title: Photosensitizers for photodynamic therapy: One-pot heterogeneous catalytic transfer reduction of porphyrins.
abstract: A number of new porphyrin-based photosensitizers have been developed for Photodynamic Therapy (PDT) in recent years. Chlorins, which are a reduced form of porphyrins, show better potential of application since they have a stronger absorption band on the red region of the visible spectrum and, hence, a deeper penetration into tissues. We found that by using heterogeneous catalytic transfer reduction (CTR), meso-tetraphenylporphyrin (TPP) could be hydrogenated, although in modest yields, to meso-tetraphenylchlorin (TPC) in a single reaction step. Best reaction conditions were attained using formic acid or sodium phosphinate/water as hydrogen donors, tetrahydrofuran (THF) or toluene as solvent and 10% palladium on charcoal as catalyst.
authors.affiliation: CIQA and DQF, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors.forename: Amadeu F
authors.initials: AF
authors.lastname: Brigas
authors.forename: Ana M
authors.initials: AM
authors.lastname: Rosa da Costa
authors.forename: Arménio C
authors.initials: AC
authors.lastname: Serra
authors.forename: Catarina
authors.initials: C
authors.lastname: Pires