Abstract:
SnIJIV) porphyrins ([SnIJIV)TTPIJ3PyO)2] (5) and [SnIJIV)TPPIJ3PyO)2] (6) [tetrathienylporphyrin (TTP), tetraphenylporphyrin
(TPP), and pyridyloxy (PyO)]) were prepared and characterized and their photocytotoxicity
upon irradiation with 625 nm light has been studied. The presence of the 3PyO axial ligands was found to
limit the aggregation and enhance the solubility of 5 and 6 in DMF/H2O (1 : 1). The photophysical properties
and photodynamic therapy (PDT) activity of the meso-2-thienyl and meso-phenyl-substituted SnIJIV) porphyrins
are compared. 5 and 6 were found to be photocytotoxic in MCF-7 cancer cells when irradiated
with a Thorlabs M625L3 LED at 625 nm but remained nontoxic in the dark. The PDT activity of SnIJIV)
meso-tetra-2-thienylporphyrin 5 was found to be significantly enhanced relative to its analogous tetraphenylporphyrin
6. There is a marked red-shift of the Q00 band of 5 into the therapeutic window due to
the meso-2-thienyl rings, and 5 has an unusually high singlet oxygen quantum yield value of 0.83 in DMF.
The results demonstrate that readily synthesized axially ligated SnIJIV) meso-arylporphyrins are potentially
suitable for use as singlet oxygen photosensitizers in biomedical applications and merit further in depth investigation
in this context.