A novel chlorin derivative of meso-tris(pentafluorophenyl)-4-pyridylporphyrin:: Synthesis, photophysics and photochemical properties

Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer. such as a porphyrin or a chlorin, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorin-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorin derivatives 4. (5,10.20-tris(pentafluorophenyl)-15-(4-pyridyl)tetrahydro-1H-N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4pyridyl)-tetrahydro-1H-N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis.H-1 NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorin 4 have been evaluated. Its quantum yield of photobleaching (phi(Pb), mol Einstein(-1)) was 0.047+/-0.014. In order to demonstrate the production of O-1(2) when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorin 4 can be considered a promising photosensitizer in PDT.