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New Journal of Chemistry.... the home of new and emerging multidisciplinary work in the chemical sciences.
Paper
New J. Chem., 2005, 29, 378 - 384, DOI: 10.1039/b415314f
A comparison between the photophysical and photosensitising properties of tetraphenyl porphycenes and porphyrins
Noemí Rubio, Ferran Prat, Núria Bou, José I. Borrell, Jordi Teixidó, Ángeles Villanueva, Ángeles Juarranz, Magdalena Cañete, Juan C. Stockert and Santi Nonell
The photophysical properties of 2,7,12,17-tetraphenylporphycene (TPPo) and its palladium(II)(PdTPPo) and copper(II)(CuTPPo) complexes as well as comparisons with those of their porphyrin counterparts are reported. All porphycenes absorb in the red part of the spectrum, but only TPPo shows fluorescence (
F= 0.15). This compound presents good quantum yields of triplet (T= 0.33) and singlet oxygen (
= 0.23) formation. In the case of PdTPPo, fluorescence is inhibited by the internal heavy-atom effect and the triplet and singlet oxygen quantum yields are enhanced (T== 0.78). The presence of the paramagnetic ion Cu(II) in CuTPPo further enhances the non-radiative transitions leading to an internal conversion quantum yield ic= 0.65 and to a triplet quantum yield T= 0.35. With a triplet lifetime of 700 ns, CuTPPo is nevertheless able to sensitise singlet oxygen with a quantum yield that strongly depends on the oxygen concentration in the environment. These photophysical properties, together with their ability to kill several cancer cell lines, place these sensitisers in a good position to be used in photodynamic therapy (PDT).
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