POTENTIAL PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY .3. PHOTOPHYSICAL PROPERTIES OF A LIPOPHILIC CHLORIN AND ITS ZINC AND TIN CHELATES

Photophysical properties of a lipophilic chlorin derivative and its zinc and tin chelates were investigated in chloroform. The quantum yields of the fluorescence phi-F, of the S1 --> T1 intersystem crossing phi-T and of singlet oxygen (1-DELTA-g) formation phi-delta, as well as the Stern-Volmer constants for the quenching of the S1 states by oxygen and the rate constants of quenching of O2(1-DELTA-g) by the chlorins were measured. In comparison to the metal-free chlorin an increase of phi-T and a decrease of phi-F have been observed for the metal-containing derivatives, whereas the phi-delta values remain constant.