenzoporphyrins and Cd- texaphyrin are presented. These sensitizers have strong absorption ban ds in the red and near-IR regions that make them good candidates for b iological photosensitization. Singlet oxygen quantum yields which were determined in an absolute manner, in several solvents, are reported. We show an unusual behavior regarding adherence to Kasha's and Vavilov 's rules: upon excitation to different electronic states, different va lues of singlet oxygen quantum yields were obtained. We also show an u nusual wavelength dependence of singlet oxygen and fluorescence yields upon excitation to different vibrational levels within the same elect ronic state.